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Astro Nerds Astronomy magazine is a free to read and download ezine. In this months editions we have our image gallery dedicated to Comet Lovejoy. Methane on Mars and anothe rlook at the sun plus much much more....ENJOY
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ICY SCIENCE PUBLICATION: WWW.ICYSCIENCE.COM: WINTER 2013/14
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SPECIAL TAHNK YOU TO
Thomas J. Nelson
Roy Alexander
John Harper F.R.A.S
Joolz Wright
Andrew Devey
Nicole Willett
Alaistair Leith
Liam Edwards
If you are interested in
featuring or advertis-
ing in Astro Nerds Ezine,
Icy Science E-Magazine
contact
Twitter: @
DavesAstronomy
www.icyscince.com
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WelcomeFebruary 2015 is already upon us. Because
of Christmas and New Year there was no
January edition of Astro Nerds, however this
month we have a packed edition for you.
Comet Lovejoy dominated the social media
forums, so this month we have dedicated
our image galaxy to the famous comet. We
have a two part series on Astrophotography
without a telescope, the series looks at the
pros and cons and difficulties that the astro
photographer will face. A new observatory
is opening up called Battlesteads observa-
tory and Joolz Wright tells us about the new
astronomy group Matlock and Darley Dale
observing group. We also have our monthly
slots looking at the Sun with Andrew Devey,
Mars for Nicole Willett and a guide to the
night sky by John Harper FRAS.
Front Cover Image by David Dvali,
from Tbilisi, Georgia, The Rosetta
Nebula
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In This Edition
6. The Astro Maddogs Are Unleashed
12. Comet C/2014 Q2 LOVE JOY
22. AR2192 returned as AR2209 in the second half of November 2014
30. The Curious Case for Methane on Mars, methane and active organics discovered on Mars
38. Battlesteads Observatory
50. Comets What Are They?
54. Astro News
56. Astrophotography Without a Telescope
76. Look Up- The Night Sky
80. Caldwell 23
82. Black Holes
86. M42 Great Orion Nebula
88. Aether Project
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Shot of the moon taken by David Bood Using a Nikon D3200 camera mounted on a sky watcher 130
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The Astro MaDDOGs are
UnleashedAstronomy can be a lonely business. Unless you want to drive to
an astronomy event, or your local Astronomy Society the alterna-
tive is to seek out a beautiful dark spot and set up your scope alone
in the middle of nowhere jumping at every rustle, snuffle and twig
snapping. Many back garden astronomers fight street and security
lighting...the curse of many usually placid souls- reduced to forceful
letter writing, angry words or sadly defeat ( when the catapult has
been finally been confiscated by the exasperated other half! ) If, like
me, you are lucky enough to have dark skies from your back garden
it can still be a lonely and daunting business. Even when I know the
cows are in the field above the house I am totally freaked out when
they decide to midnight snack on the tempting weeds and over-
grown grass in between their field and my garden. Have you ever
heard the noise a cow makes pushing its head through a wire fence
, chomping and snorting as it goes? It’s bloody terrifying, I can tell
you! They chew like a thug in hobnail boots stomping across gravel!
Anyway, it was this kind of scenario that led me to think there must
be other frustrated astronomers nearby who would like the social
aspect of our wonderful hobby. For those who have been to star
camps or local society observing nights you will understand the joy
of sharing the night sky with likeminded others. The other aspect,
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a vibrant astro community on social network, sharing our
passion, frustrations and triumphs via Twitter and Facebook
Groups. I already had all of this but with a fabulous bunch of
people who were miles away.
I regularly spoke with a friend in the village who was also a
keen amateur astronomer and when we met up with another
local astronomer at the North West Astronomy Festival, we
all agreed there was room for an informal, astronomical gath-
ering on our doorstep.
A few messages, a dilemma for a name and a hunt for a local
“home” later the MaDDOGs were born! The Matlock and
Darley Dale Observing Group , to give it our Sunday name, was
launched in November via Social Media with huge support
from the on line astro community. Messages of encourage-
ment and lots of help and guidance behind the scenes from
astronomy friends had us up and running in no time!
We were also supported by our local community facility at
the Whitworth Centre who offered us a room there free of
charge for our first meeting.
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Nigel-The Cosmic Whirlwind!
We were very privileged to have renowned astronomer/
speaker and Aurora flight guide Nigel Bradbury on our
doorstep too, who didn’t hesitate to offer launching our
first gathering with a vibrant Sky Tour and Aurora talk! He
also very generously funded the equipment hire.
So the MaDDOGs were unleashed in December, and with
flyers, social networking and word of mouth our first
meeting was a healthy group of enthusiastic astronomers
of all abilities, ages and experience...just as we had hoped
for! . ..and we had cake!! To keep some kind of continu-
ity we decided to plan to meet on the first Monday of
each month, with either observing, weather permitting,
or a social gathering to swap news and plans. Like all great
astronomy gatherings at some point the local pub would
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be involved and we were no exception when our next planned meet was thwarted by clouds. This event
saw even more members and included a visit from a member of neighbouring White Peak Astro with lots
of friendly help and advice.
Not the darkest site but a great atmosphere!
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We decided to meet for an observing session when the
forecast looked good...and the excitement of hunting for
Comet Lovejoy was too good to miss. With word soon
spread via the usual channels a group of us met the fol-
lowing night in the park, where we aim to regularly meet.
Unfortunately due to other events at the nearby Whitworth
Centre building the floodlights didn’t help with our viewing,
the disadvantage of meeting earlier in the winter months,
also the lack of leaves on the trees meant the streetlights
were not screened so much, but the atmosphere was won-
derful !We even managed to spot a comet through hazy ,
increasingly building cloud! (not the best image you’ll see
but we managed under adverse conditions!)
All of this plus a very bright Moon! The good thing was the
Moon gave us a target to help some of the less experienced
members of the group a shot at observing and photogra-
phy....and he looked magnificent! It wasn’t long before the
cloud set in for the night so we didn’t really get to experi-
ence the sky together as long as we had hoped...but our
fingers and toes went numb whilst we stood chatting and
discussing our astro stories in the cold dark park!
So that’s where we are to date. We have had numerous
offers of talks and workshops from astronomers from other
societies, enough to take us through the shorter summer
nights and our members are growing as word spreads
rapidly. I’ve even been interviewed by the local press, when
The fuzzy green blob aka Comet Lovejoy
Below: Almost a full moon
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all I asked for was an announcement in the “what’s on”
column! We ended up with a rather large four column
entry! All good for spreading the MaDDOGs’ word! Our
plans for the MaDDOGs are that we remain a vibrant,
social and most importantly FREE astronomy group. We
don’t have a committee , just three admins ( affectionately
dogsbodies ! ) and we aim to just share our passion of the
night skies as and when time and conditions allow. So if
you want to join us have a look at our various sites listed
below...all welcome, and although I can’t promise observ-
ing by a field of chomping cows may not be involved at
some point, at least we will be in a pack ;-)
Clear Skies!
ARTICCLE: JOOLZ WRIGHT
Please click on a link below to visit
www.maddog.org.uk
www.facebook.com/groups/themaddogs
www.twitter.com/ASTROMADDOG
www.flickr.com/groups/astromaddogs
The Matlock Mercury
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12 COMET C/2014 Q2 LOVEJOY
Comet Lovejoy from tonight using a Canon
1100D & 5” Refractor
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COMET C/2014 Q2 LOVEJOY
C/2014 Q2 (Lovejoy) is a long-period comet discovered on 17 August 2014 by Terry Lovejoy using a 0.2-meter Schmidt–Cassegrain telescope. It was discovered at apparent magnitude 15 in the southern constellation of Puppis
Alastair Leith (OAS) 60 sec exp ISO 400taken Jan 10th 2015
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Image; Nick Howes
Final stack of today’s (16/1/15) imaging run on C/2014
Q2. Luminance and R band, with a synthesised green
channel using Noels actions. TOA150 /6303 CCD at
Tzec Muan/SSO
10 x 120s/channel
Combined Maxim DL 6.08
Colour combined and starfield layered with median
stack comet image in Photoshop CS5
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Andrew Daves taken from Wigg island 700mm Refractor, Canon 600D, 5 x 30 second exposures.
