Small Telescope Science Program (STSP) Overview

• STSP Description

STSP is a Pro-Am collaboration for NASA’s Deep Impact (DI) Mission. It is a world-wide network of professional and amateur astronomers willing to obtain CCD images of periodic comet 9P/Tempel 1, the target of DI. On July 4, 2005, one day before perihelion, a 500-kg smart impactor will be launched from a fly-by spacecraft. The impactor is designed to blast a crater, 10-20m deep, in the comet’s nucleus, which is about 5km wide.

This is the first time the interior of a cometary nucleus will be studied, revealing information about its composition and structure.

• STSP Scientific BenefitsBy early 2001, DI’s science team needs accurate, baseline models of the coma brightness and dust activity of Tempel 1 to aid the design of instrument shields, the impactor, and targeting procedures. To develop accurate models, images spanning many days and several months are needed. Unfortunately, Tempel 1 has not been well studied in the past and this type of time-dependent observing is very difficult to schedule at large observatories. However, STSP’s network of world-wide astronomers have the the equipment and the ability to provide the necessary coverage. Resulting CCD images will be analyzed for brightness changes, jets, and other structural features. This information will be used to develop baseline models for Tempel 1.

• STSP Observing ScheduleData for the models must be taken when the sun-comet-earth positions minimize projection effects and provide different viewing geometries. The most useful information is before or after perihelion. Comet Tempel 1 passed perihelion on January 2, 2000, therefore the best time to observe the comet for coma and pre-mission dust information is May 2000 to January 2001. STSP participants can provide additional coma information from January 2004 to May 2004 and January 2005 to July 2005, during the comet’s next apparition. During the interim, we suggest observers remain active in this Pro-Am collaboration by providing CCD images of faint comets as well as near-earth asteroids with comet-like orbits which are probably inactive or dead cometary nuclei.

STSP Observing Requirements and Procedures

• Equipment Requirements– Participants need to use a telescope with stable tracking and

a top-notch CCD camera. We suggest a minimum aperture of 24 centimeters and a minimum focal length of f/4 or f/5. However, more important is to match the CCD’s pixel resolution to the seeing and telescope’s image size while retaining a large field of view.

– Dust characteristics can be analyzed by comparing images made with photometric Visual (V) and Red (R) filters. These filters are also useful for finding jets and and other structural features in the coma. We request participants use the following types of filters when imaging Tempel 1:

• Photometric (Bessel, Kron-Cousins) Visual and Red, or

• Photographic RGB with an infrared-cutoff filter.

– Images made with clear filters will be accepted since these images provide coma brightness information.

• Observing Requirements

We request participants provide the following for each comet Tempel 1 observing run:

– 3 or 5 flat fields for each filter used.

– Unprocessed comet images using the required filters. The comet is moving very rapidly with respect to the background field, so we suggest taking at least 3 short exposures (about 60 seconds). Images should not be added; we need each raw image for consistent data reduction, analysis, and archival.

– 3 or 5 dark frames with the same exposure times as the flat fields and comet images. Separate dark frames are not needed if the participant’s CCD software automatically takes and subtracts a dark frame from each light frame.

– All images in FITS format.

– An observing log which includes seeing and weather conditions, if possible.

STSP Current Participants

Participant Observing Location

Peter Birch Perth Observatory, Western Australia

Hermann Boehnhardt ESO VIT, Chile

Maurice Leonard Clark Quinns Rock, Western Australia

Gary Emerson Colorado, USA

Ignaciao Ferrin Venezuela

Gordon Garradd Tamsworth, New South Wales, Australia

Thomas Johnson South Africa

William Liller Vina del Mar, Chile

Hugh Lund South Africa

Rob McNaught Siding Spring Observatory, New South Wales, Australia

Gianluca Masi Ceccano, Italy

Terry Oswalt Kitt Peak, USA

Tim Puckett Georgia, USA

Pedro Re Cascais, Portugal

Andrew Timko Woomera, South Australia

Tony Virgo Woomera, South Australia

STSP Current Status and Images

• ParticipationFor more complete coverage of comet Tempel 1, we would like to increase the number of astronomers participating in STSP. Since the beginning of this year, Tempel 1 has only been observable from the southern hemisphere during the pre-dawn hours. The comet is now observable from the northern hemisphere during pre-dawn. As the year progresses, Tempel 1 becomes a nighttime object, through January 2001.

• Participant’s Images and AnalysisWe present images taken by some of our current participants. Unless indicated, all images are oriented with north to the top and east to the left. The red arrow ( ) indicates the sunward direction.

Image analysis will begin the Summer of 2000 and continue into early 2001. Our goal is, again, to provide information about magnitude changes and dust features for the development of a baseline model of comet Tempel 1, in support of DI mission design.

Feb 28 18:35 UTObserver: Rob McNaught using a 1.0-m f/8 reflector at Siding Spring Observatory.Exposure: One 40s, photometric R filterField of view: about 4 arcminComments: Unprocessed image corrected only for bias, dark, and flat frames. On this date the comet-earth distance was 1.6AU. Ignoring projection effects, the coma’s diameter is about 1.2x104km and the tail extends about 2.0x105km.

Above, image-processed in search of jets and structural featuresComments: The above image using azimuthal rotation ( 6° ) and subtraction to search for coma features such as jets and fans. The small, bright area beneath the center of the image may indicate a jet. Additional processing will performed this summer to verify if this feature is real or an artifact of image processing.

Feb 28 18:46 UTObserver: Gordon Garradd using a 45cm f/5.4 Newtonian in Tamsworth.Exposure: Two 50s (coadded), no filtersField of view: about 8 arcminComments: Unprocessed image corrected only for bias and dark frames.

Mar 18 09:54 UTObserver: William Liller using a 8in f/1.5 Schmidt camera.Exposure: One11s, no filterField of view: about 16 x 14 arcminComments: Unprocessed image corrected only for bias, dark, and flat frames. Image orientation to be determined.

Tempel 1

May 4 21:49 UTObserver: Peter Birch at Perth Observatory.Exposure: One 300s, clear filterField of view: 2.7 arcminComments: Unprocessed image corrected only for bias. Peter Birch has also provided 2 photometric R images and 1 I image which are not presented here; the comet is very dim without dark and flat frame corrections.

May 2 20:32 UTObserver: Maurice Clark using a 30cm f/4 Newtonian near Perth.Exposure: One 180s, no filtersField of view: about 6 arcminComments: Unprocessed image corrected only for bias, dark, and flat frames.

May 5 21:28 UTObserver: Peter Birch at Perth Observatory.Exposure: One 1500s, clear filterField of view: 2.7 arcminComments: Unprocessed image corrected only for bias. Peter Birch has also provided another clear image and 2 photometric Rimages which are not presented here; the comet is very dim without dark and flat frame corrections.

May 11 18:28 UTObserver: Gordon Garradd using a 45cm f/5.4 Newtonian in Tamsworth.Exposure: One (of 6) 60s, no filtersField of view: 6.8 arcminComments: Unprocessed image corrected only for bias and dark frames.

May 7 18:25 UTObserver: Gordon Garradd using a 45cm f/5.4 Newtonian in Tamsworth.Exposure: Five 60s (coadded), no filtersField of view: 7 arcminComments: Unprocessed image corrected for bias, dark, and flat frames.

Tempel 1

For More Information or How to Join STSP

• Contact stefmcl@astro.umd.edu

• Visit the STSP website at:

http://www.ss.astro.umd.edu/deepimpact/stsp/

• Take a business card and a copy of this poster!