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Gaiaaus der Sicht eines
”First Look Scientists”
Michael Biermann (ZAH–ARI)
MPIA AstroTechTalk, 16. September 2016
MPIA AstroTechTalk,16.09.16
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 1 / 40
Gaia is an ESA Astrometry Space mission
December 2013 Gaia launchJuly 2014 Start of nominal operationsJune 2019 End of nominal operationsmid 2022 final catalogue
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 2 / 40
What Gaia is about
• Positions, parallaxes, proper motions, magnitudes, colours, ...for > 1 billion stars (20–25 µas at G = 15, 300 µas at G = 20)
• Spectroscopy for 10% of these stars
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 3 / 40
DPAC teamwork to deliver the promise of Gaia:DPAC = Data Processing and Analysis Consortium
10+ years of effort
450 scientists/engineers
160 institutes
24 countries and ESA
6 data processing centres
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 4 / 40
Why having First Look Scientists?
Astrometric space missions like Gaia have to simultaneouslydetermine a tremendous number of (source, attitude, calibration,global) parameters.
To reach the targeted level of precision, many months ofobservational data have to be incorporated in a global, coherent andinterleaved data reduction.
By no means neither the instrument nor the data health can beguaranteed by standard procedures.
Since it is undesirable not to know the measurement precision andinstrument stability until more than half a year of the mission haselapsed, one needs a Detailed First Look.
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 5 / 40
First Look
is the in-depth assessment of scientific data health and quality within1 day after reception of data,
uses science data and satellite housekeeping data,
assists Science Operations Center in solving any occurring problem.
Since Week 2, 2014:
131 FLS & PE Weekly Reports
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 6 / 40
The sad fate of the First-Look Scientist(s):
If you are constantly watching outfor rain and hail,
you risk to miss all the sunny days.
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 7 / 40
The many problems and oddities around Gaia
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Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 8 / 40
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Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 9 / 40
The many problems and oddities around Gaia
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Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 10 / 40
The many problems and oddities around Gaia
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Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 11 / 40
Example I: Detection efficiency (ω Cen)
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 12 / 40
Example I: Detection efficiency (ω Cen)
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 13 / 40
Example I: Detection efficiency (ω Cen)
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 14 / 40
Example II: Image centroid distributions
2D Gaia image (star brighter than G = 13)
1D Gaia image (star fainter than G = 13)
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 15 / 40
Example II: Image centroid distributions
What we expect:
frequency
window pixel coordinate
1 pixel
windowcenter
⊗frequency
window pixel coordinate
=
frequency
window pixel coordinate
And what we get ...
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 16 / 40
Example II: Image centroid distributions
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
36 38 40 42 44 46 36 38 40 42 44 46
frequency
window pixel coordinate
FoV1, G ≥ 16, SM1 1
frequency
window pixel coordinate window pixel coordinate
FoV2, G ≥ 16, SM2 1
window pixel coordinate
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 17 / 40
Example II: Image centroid distributions
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 18 / 40
Example II: Add-on – Spurious detections
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 19 / 40
Example II: Add-on – Spurious detections
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 20 / 40
Example II: Add-on – Spurious detections
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 21 / 40
Example III: Astrometric along-scan scatter
Measure for the astrometric accuracy= astrometric along-scan scatter= width σ of a Gaussian fit
to the astrometric residuals
frequency
εη [mas]
2σ
↪→ target at G = 15.8 mag:330 µas for a single CCD transit.
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 22 / 40
Example III: Astrometric along-scan scatter
0
5000
10000
15000
20000
-5 -4 -3 -2 -1 0 1 2 3 4 5-5 -4 -3 -2 -1 0 1 2 3 4 5
frequency
εη [mas]
FoV1, AF, WC0 ←| |→ 0.0%
frequency
εη [mas] εη [mas]
FoV2, AF, WC0 ←| |→ 0.0%
εη [mas]
bright stars, G < 13
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 23 / 40
Example III: Astrometric along-scan scatter
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
-5 -4 -3 -2 -1 0 1 2 3 4 5-5 -4 -3 -2 -1 0 1 2 3 4 5
frequency
εη [mas]
FoV1, AF, WC1 ←| |→ 0.0%
frequency
εη [mas] εη [mas]
FoV2, AF, WC1 ←| |→ 0.0%
εη [mas]
medium-bright stars, 13 < G < 16
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 24 / 40
Example III: Astrometric along-scan scatter
0
20000
40000
60000
80000
100000
-15 -10 -5 0 5 10 15 -15 -10 -5 0 5 10 15
frequency
εη [mas]
FoV1, AF, WC2 ←| |→ 1.6%
frequency
εη [mas] εη [mas]
FoV2, AF, WC2 ←| |→ 2.0%
εη [mas]
faint stars, G > 16g
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 25 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... ............................................