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COMET LOVEJOY (BOTH IMAGES) BY James Parker@JP_Astronomy (TWITTER)
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COMET LOVEJOY (BOTH IMAGES) BY James Parker@JP_Astronomy (TWITTER)
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Wendy Clark
Comet Lovejoy 16 Jan 2015
After another 24 hr battle I’ve come to like this
despite not being totally happy at first. Taken with
a Skywatcher 120ED on AVX & Canon 700D, 0.85
coma corrector/reducer.
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22 AR2192 returned as AR2209 in the second half of November 2014
The huge active region NOAA12192 or AR2192 the largest AR for 24 years returned as NOAA12209 or AR2209
on the 14th November 2014 and released a further three M-class flares [M3.2 and M3.7 on 15 November and
M5.7 on the 16 November 2014] and a further 31 C-class flares with the last one on the 23 November. Every
time an active region releases a flare its energy is diminished. Sadly the day this region returned coincided with
the death of my father and so my observation and imaging activities were severely curtailed during this period
as I returned to the UK. Here is a list of the solar flares released by 12209. The times are Universal Times, the
table shows the start time, peak event time, finish time, flare magnitude, solar coordinates and assigned active
region for the event. I have removed the flares associated with other Active Regions.
14-Nov-2014 07:42 07:48 07:53 C5.4 S13E80 12209
14-Nov-2014 23:15 23:39 23:58 C2.0 S12E71 12209
15-Nov-2014 06:11 06:14 06:18 C1.1 12209
15-Nov-2014 11:40 12:03 12:10 M3.2 S09E63 12209
15-Nov-2014 20:38 20:46 20:50 M3.7 S13E63 12209
15-Nov-2014 23:33 23:46 00:00 C2.7 S09E47 12209
16-Nov-2014 01:11 01:15 01:21 C1.4 S10E46 12209
16-Nov-2014 07:36 07:46 07:57 C3.9 S12E51 12209
16-Nov-2014 09:07 09:11 09:21 C2.0 S10E47 12209
16-Nov-2014 09:59 10:05 10:10 C2.4 S10E47 12209
16-Nov-2014 13:40 13:43 13:46 C1.5 12209
16-Nov-2014 16:39 16:47 16:55 C3.9 12209
16-Nov-2014 17:35 17:48 17:57 M5.7 12209
16-Nov-2014 22:02 22:06 22:09 C2.4 S12E43 12209
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AR2192 returned as AR2209 in the second half of November 2014
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17-Nov-2014 06:01 06:04 06:06 C1.7 S11E41 12209
17-Nov-2014 18:06 18:30 18:44 C1.6 S11E33 12209
18-Nov-2014 07:49 08:09 08:23 C1.8 S11E25 12209
18-Nov-2014 19:24 19:30 19:37 C1.3 12209
18-Nov-2014 19:49 19:50 19:54 C1.1 12209
19-Nov-2014 18:57 19:03 19:07 C2.4 S13E07 12209
20-Nov-2014 19:36 19:56 20:09 C2.5 S12W08 12209
20-Nov-2014 21:03 21:13 21:29 C1.3 S11W10 12209
21-Nov-2014 01:53 01:58 02:08 C1.4 S11W13 12209
21-Nov-2014 04:41 04:45 04:48 C1.9 S12W14 12209
21-Nov-2014 23:25 23:33 23:39 C1.1 S14W21 12209
22-Nov-2014 00:54 01:01 01:06 C8.1 S12W26 12209
22-Nov-2014 03:35 03:41 03:47 C2.4 S12W27 12209
22-Nov-2014 05:58 06:03 06:07 C6.5 S14W25 12209
22-Nov-2014 06:09 06:14 06:17 C3.2 12209
22-Nov-2014 09:53 09:57 10:04 C1.5 12209
22-Nov-2014 13:09 13:31 13:56 C2.1 S14W33 12209
22-Nov-2014 17:08 17:13 17:19 C3.1 S13W33 12209
23-Nov-2014 05:32 05:39 05:44 C2.4 S12W42 12209
23-Nov-2014 15:37 16:14 16:23 C2.4 S13W47 12209
Above a table of NOAA sunspot data http://hesperia.gsfc.nasa.gov/goes/goes_event_listings/goes_xray_event_list_2014.txt
Solar altitude at mid day on Winter Solstice
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We have now passed through the Winter Solstice [21 December 2014] the lowest altitude of the Sun’s ecliptic plane, the
Sun is only 30 degrees [known as declination angle] above the horizon at my location at 37.2 degrees N at mid day but
we are still fortunate to generally get up to 9 hours of uninterrupted sunshine but the atmospheric seeing is generally
average to poor quality. If you wish to approximately calculate the altitude of the mid day Sun at your location on this
date the formula is 90º - your latitude – 23.45º. The calculation for summer solstice mid day solar altitude is 90º - your
latitude + 23.45º. Here is a useful website for further reading http://pveducation.org/pvcdrom/properties-of-sunlight/
declination-angle
Below is a 12-panel mosaic that I made of the winter solstice H-alpha Sun. I also captured an M1.0 class solar flare on
AR2241 image at 12:03 UT.
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The Sun also released an X1.8-class solar flare associated with AR2242 on the 20
December 2014 here is a GONG data image of this event and a movie using the GONG
data. http://cdn.astrobin.com/images/5610/2014/e00ff2d3-e733-4b15-8308-e1e-
58303af2a.gi
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Article byAndy Devey
THE SOLAR EXPLORER
http://thesolarexplorer.net/
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The Curious Case for Methane on Mars, methane and active
organics discovered on Mars
On December 16, 2014 at the American Geophysical Union con-
ference in San Francisco, a panel of scientists working on the
Mars Science Laboratory (MSL) Curiosity Rover data announced
what we have all been waiting decades to hear. John Grotzinger
stated unequivocally, “…there is methane occasionally present
in the atmosphere of Mars and there are organics preserved
in (…) rocks on Mars.” Why is this important? All life on Earth
that we have discovered so far is carbon based, aka organic.
Carbon is found in the DNA of all life forms on Earth. Carbon
can bind with many other elements to form thousands of mol-
ecules that are involved in biological processes. Needless to
say, finding organics and methane is a game changer for all of
science, from astronomy to zoology. Organics in general refer to
molecules that are often found as components of life. We know
from studying life forms on Earth that methane is a common
organic molecule that is a waste product of bacteria and macro
organisms. In fact approximately 90% of Earth’s methane has
a biological origin. However, about 10% of methane on Earth
is a result of geological activity. According to author Jeffrey
Bennett from the University of Colorado, Boulder, “The amount
Methane molecule by Dr. Susan Rubin
Earth and Mars NASA
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The Curious Case for Methane on Mars, methane and active
organics discovered on Mars
of methane in the atmosphere appears to vary regionally across Mars, and also seems to vary with the Martian
seasons. This has led some scientists to favor a biological origin (…) if the source is volcanic (…) the amount of
(…)heat necessary for methane release [could] be sufficient to maintain pockets of liquid water underground.”
Pockets of liquid water would be conducive to life The Earth and Mars have many similarities including a 24 hour
and 24 hour 37 minute day respectively, a similar axial tilt causing seasons to occur, a rocky surface with many
of the same types of rocks and minerals (which may be used as a source of energy), volcanic activity and hydro-
thermal vents past and/or present, water that is/was fresh, salty, acidic, and/or basic. Now and perhaps most
important of all, organic matter and methane. In addition to the aforementioned facts, the fleet of rovers and
orbiters that have arrived at Mars have proven an environment conducive to microorganisms existed and may
currently exist on the Red Planet. We know this thanks to the many spacecraft that have visited Mars and sent
back ample amounts of data.
The Viking missions were sent to Mars in the mid 1970’s. They
carried a variety of scientific instruments. Some of them sampled
the atmosphere and some examined the regolith. The results of
these experiments have been studied repeatedly since they were
performed. The Labeled Release Experiment, designed by Dr. Gil
Levin, made a controversial and still contested discovery of life
on Mars. Viking also discovered methane at 10.5 parts per billion
(ppb) in 1976. It seems both of these discoveries were discounted
over the past four decades.
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While utilizing the NASA Infrared Telescope in Hawaii, Michael Mumma,
of NASA Goddard, observed methane using ground based instrumenta-
tion in 2003. When he followed up the observations in 2006, the methane
had vanished. Some scientists have stated that is indicative of a seasonal
plume. According to NASA’s astrobiology website Mumma and his team
observed 20-60 ppb of methane near the poles and up to 250 ppb near
the equator. It is interesting to note that the levels of methane are signifi-
cantly higher near the equator where the temperature is higher and possi-
bly more conducive to life. A decade ago the European Space Agency (ESA)
announced they had discovered plumes of seasonal methane on Mars. In
March of 2004,ESA announced that the Planetary Fourier Spectrometer on
Mars Express detected about 10 ppb of methane in the Martian atmosphere.
A spectrometer is a device that “looks” at a sample of something, in this
case atmospheric gases, and takes reading(s) to determine what molecules
make up the sample being observed. A computer generated graph of some
type is then read by scientists to analyze the spectral data.
Although ESA and NASA themselves had previously detected methane on
Mars, it was important to for NASA to continue the search, using the MSL
Curiosity, on the ground in order to again verify the results. The public may
get frustrated with the continuous “discoveries” of methane, but science is
always retesting results to essentially try to “disprove” itself in order to make
sure the facts are real. The Curiosity Rover landed on Mars in August of 2012.
It seemed that almost as soon as the Curiosity Rover started exploring her
new home on Mars she discovered a dry riverbed where fresh water once
flowed in Gale crater. When she drilled into the rock dubbed “John Klein”
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scientists realized that the rock contained what biologists call CHNOPS. That acronym stands for Carbon,
Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur. Those are the six elements needed for all life on Earth
to exist. Another discovery were molecules that included carbon which scientists called “simple organics”.
The most recent and most important discovery includes more complex organic molecules than previously
discovered, such as methane and chlorobenzene. We know Mars is enriched with all of the same chemi-
cals to make life that the Earth has. This latest and greatest discovery puts to rest the long debate about
whether Mars has organics. Some scientists and laymen have been vehemently denying that it is possible.
For the community of “believers” in Martian organics, we feel vindicated.
The amount of methane reported over the past forty years on the Red Planet ranges from 5-250 ppb from
a variety of sources, NASA, ESA, orbiters, rovers, and ground based Earth telescopes. Many peer reviewed
scientific journal articles have been published regarding Martian methane and the possible explanations for
its existence. Some of the potential sources of methane include the presence of life, volcanoes, hydrother-
mal vents, and several other geological processes. Methane breaks up and only has a lifespan of several
decades to 300 years, which is a short time on a planetary scale. It then breaks down into water and carbon
dioxide. That being said, since methane is present on Mars, it must be getting replenished biologically or
geologically currently.
Over the last few decades scientists have discovered amino acids in comets and meteorites, which we know
slam into planets, so it is common sense to see that whether Mars originally had organics or not that organ-
ics would have landed there sometime in the last 4.5 billion years. In 2012 it was announced that even
Mercury has organics on its surface. The moon Enceladus, orbiting Saturn, has organics spewing out of the
ice covered surface from the salty ocean below. It seems that everywhere we look we find organics. We
must ask ourselves, how easy is it to form organics and life? Is life everywhere?
“[A] striking aspect of the Curiosity discovery is that the concentration of methane detected varies sharply
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IMAGE CREDITS :
PAGE 33 Concentrations of Methane ESA
Methane SAM graph NASA
Article By Nicole Willett
over time. That can only be the case if the source
of the methane is locally concentrated, as a globally
spread source could not cause such sharp variations.
Thus, there may be a patch of ground relatively close
to Curiosity which is the source of the emissions,
and, therefore, a prime target to drill in an attempt
to find subsurface life. Similar biologically suspect
spots may well exist elsewhere. We need to locate
such spots, and then send human explorers to drill
and find out what lies beneath,” states Dr. Robert
Zubrin, President of the Mars Society.
~Humans to Mars as a bridge to the stars
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Battlesteads Observatory
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Battlesteads ObservatoryWhen I first walked into the Battlesteads Hotel & Restaurant I already knew I was
somewhere special. The Battlesteads is renowned nationally as a place of fine food,
wine, beer and hospitality with an emphasis on locally sourced produce. When I
met the owner, Richard Slade I thrust out my hand and introduced myself, “Hi, I’m
Roy, I’m a professional astronomer and teacher.” We shook hands, and with a big
smile Richard replied “I’m Richard, and I’m building an observatory.”
Going back in time by a few weeks, I had already made the decision to quit full-time
teaching and start-up a business delivering astronomy events at various places in
the Northumberland Dark Sky Park. Space and the Stars had always had a strong
gravitational pull on me and 2014 seemed like the time to finally go for it. In the
previous year I had been a volunteer at Kielder Observatory and I was the Lead
Astronomer on some events. Kielder Observatory is run in a very particular way
and I felt that I wanted to get out around the region more often, so setting out on
my own, and finding my own path seemed like a great idea. Very quickly I found
myself in demand and was delivering stargazing events in bed and breakfasts,
tipis, yurts, pubs and hotels around Northumberland. Soon enough I became a
Northumberland Park Star Maker which seemed to perfectly suit what I was wanting
to do. You see I don’t just want to do astronomy, I want to teach astronomy skills
to anyone and everyone of all ages and abilities. At the same time I also became
a STEM ambassador and started talking to a couple of educational trusts about a
plan to seed astronomy clubs in schools. Things were slowly gathering momentum
when a useful tip from someone at the Northumberland Park Offices prompted
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me to jump in my car and drive straight over to meet Richard Slade.
We soon got talking and the enthusiasm between us both meant that the smiles never left our faces. Plans
were already in place so the first thing I did was meet the architect, Charles. One Sunday afternoon he popped
over to my house and we spent two hours going over it the plans. I was impressed with the energy and
thought that had gone into it already but it did need some minor tweaks. As things stood the observatory
was going to be facing North mainly to observe the Northern Lights, it would house about 15 people, and
the telescope was nice but probably inadequate for future needs. The overall structure of the building, and
the landscape was perfect. Halfway up a hill in the village of Wark, a wonderful compromise between dark
skies and comfortable access. Constructed out of sustainable materials and with the emphasis on being
a public teaching and experiential observatory, where it is hoped that guests would be able to get their
hands on the equipment and use it with minimal training and support from staff; a truly public observatory.
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Charles the architect re-drew the plans and the observatory was now facing south, and made a lot bigger -
able to house up to 25 people in the “warm room” connecting it. The plan was to keep it to a mainly wooden
construction and the foundations were poured within the week, with half a ton of concrete on EACH ped-
estal holding up the powered sliding observatory roof. Plans for insulation in the observatory room were
abandoned, and it was stripped down to a very basic metal framed wooden construction with plenty of
room for venting to allow the equipment to stay very close to ambient outside temperature. Careful atten-
tion was paid to the comfort of the guests and astronomers and so it was that we turned our attention to
the telescope and equipment.
The first bit of great news was that a coffee machine would be installed; as we know, astronomers are
mainly tea or coffee fuelled. More importantly a 5’x 5’x 5’ hole had been dug for the foundation of the
actual telescope, and since this was a hole dug into solid clay we felt that this would be sturdy enough.
More importantly this was entirely isolated from the rest of the foundations and structure - so you could
remove the entire observatory and it have no impact on the telescope supporting structures. State of the
art power and data utilities were designed in with the observatory being powered from the hotel which
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runs mainly from a 36 panel solar PV tracker in the car park pro-
ducing enough electricity to run the site during daylight hours. This
would be a truly sustainable observatory with no need to resort to
pulling out a dirty old petrol fuelled generator to keep it going half of
the time it’s open. Looking to a connected future, the observatory is
kitted out with enough power points and built in USB charge points
and data connections for guests to power devices and connect to the
internet. We live in an age where a lot of beginner astronomers rely
on smart phones, tables and their associated apps so it made sense
to take care of this. During these conversations Richard mentioned
that he wanted a future-proof outdoor area for people to set up their
own telescopes for observing and astrophotography. Consequently
outdoor power and Cat6 internet-ready cabling was planned in-situ
- no need for guests to bring heavy power packs, and be limited by
their capacity; uploads of images to social media will be able to be
done on the fly.