...................................... ....................................
........
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
jump in the astrometric scatter
refocussing
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 26 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... ............................................
...................................... ....................................
........
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
new FL software release
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 27 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... ............................................
...................................... ....................................
........
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
new FL software
?
target
new FL software release
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 28 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... .............................................................................................
................
...................................... ....................................
.................................................................
........
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
jumps in the astrometric scatter
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 29 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... .............................................................................................
................
..............................................
...................................... ....................................
.................................................................
............................................
..........
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
jumps in the astrometric scatter
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 30 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... .............................................................................................
................
..........................................................
...................................... ....................................
.................................................................
............................................
......................
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
jumps in the astrometric scatter
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 31 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... .............................................................................................
................
..............................................................
....................
...................................... ....................................
.................................................................
............................................
..........................
....................
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
jumps in the astrometric scatter
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 32 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... .............................................................................................
................
..............................................................
....................
...................................... ....................................
.................................................................
............................................
..........................
....................
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
new FL software release
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 33 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... .............................................................................................
................
..............................................................
....................
...................................... ....................................
.................................................................
............................................
..........................
....................
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
Station Keeping Maneuvers
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 34 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... .............................................................................................
................
..............................................................
....................
...................................... ....................................
.................................................................
............................................
..........................
....................
..
astrom
etricALscatter
[mas]
OBMT [rev]
FoV1FoV2
target
Station Keeping Maneuvers
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 35 / 40
Example III: Astrometric along-scan scatter
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
...................................... .............................................................................................
................
..............................................................
....................
...................................... ....................................
.................................................................
............................................
..........................
....................
..
astrom
etricALscatter[m
as]
OBMT [rev]
FoV1FoV2
target
propellant movement
Jumps in astrometric scatter are caused by sudden changes in Gaia’s massmoment of inertia due to propellant movements.
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 36 / 40
Example III: Add-on: micro-clanksWhy hasn’t ODAS reached yet the target precision?
Thermal disturbances↪→ mirror movementof ' 20 Si atoms
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 37 / 40
Example IV: Response lossFrom the very beginning, Gaia suffered from ice contamination.
-0.1
0.0
0.1
0.2
0.3
Res
pons
e lo
ss [m
ag]
260 380 500 620 740 860 980 1100 1220 1340 1460OBMT [rev]
FoV 1FoV 2
SP6 SP1
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 38 / 40
Example IV: Response loss
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
1400 1600 1800 2000 2200 2400 2600 2800 3000
respon
seloss
[mag
]
OBMT [rev]
AF FoV1BP FoV1RP FoV1
AF FoV2BP FoV2RP FoV2
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 39 / 40
Summary
By and large, Gaia is working well and producing tremendousquantities of unprecedented data.
On Sep 14, we (DPAC) have released the first Gaia Data Release.I 2D positions, 2D proper motions and parallaxes of 2 million sources
down to G ' 12 with accuracies of about 0.3 mas and 1 mas/yr.I 2D positions of 1.1 billion sources down to G = 20.7 with a positional
accuracy of about 10 mas or better.I Mean G -band magnitudes for all sources.I Light curves of 3 194 variables (Cepheids, RR Lyrae) around the south
ecliptic pole over 28 days with around 200 epochs.I Special A&A issue. 19 papers.
There are already science papers out based on Gaia DR1.
Gaia DR1 is just an appetiser!20 times more (and three times more accurate) than Hipparcos, butonly 0.2% of Gaia DR2 (Q4 2017).
Michael Biermann Gaia aus FLS Sicht MPIA AstroTechTalk,16.09.16 40 / 40