When we discussed the main telescope, it was clear that the pro-
posed equipment was going to be inadequate for intermediate or
expert astronomers. Additionally the mount that was specified offered
very little future proofing. Discussions were had but budgets were
limited and we also had to take into account that the Battlesteads
Observatory will be user friendly, so buying anything that was overly
complicated and which couldn’t readily be set up and used by guests
was a big no-no. We decided on an EQ8 for its combination of ease
of use and technical prowess, and a Celestron 11” SCT XLT, in our view
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a great mount with potential for the future, combined with a superb
user friendly mid-level telescope. Additionally we were able to secure
an enormous set of 25x100 binoculars on a custom built mount - spe-
cifically for guests who are wheelchair users. It has to be said I’d used
these binoculars before and I can categorically state I’d seen the best
views of the Orion Nebula through these - I have great confidence in
them. The observatory also boasts a few smaller telescopes that guests
can learn to set up and use on our “Get to Know Your Telescope” nights,
and there a binoculars everywhere. I’d learnt previously that if you’ve
got people waiting around to spend time looking through a telescope,
they should be waiting around with binoculars in their hands.
As I type the structure of the observatory is complete and the internal
fitting out will be complete within a week. Landscaping is next, with
Northumberland and UK native plants being the only ones to be used
on and around the site. A stargazers menu is being put together placing
particular emphasis on brunch for astronomers who’ve had a late night,
and dinners for astronomers who want to spend hours as guests. On
top of this - 5 new lodges have been built 25 metres away from the
observatory. These will in time be family rooms with King Sized beds,
and luxury sofa beds for your little astronomers and unlike the main
hotel which is locked up at midnight, guests can come and go as they
please. (The bathrooms have gorgeous whirlpool baths that you can
sample after viewing the whirlpool galaxy!)
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The best bit about all of this, is that Richard shares the same educational vision that I do. The one thing
I always wanted to do was to give astronomy experiences to people, particularly children who could just
never access it either because they couldn’t afford to get up to the Northumberland park or because they
unfortunately lived in environments where experiences like that are just never going to happen. The new
Dark Sky Observatory at the Battlesteads Hotel and Restaurant is going to give a lot back into the commu-
nity and I am in the process of setting up a charity to enable children in these situations to access this expe-
rience completely free. Research suggests that 1 in 5 children in the UK have never seen a forest or a beach
and we want to bring those children to our little corner of the universe in the village of Wark and get them
to look up.
http://www.battlesteads.com/
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contact details
“The Battlesteads Dark Sky Observatory is owned by Battlesteads Hotel and Restaurant and run in partner-
ship with Astro Ventures Limited. A fully featured website booking system will soon be online at www.bat-
tlesteads.com, but in the meantime all inquiries regarding the observatory or other Astro Ventures projects
(including media and bookings), to Roy Alexander on 07931 173 114 or [email protected]”
https://www.facebook.com/DarkSkyObs
https://twitter.com/DarkSky_Obs
http://www.battlesteads.com/
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http://www.awesomeastronomy.com/
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For more information please contact us via our The solar explorer website for price list and
availabilityhttp://thesolarexplorer.net/
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50 COMETS, WHAT ARE THEY?With the right equipment and of course knowledge stunning, astronomical images are produced by the keenest of
amateur astronomers. It is no longer the realm if the professionals to take stunning images of the night sky, equip-
ment such as cameras and telescopes have become more affordable to the general public. In our night skies there are
many wonders, from planets to nebulas. However nothing quite captures the public attention than stunning images of
comets. One such comet in which has been in our skies throughout January is Comet C/2014 Q2 Lovejoy. The comet
is a stunning green-blue colour. (See our gallery of stunning images).
What Is A Comet?
Comets are icy bodies; they are composed of gases, dust and ices. The composition of a comet is typically carbon
dioxide, ammonia, methane and water. In some circles a comet is referred to a ‘dirty snowball.’
Image Source: Image source: http://spaceplace.nasa.
gov/tails-of-wonder/en/
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COMETS, WHAT ARE THEY?
Image Source: Image source: http://spaceplace.nasa.
gov/tails-of-wonder/en/
They are generally formed in the furthest reaches of the solar system, way beyond the orbit of Pluto,
in areas know has the Kuiper belt and Oort cloud. They also orbit the sun; the orbits can vary from
several years to several millions of years. Generally short period orbits are comets from the Kuiper
belt and long period orbits are comets that originate from the Oort cloud. Comets from the Oort cloud
usually come into the solar system because of gravitational perturbations caused by passing stars and
the galactic tide. The galactic type is a tidal force experienced by objects subjected to the gravitational
field of a galaxy, such as the Milky Way.
When a comet approaches our sun, some of the ices melt and volatile gases and dust are released, this
causes an atmosphere around the nucleus, called a coma. When more gases are released the coma
forms a tail. The tail points away from the direction of the sun. Usually there are two tails, one com-
posed of gases (ion tail) and the other composed of dust.
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Currently NASA and the ESA have a spacecraft called Rosetta orbiting the comet 67P Churyumov-Gerasimenko .
Rosetta last year dropped a Lander called Philae onto the comets surface. However the Lander after a few bounces
came to rest near a cliff ridge, which meant the Lander had little chance to get power from the sun. Before Philae
went to sleep data was sent back to earth. Rosetta is still in orbit around the comet and sending back data.
Image Credits: Top: http://www.wisegeek.org/what-is-the-difference-between-a-comet-and-a-meteor.htm#
Opposire: : http://spaceplace.nasa.gov/tails-of-wonder/en/
Article D Bood
Sources: NASA, Wikipedia
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54
A S T R O N E R D S | F E B 2 9 1 5image by Jaspal Chadha- PleiadesLocation: Stratford, LondonThis is a 15 minute exposure in terrible viewing conditions.
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A S T R O N E R D S | F E B 2 0 1 5image by Jaspal Chadha- PleiadesLocation: Stratford, LondonThis is a 15 minute exposure in terrible viewing conditions.
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Why would anyone want to do astrophotography with a regular camera lens instead of a telescope? There
are many reasons. Some objects, like the Milky Way and the Veil Nebula, are too big for the field of view of
most telescopes. A regular lens gives you the flexibility to set up quickly, without the hassle and expense
of a heavy telescope, wires, large batteries, and (for some cameras) a laptop computer, Windows, device
drivers, and software. Wide-field images of the Milky Way or the stars can also be very beautiful. And some-
times you can take more interesting pictures with a regular lens than are possible with a big telescope, such
as a picture of a flock of geese flying in front of the Moon, the optical distortion caused by a jet exhaust,
or the Moon rising over a mountain in Yosemite National Park.
The criteria for a good lens for photographing stars and photographing during daylight are quite different.
In this article I will discuss some of the technical and photographic aspects of selecting and using a camera
lens for astrophotography.
Lens criteria for telescope-free astrophotography
For cameras, there is no dispute that a DSLR camera is as low as you can realistically go if you want to take
good quality pictures at night (although there are some people who still use film cameras, and get good
results). But there’s a great deal of confusion about lenses. Some camera review websites ridicule the idea
of obsessing over lens size. They advise you to just move closer to the subject. That’s great advice if you’re
taking pictures of your dog, which might be three feet away, but when the subject is 1,800,000 light years
away, it’s not really an option. (However, if you have a few billion bucks of taxpayer money lying around,
as NASA does, it’s still very good advice.)
Astrophotography is a science. The golden rule in science is: always make the raw data as good as you
can get it. To do astrophotography well, you’re better off spending money on good lenses than buying a
cheap one and trying to fix the image in Photoshop. Photoshopping your images will only make them look
Astrophotography Without a Telescope
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unnatural. For example, one mistake people often make with Photoshop is to make the background black,
thereby removing all the faint detail from the image. Experienced astrophotographers can spot this instantly
and would diss your image.
That said, it’s possible to
get great results with lenses
costing around a hundred
bucks. The biggest factor
in widefield astrophotogra-
phy is not the lens, but the
amount of light pollution
at your site. The worse the
light pollution, the harder it
is to subtract it out. Image
of a portion of the Milky
Way in the constellation of
Cygnus. This image was made
without a telescope—only an
80-200mm f/2.8D zoom lens
(set at 100mm)on an ordi-
nary tripod, using an unmod-
ified Nikon D7000. A total of
28 5-second exposures, taken in Raw mode at ISO 3200, were combined in software to reduce the amount
of noise. This image was also re-sized and contrast-adjusted. The reddish area in the center-right is the North
America Nebula. Compare this image with the one under Nebulae.
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DistortionBefore I start, let me dispel a few myths. Using a camera lens instead of a telescope will not necessarily make
your task easier. You will have much more trouble with light pollution with a regular lens than with a tele-
scope. You will also have the additional task of making your photograph into an interesting composition.
That’s not usually an option with a telescope. Although many people are attracted to camera lens astropho-
tography because they think it’s cheaper, this is not necessarily so. You can easily spend one or two thou-
sand dollars for a good camera lens. For that amount of money, you could get a very good telescope and a
computerized mount.
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On the other hand, with a camera lens there’s less of a need to be familiar with the sky. You just point in the
general direction of “up” and take your picture. And if you get bored with it, you can use the lenses for other
things, like throwing them at your dog when it barks too much because you’re not taking any pictures of it.
So it’s a good way for beginners to get started.
Coma distortion at the edge of a 35-mm f/1.8 lens at different apertures. This is considered to be an excel-
lent lens, but for star fields it’s only usable when stopped down four steps. A slower lens, such as an f/2.8,
would have to be stopped down four more steps, which means you’re already down to f/4.5. (D7000, 10 sec,
ISO 1600, daylight white balance, re-sized)
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The three factors that are most important in photographing stars are chromatic aberration
(CA), speed, and sharpness.
1)Chromatic aberration Even some lenses labeled ED, which have some elements made of
extra-low dispersion glass, have unacceptable CA. For a landscape photo, CA isn’t too impor-
tant. For stars, what you’ll get is 2 or 3 separate stars in the corners - a red, white and blue
star next to each other. Yes, you can sometimes fix this in software, but it’s a pain. Don’t
waste your time with a non-ED lens.
2)Speed - You need a fast lens. Period. f/1.4 to f/2.8. It should be a good enough lens that
you can use it wide open, or almost wide open. That’s because, in order to get good images,
you’ll have to stop it down, which means longer exposure times. And long exposure times
mean star trailing. The only way to avoid that is to put your cash into a motorized mount
instead of the lens. That costs money. So a slower lens is not really cheaper.
3)Sharpness Ken Rockwell has a wonderful rant about people who are obsessed with sharp-
ness, making it sound like they’re total dorks. But if you photograph the stars, or the moon,
sharpness is critical. Do not buy a lens that is not sharp edge-to-edge. Embrace your inner dork.
Wear the label “dork” with pride. And don’t forget to buy some adhesive tape for your glasses!
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The dispute about sharpness is probably a hold-
over from the old days when people used to print
hard copies of their photos. Even so, it has a point:
because of the optical low-pass filter in almost all
DSLR cameras (the D800E and D7100 being the
only exceptions that I know of ), your images will
always be slightly fuzzy when viewed full-size,
even when they’re taken with a multi-thousand-
dollar lens. To get an artifact-free, sharp image,
it’s usually necessary to reduce it to about half
its original size. I use the “bin pixels - average”
function in Imal for this, because this feature also
reduces the image noise, but it can also be done
in Photoshop.
An articulating screen is a big convenience. I used
to use a portable TV, but they tend to suck up
battery power.
Some other features are important for daytime
photography, but less so for astrophotography:
Un-resized photo of the Moon taken with a Nikkor VR
18-300mm f/3.5-5.6G zoom lens (D7000, 1/100s, f/8,
focal length 300 mm, focus mode manual, ISO 100,
cropped, slight sharpening applied). A better lens
would avoid the chromatic aberration visible here
and give a sharper result.
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Vibration Reduction A tripod or mount and a remote shutter
release are essential for any kind of astrophotography. Vibration
reduction doesn’t help. Leave VR turned off if your lens has it.
Most of my lenses don’t even have it—but then, I learned pho-
tography with an old manual film camera and subsequently
migrated to a Coolpix 880, which was so slow it forced me to
learn the tricks of holding a camera steady (like, for instance,
gluing it to a rock).
Auto-focus Everything we’re talking about here is at “infin-
ity.” The stars are too dim for autofocus to work, so you need
to focus manually. On many cameras, autofocus doesn’t work
when photographing the moon, either. To focus a DSLR, set
the exposure compensation as high as it will go, set the focus
ring to infinity, point at a bright star, use Live View / digital
zoom to focus, and then lock the focus if possible. Older
DSLRs weren’t sensitive enough for this to work, except with a
few bright stars, and it was often a nightmare focusing them,
especially when using a zoom lens. But with the most recent
batch Lens creep distortion in infrared image
Lens creep distortion in infrared image of the planet Jupiter
taken with a zoom lens and no duct tape. Settings: Modified
D90, R72 filter, Nikkor 80-200 f/2.8D, f/3.2, starting focal length
86 mm, 9 sec, ISO 1600. of digital cameras, like Nikon’s D7000,
it has become easy. You kids have it easy.
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Distortion - There are many types of distortion. Pincushion and barrel distortion are not much of a problem.
But coma is a disaster in astrophotography. Pay close attention to lens reviews when people mention “con-
trast.” If a lens has lots of coma, reviewers will sometimes say it lacks contrast. That’s because they don’t
understand what’s happening. Coma changes point sources (like stars) to seagull patterns, especially
around the edges. On a daytime photo, it seems as if you’re losing
contrast. But in fact, a lot of what’s happening is optical distortion
(see image above), mostly spherical aberration and coma.
Geometric distortion can create big headaches when you try to
combine multiple frames. If distortion is present, some parts of the
combined image will not be lined up, causing the image to appear
out of focus. This could happen if the lens is off-center or tilted,
or if there are imperfections in your filter, lens, or camera sensor.
IMAGE LEFT: Lens creep distortion in infrared image of the planet
Jupiter taken with a zoom lens and no duct tape. Settings: Modified
D90, R72 filter, Nikkor 80-200 f/2.8D, f/3.2, starting focal length 86
mm, 9 sec, ISO 1600.
Zoom lenses Zoom lenses tend to zoom by themselves when pointed
straight up. This is called lens creep (see photo above). Typically,
the lens zooms very slowly, at a continuous rate. This can easily be
confused with bad tracking, because it turns stars into long streaks.
So duct tape is essential. Zoom lenses also are hard to set exactly
the same each time. This can make it a challenge to combine shots
taken on different days. Zoom lenses can also be heavy, which can
make it difficult to balance them on a small mount.
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LENSESSo, what is the best lens to use?
As with daytime photography, that
depends on what you want to pho-
tograph. Select your lens on the
basis of how big your object is. A
free Windows program (ccdcalc)
can show you how some popular
astronomical objects fit in the field
of view for various telescopes and
lenses.
Large objects Milky Way, constel-
lations, star trails, meteors—use a
short lens.
Medium-size objects For medium-
sized objects, like the Moon, you
need a long lens. An 8-inch aper-
ture f/10 scope and a DSLR at prime
Satellite trail photographed with Nikkor 50mm f/1.2 lens (D7000, 2 sec, f/2, ISO
4000, cropped, resized to 50% width). This is a crop from a corner of the image,
yet the lens is so good that no CA and very little coma are visible. Satellite trails
are generally fainter than airplane trails, except for big satellites like the ISS.
With experience, it is easy to tell the difference.
focus will fill the entire frame with the Moon almost exactly. You can’t compete with that, even with a top telephoto
lens, but you can fit more earthly objects into the frame. This can make your picture more interesting. Adding a second
object, like a church steeple, a telephone pole, or your dog, can give the picture more atmosphere and artistic appeal.
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Nebulas are good subjects for telescope-free astrophotography, because some of them have angular sizes
many times bigger than the Moon. The only problem is that most nebulas emit their light at 656 nano-
meters, which is almost completely blocked by the camera’s internal filter. To capture that beautiful deep
red glow of recombining hydrogen atoms, you have to have your camera modified for infrared. But some
nebulas, like the Swan Nebula and the Orion Nebula, are bright enough that you can nail them even with
an unmodified camera.
Some star clusters, such as the Pleiades and Hyades, are also big enough that a telephoto lens will work sat-
isfactorily. But the result won’t be as good as if you used a telescope, because a small lens will miss some
of the finer details.
Small objects For galaxies or small star clusters, you need a big telephoto lens to see anything other than
a fuzzy dot. You’re better off leaving these objects to the guys with big telescopes. The only exceptions are
Andromeda and the Large Magellanic Cloud, both of which are much bigger in angular size than the Moon.
Planets are also very small. Photographing planets is a specialized science, and is usually done using a tele-
scope and a special high-speed camera similar to a Webcam.
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With a 70-300mm zoom lens set at 300 mm, the stars are a little brighter than the 35mm lens because of the larger aperture. However, star trailing now becomes a problem. Also, f/4.5 is as far open as this lens will get. At 300mm, it’s only f/5.6. Although it’s not visible here, the stars in the corners are highly dis-torted. In real life, you’d probably have to stop this lens down to f/8 to get acceptable star shapes.
The same lens stopped down to f/4.0. This image would be harder to fix because the signal is fainter, but the camera noise is the same. You would have to take several images and combine them on the computer (using Deep Sky Stacker or some com-mercial software like Nebulosity) to get a noise-free image. These three images in this panel have been resized and converted from 48 to 24 bits/pixel, but not otherwise altered.
A 30-sec exposure of Ursa Major taken with a 35-mm f/1.8 lens on a Nikon D7000 at ISO 1600. Even though the sky looked completely dark to the eye, it appears light brown in this photo because of light pollution. (However, night pho-tographs taken with a D7000 tend to appear a bit more brown than with other cameras.) Correcting this in software would be possible on this image, because there’s lots of signal to work with. This particular image was photobombed by a firefly, which is visible as three yellow streaks in the upper right.
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Camera lenses are measured by their focal length in millimeters. Telescopes are measured by the diameter of their
primary lens or primary mirror in millimeters. To convert, use these formulas:
focal length mm / aperture mm = f-number.
focal length mm / f-number = aperture mm .
The number of photons collected, which determines maximum brightness, is proportional to aperture squared.
Speed, that is, the ability to focus a lot of light efficiently onto a single pixel element, is inversely related to
the f-number. Magnification is proportional to focal length. Resolution is determined by many factors, includ-
ing the turbulence in the atmosphere and the aperture of the lens.
I am most familiar with Nikon lenses, since I’ve used a bunch of them, but Canon lenses are just as good.
Nikons can be used on a Canon, if you add a special adapter, but Canon lenses will not work on a Nikon. Here
is my brief review of some Nikon lenses for telescope-free astrophotography.
Nikkor 28-300mm f/3.5-5.6 (FX)(Aperture = 8-53.6 mm). Some people complain that the focus ring on this
one is too small. At higher zoom it goes down to f/5.6, which means it’s fairly slow. This is a great travel lens,
but it’s not ideal for astrophotography. The difference between f/3.5 and f/1.8 is night and day—literally (see
photos at right).
Nikkor 18-300mm f/3.5-5.6 (DX). This new super-zoom lens is great for daytime use, but probably too slow
for astrophotography. However, at 200mm, the sharpness is almost indistinguishable from the 80-200. The
only difference is that this lens shows some chromatic aberration (see photo of Moon above).
Nikkor 80-200mm f/2.8 (FX)(Aperture 28-71 mm). This lens has no VR but it maintains f/2.8 throughout its
zoom range. And it is sharp! (See photo of Cygnus at top of page).
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Nikkor f/1.8 35mm (DX) (Aperture 19 mm) The best lenses are primes, because you can get them in low
f-numbers, and they are often sharper. This one can be used as low as f/2.2. In my area, the light pollution
turns the sky completely white with this lens in a two-minute exposure. A 35-mm lens on a DX camera is
wide enough to photograph an entire constellation (see photo at right). It’s a nice lens, but it doesn’t have
an aperture ring, and it’s not quite sharp enough, so it’s not recommended for astrophotography. See below
for why an aperture ring is important.
Nikkor f/1.2 50mm (FX) (Aperture 41.6 mm) Even though this lens has no autofocus or vibration reduction,
it’s my favorite lens for astrophotography because it’s fast and amazingly sharp at f/2, even in the corners
(see photo above). It won’t focus past infinity, so your camera has to be in good shape in order to use it. The
focus limitation also limits its use for UV photography, and if you use filters you have to re-focus it for each
wavelength. But despite these limitations, it’s great.
Nikkor f/2.8 60mm (FX) (Aperture 22mm) A prime macro lens that comes with the D90. A little slow for
astrophotography, but usable, and sharp despite not being ED.
Nikkor 70-300 f/4.5-5.6 (FX) (Aperture 15-54 mm) There are two versions of these. The cheap one has lots
and lots of CA. The more expensive one is better, but still too slow.
Nikkor 70-200 f/2.8 (FX) (Aperture 25-71 mm) Another excellent, very sharp lens. So sharp it will cut a big
hole in your bank account and allow all your money to trickle out.
Nikkor 180 f/2.8 (FX) (Aperture mm) A great manual fixed telephoto lens. Sharp edge-to-edge even at
f/2.8. On a camera, the field of view is big enough to fit both halves of the Veil nebula in a single frame
400mm and above For this range, it’s usually better to switch to a telescope. These big telephotos will
make you look like a total dork at a football game and are just as expensive as a high-end refractor scope.
Remember, you can buy a perfectly good 80-mm f/5.0 refractor (focal length = 400 mm) for about 100 bucks.
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The Orion ShortTube rich-field refractor, for instance, weighs 2.95 pounds and is 15 inches long. Compare
that to a Nikkor f/2.8 400mm lens, which has the same focal length but costs over 7,000 bucks and weighs
three times as much. You do get a lot more aperture (142 mm) and presumably less coma (although I haven’t
tested that). But for that price, you could get an Astro-Physics 130mm f/6.3 refractor, a focal reducer, and a
couple of eyepieces and make all the amateur astronomers really hate your guts.
Aperture rings Some lenses don’t have an aperture ring, so the aperture can only be set in the camera. These
kinds of lenses are fine with a DSLR, but they don’t work on CCD astronomy cameras, because most of them
don’t have any way of setting the aperture. If you ever upgrade to an astronomy camera, you’ll have to jam
a piece of plastic into the lens aperture lever to keep it from closing down to f/22. These lenses should be
avoided if you ever plan to move to a cooled CCD camera.
Because FX lens format is bigger, lenses designed for FX are bigger and tend to gather more light, so they’re
generally preferable to DX lenses even on a DX camera. Bigger diameter = more resolution and shorter
exposures.
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Optical Aberrations: Problems and Solutions
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Another common artifact is large red
“stars” that appear in some images and not
in others. These are red strobes from air-
planes, which flash at one-second intervals.
They may be surrounded by a halo caused by
reflections off the fuselage. Long time-expo-
sures of the night sky commonly show many
trails of red and white flashes going in many
directions. If the plane has its landing lights
on, you may see four or more solid lines.
Red halos around stars are very common.
They’re caused when the lens focuses red,
green and blue to different points. Many
camera lenses do this. That’s one reason
monochrome CCD cameras give sharper
images than color cameras: with a mono-
chrome camera you expose one color at a
time, and refocus every time you change
filters.
Long white streaks may be airplanes or satel-
lites. Some satellites, especially Iridium sat-
ellites, show up as a brief flare that resem-
bles a meteor trail. Or they may periodically
get brighter and dimmer if the satellite is
tumbling out of control.
Airplane trails appear as two parallel strings of
beads due to the 1-second wing strobe. The red
center beacon strobe looks like a fuzzy star, but
in this telescope image you can see reflections
from parts of the fuselage. Color noise is also
visible in the background.
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Star sizes and Airy disks
Orion Nebula photographed with a Nikkor 18-300mm lens (left) and a 4.3-inch refractor scope (right). The image on the right has been shrunk to make the star fields the same size. Even with a three-second
exposure, the stars in the left image are not round, and they are larger and fewer in number than the telescope image. Of course, the fact that a tree branch got in the way of the camera doesn’t help, either.
However, the camera image covered a much wider field of view. Also, the telescope image had to be exposed for 39 times longer to get comparable brightness, because the same photons were spread out
over a much wider area on the sensor.
Settings: Left = D7000 on fixed tripod, Nikkor 80-200 f/2.8D at 200 mm, f/3.2, ISO 1600, 49 frames of 3 sec stacked; resized to 1/16 original area, cropped, sharpened and contrast-stretched. Right = modified
D90 on WO FLT-110 + 0.8x reducer/flattener, f/5.6, CGEM, no guiding, total exposure 96 min, resized to 1/159x original area.
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Star sizes and Airy disks
Orion Nebula photographed with a Nikkor 18-300mm lens (left) and a 4.3-inch refractor scope (right). The image on the right has been shrunk to make the star fields the same size. Even with a three-second
exposure, the stars in the left image are not round, and they are larger and fewer in number than the telescope image. Of course, the fact that a tree branch got in the way of the camera doesn’t help, either.
However, the camera image covered a much wider field of view. Also, the telescope image had to be exposed for 39 times longer to get comparable brightness, because the same photons were spread out
over a much wider area on the sensor.
Settings: Left = D7000 on fixed tripod, Nikkor 80-200 f/2.8D at 200 mm, f/3.2, ISO 1600, 49 frames of 3 sec stacked; resized to 1/16 original area, cropped, sharpened and contrast-stretched. Right = modified
D90 on WO FLT-110 + 0.8x reducer/flattener, f/5.6, CGEM, no guiding, total exposure 96 min, resized to 1/159x original area.
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Optically, stars are point sources. However, because of the wave nature of light, an image of a star always appears as a disk, known as an Airy disk, which has a finite size. Several factors determine the size of a star image on your
sensor:
Seeing At high magnification, stars are not found at fixed positions, but move around randomly, due to atmospheric turbulence. This is called seeing and it is measured in the number of arcseconds that the star moves, 2-4 arcsec
being typical.
Aperture The laws of optics say that the diameter of the Airy disk is independent of aperture. However, when you have a wide field of view, there are many more stars on the sensor. When the image is enlarged to the same scale,
the size of a star taken with a small diameter lens becomes proportionately much bigger than the size of a star taken with a large lens. This is a roundabout way of saying that a small diameter lens has less resolution than a large
one. So a telescope will always produce proportionately smaller stars (which is good), but it will also have a narrower field of view (see image of Orion Nebula above).
One result of this is that it’s harder to photograph nebulas with a small lens than a big one because the stars, being proportionally bigger in a small lens, block more of the view.
Focal length the longer the focal length (and therefore magnification), the further apart the photons are spread on your sensor. So, ceteris paribus, it takes proportionately longer to get the same level of exposure as with a short
focal length lens. However, the total amount of energy that’s captured depends almost entirely on the aperture. You can compensate for the long exposure by binning the image, which restores the original concentration of energy.
But binning trades resolution for speed. If you bin the image 2×2, it’s four times brighter, but your image is four times smaller, and you still have the same narrow field of view.
The Cambridge Photographic Star Atlas is a good example of the trade-offs of doing astrophotography without a telescope. Mellinger and Stoyan used a high-end SBIG 16-bit camera and Minolta 50mm f/1.4 lens, stopped down to
f/4, and no telescope, to photograph the stars as seen from both the Northern and Southern hemispheres. The resulting images are spectacular for star fields, but mediocre for nebulae and terrible for galaxies. Photographing small
objects such as galaxies and planets is a challenge with a regular lens, because of its lower resolution. The result is typically a saturated white oblong blob with little or no detail. Even Andromeda and the Large Magellanic Cloud,
which have a large apparent angular size, can be difficult with a small lens.
Next month we wil continue Astrophotography without telescope starting with a look at Mounts.
The article and Images are the work of Thomas J. Nelson
You can view his work here
http://www.randombio.com/
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Optically, stars are point sources. However, because of the wave nature of light, an image of a star always appears as a disk, known as an Airy disk, which has a finite size. Several factors determine the size of a star image on your
sensor:
Seeing At high magnification, stars are not found at fixed positions, but move around randomly, due to atmospheric turbulence. This is called seeing and it is measured in the number of arcseconds that the star moves, 2-4 arcsec
being typical.
Aperture The laws of optics say that the diameter of the Airy disk is independent of aperture. However, when you have a wide field of view, there are many more stars on the sensor. When the image is enlarged to the same scale,
the size of a star taken with a small diameter lens becomes proportionately much bigger than the size of a star taken with a large lens. This is a roundabout way of saying that a small diameter lens has less resolution than a large
one. So a telescope will always produce proportionately smaller stars (which is good), but it will also have a narrower field of view (see image of Orion Nebula above).
One result of this is that it’s harder to photograph nebulas with a small lens than a big one because the stars, being proportionally bigger in a small lens, block more of the view.
Focal length the longer the focal length (and therefore magnification), the further apart the photons are spread on your sensor. So, ceteris paribus, it takes proportionately longer to get the same level of exposure as with a short
focal length lens. However, the total amount of energy that’s captured depends almost entirely on the aperture. You can compensate for the long exposure by binning the image, which restores the original concentration of energy.
But binning trades resolution for speed. If you bin the image 2×2, it’s four times brighter, but your image is four times smaller, and you still have the same narrow field of view.
The Cambridge Photographic Star Atlas is a good example of the trade-offs of doing astrophotography without a telescope. Mellinger and Stoyan used a high-end SBIG 16-bit camera and Minolta 50mm f/1.4 lens, stopped down to
f/4, and no telescope, to photograph the stars as seen from both the Northern and Southern hemispheres. The resulting images are spectacular for star fields, but mediocre for nebulae and terrible for galaxies. Photographing small
objects such as galaxies and planets is a challenge with a regular lens, because of its lower resolution. The result is typically a saturated white oblong blob with little or no detail. Even Andromeda and the Large Magellanic Cloud,
which have a large apparent angular size, can be difficult with a small lens.
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76 LOOK UP- THE NIGHT SKY FOR FEBRUARY 2015FebruaryAs the month starts, the Sun lies within the constellation of
Capricornus, the Sea Goat, until it crosses the border with
Aquarius on the 16th at around 16h, where it remains until
the month’s end.
The MoonThe moon’s perigee (nearest to the earth) occurs
at 07h on the 19th. Apogee (furthest from the
earth) is on the 6th at 06h
February’s Full Moon occurs on the 3rd at 23h10
in the constellation of Cancer.
Last Quarter moon takes place on Feb 12th at
03h51, in Libra.
New Moon is on the 18th at 23h48 in the constel-
lation of Aquarius, passing to the north of the sun.
First Quarter takes place on the 25th at 17h15 in
Taurus, amongst the stars of the Hyades, just 3°
to the west of Aldebaran.
Look out for ‘Earthshine’ illuminating the dark
hemisphere of the waxing crescent moon from
the 19th to the 24th in the early evening sky, and
the waning crescent from the 13th to the 16th in
the early morning sky.
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LOOK UP- THE NIGHT SKY FOR FEBRUARY 2015The Planets
Mercury
During February, Mercury becomes a morning object and reaches its great-
est elongation west (27°) of the sun on the 24th. This is not a particularly good
morning apparition, although for a week before and for a few days after the
greatest elongation, it may be glimpsed using binoculars, very low in the bright-
ening morning twilight. Use the binoculars and scan the SE horizon, where
Mercury may possibly be glimpsed as a twinkling star-like object in the bright
sky. On the 17th, again using binoculars, see if you can observe the extremely
thin crescent moon 3° above the planet.
Throughout February, Venus shines as the glorious ‘Evening Star, known to the
ancients as Hesperus, as evening twilight fades. When the month starts, the
planet sets two hours after the sun, but by the end it is in the western sky for
three hours after sunset. On the evening of the 20th the thin waxing crescent
moon with earthshine illuminating its night hemisphere, will be seen approach-
ing Venus; and at 19h the moon will be 4° to the lower right of the planet. The
fainter object just over a moon width above Venus is the red planet Mars. Two
days later, on the 22nd, this celestial pair, are less than a moon width apart due
to the rapid easterly motion of Venus.
Mars sets 3 hours after the sun as February begins, but a little more than 2 hours
by the month’s end. Look for Mars as mentioned above around the 20th to the
25th, when Venus appears close to Mars in the early evening, in the WSW sky.
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The thin waxing crescent moon in the same vicinity on the 20th and 21st adds its own magic
to this celestial configuration.
Jupiter is at opposition and so culminates (reaches its highest position in the south) at mid-
night on the 6th, and so the giant planet dominates the sky all night long high to the east
of the faint stars which form the pattern of the constellation, Cancer the Crab. During the
month, Jupiter appears to be moving retrograde as the earth overtakes it in their eternal
dance around the sun. Because of its nearest, and so, brightest, the season for observing
the planet with its satellites continues. Therefore sharply focussed, firmly fixed binoculars
will reveal the disc of the planet and the ever-changing positions of the Galilean satellites.
As the evening begins, Jupiter should be looked for in the east, shining steadily and brightly,
and as dawn begins, shining brightly in the west, about to set. Overnight on the 3rd and 4th,
the full moon lies some 5° to the south of Jupiter, forming a pleasing conjunction of the then
two brightest objects in the sky at that time.
Saturn rises just after 03h on the 1st of the month, and if you look low down in the SE sky, an
hour later at 04h, you will see the planet in the constellation of Scorpius which is also rising
at that time. The star you may notice, just less than 1° to the lower right of Saturn is Graffias
(beta Scorpii). At the end of the month Saturn rises at around 01h30, and by this time is visible
throughout the early hours of the morning until dawn. The broad waning crescent moon,
with earthshine illuminating its night hemisphere, may be seen almost 3° to the left of the
‘ringed planet’ on the 13th, when at 04h, they are 10° above the SE horizon.
Uranus sets just before 23h at the beginning of February, but by 21h at the end of the month.
It is an evening object, at the limit of naked eye visibility in the constellation of Pisces, almost
20° east from the centre of the circlet of stars which marks the position of the western ‘fish’.
Beneath this circlet of stars lie both Venus and Mars during the month. If you scan with
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binoculars, some 5° beneath the fourth magnitude star delta Piscium, you should be able to spot
the 6th magnitude planet, since it is the brightest star-like point in that area. Uranus is in a posi-
tion which marks the lower right corner of an isosceles triangle with epsilon and delta Piscium.
Delta Piscium marks the apex of the triangle.
Venus may help you to locate Neptune between 17h30 and 18h on the 1st of February; however
you must use binoculars or a small telescope in order to identify this remote planet. At that
time, on that date, Neptune lies just a little over a moon width to the upper right of Venus. Do
not confuse it with the brighter star sigma Aquarii which lies to the lower right of Venus at the
same angular distance. The three objects form an equilateral triangle, with the faintest object
being Neptune. later in the monthh, on the 26th , Neptune is in conjunction with the sun and
lies far beyond the latter.
There are no major meteor showers during the month, and so we expect to see the normal back-
ground rate of four noticeable meteors during each hour of the night.
Constellations visible in the south around midnight, mid-month, are as follows: Cancer, Leo,
Hydra, with its brightest star Alphard (‘the solitary one’), and the faint constellation of Sextans
the Sextant, to be found just below Leo’s brightest star Regulus.
All times are GMT 1° is one finger width at arm’s length.
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82 BLACK HOLESBlack Holes. Two words that would terrify anyone regardless of their level of interest (or lack of interest)
in science or science fiction. Black holes are places of unimaginable conditions, places where the laws of
physics themselves break down completely. Falling into a black hole would mean absolute and certain
death. That being said, they are also places of an ever-increasing level of intrigue and desire to learn more
about and to study. But what exactly are they?
Picture yourself looking at a star, many times more massive than our own Sun, burning away its fuel pro-
ducing a staggering amount of energy. Then all of a sudden, the star explodes in an incredibly powerful
explosion, shining brighter than a billion suns. After a certain amount of time, which varies depending on
the mass of the star, the explosion slowly starts to get dimmer and dimmer until eventually the only thing
left is a cloud of gas and dust known as a nebula. You then start to move closer to where the star was to
try and see if there is anything left over from the explosion and the next thing you know you are starting
to accelerate faster and faster and faster. You then realise you are caught in the gravitational pull of a black
hole. This is one of the scariest moments a human being could ever encounter because nobody (apart from
Matthew McConaughey of course) knows what happens when you pass through a black hole.
Firstly however, let’s go back to the collapse of the star. A star is essentially a big ball of incredibly hot gas,
and the gas gets hotter and denser the closer to the centre of the star you get. Stars only have a limited
amount of gas to fuel themselves (albeit the amount of fuel they have can be quite extraordinary!) and
thus, at one point in their lives, they will run out. This is how a star dies. Depending on the mass of the star
(our theoretical one being many times greater than our own Sun), the star will either collapse in on itself
and form a white dwarf, or it will collapse so rapidly that it will explode in the greatest single explosive
event throughout the known universe. The star’s outer layers have been blown away and all that is left of
our theoretical star is a black hole.
The moment you started accelerating faster and faster you passed the black hole’s event horizon. Fancy
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name, but don’t let it fool you. A black hole’s event horizon is essentially a sphere that surrounds the black hole
and if you pass into that sphere you will be caught in the gravitational pull of the black hole and there is no escape.
During the descent deeper into the black hole, your body would undergo a process known as “spaghettification”
whereby your body will stretch and stretch and keep stretching until it is nothing but a string of atoms.
At the centre of a black hole lies a spacetime singularity. This is a region of space that is infinitesimally small and
infinitely dense, and it is within this singularity that the laws of physics that have governed our universe since its
birth 13.8 billion years ago, break down completely. Eventually your mass will be added to the mass of the black
hole and you would be crushed into an infinitely dense region of space that has no volume. This is right at the fore-
front of science, we don’t know anything about what happens after this stage. There are people who have their
theories, as there always are – some as extravagant as a portal that connects that black hole to another one else-
where in the universe, or a different universe, or even a different dimension (I’m looking at you Kip Thorne and
Christopher Nolan!). So the big question is… what happens next?
ARTICLE BY LIAM EDWARDS IMAGE: WIKIPEDIA
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RICHARD J BARLETTON AMAZON
CLICK AMAZON ABOVE TO FOLLOW THE LINK
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RICHARD J BARLETTON AMAZON
CLICK AMAZON ABOVE TO FOLLOW THE LINK
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PROJECT:Sending a balloon into the sky with a camera When: Scheduled lift-off in June of 2015 Why: For Science and fun! CA,USA
TWITTER: @Aether_mission
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Ok the Aether mission project is not quite astronomy however it has the potential for some stunning images
of the Earth. Not so long ago there was a man, in the UK I think, who wanted some aerial images of his house.
He tried several methods including a radio controlled plane. After a few trials he purchased a weather balloon,
made a secure box to house the camera and used his mobile phone to track the equipment has it came down
to earth. The images that the camera took were stunning, they showed the Earth’s curve, they were so good
even NASA was impressed. What is interesting is science can be fun and it is open to us all. I hope we are able
to bring you some of the pictures from the project. Good Luck!
Editor: Dave Bod
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