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Nicholas Walton (IoA, University of Cambridge)
Anthony Brown
(Leiden Observatory) Xavier Luri
(University of Barcelona) William O’Mullane
(ESAC, ESA)
The Gaia Data: Science Driven Data Access
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 1
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 2
Gaia: Launch 20 Nov 2013 Post launch performance
meets specifications
Jos De Bruijne (2012 see arXiv1201.3238D)
http://www.rssd.esa.int/index.php?project=GAIA&page=Science_Perfor
mance
Gaia Prepares Arrival in Kourou
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 3
Photo credits: ESA/ C
NES/ A
riancespace
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 4
Detailed chemical composition and vsini Radial velocity &
chemical composition
Simulations - Robin et al: arXiv:1202.0132
The Gaia Sky simultaneous astrometric, photometric and spectroscopic
observations – typically 70 observations over 5 years
• 109 stars to G = 20 • 106-107 galaxies • 500,000 quasars • 3x105 solar system obj • Many 104 exoplanets
Gaia End-of-Mission Parallax Errors
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 5
Figure from http://w
ww
.rssd.esa.int/index.php?project=GA
IA&
page=Science_Performance
1. bright-star regime (calibration errors, CCD saturation) 2. photon-noise regime, with sky-background noise and electronic noise
setting in around G ~ 20 mag (equivalent to V = 20 to 22)
1 2
Non-uniformity over the sky: 70% – 116%
Apply factors of ~ 0.7 and ~ 0.5 for positions and proper motions
Gaia Science Spans Astrophysics
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 6 http
://w
ww
.rssd
.esa
.int/i
ndex
.php
?pro
ject
=GA
IA&
page
=IG
_201
1012
0
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 7
• in our Galaxy … – the distance and velocity distributions of all stellar populations – the spatial and dynamic structure of the disk and halo – its formation history – a detailed mapping of the Galactic dark-matter distribution – a rigorous framework for stellar-structure and evolution theories – a large-scale survey of extra-solar planets (~7,000) – a large-scale survey of Solar-system bodies (~250,000)
• … and beyond – definitive distance standards out to the LMC/SMC – rapid reaction alerts for supernovae and burst sources (~20,000) – quasar detection, redshifts, microlensing structure (~500,000) – fundamental quantities to unprecedented accuracy: e.g. relativistic
light bending due to gravity: PPN σγ ~10-6 (~2×10-5 present)
Gaia: transformational science astrometry + spectrophotometry + spectroscopy
The Gaia Sky
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 8 Simulated view of R136 (Jos de Bruijne and Guido de Marchi
Gaia Data: Large, Rich and Complex
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 9 1% a
ccur
acy
on d
ista
nce
for ~
11 m
illio
n st
ars
10%
acc
urac
y on
dis
tanc
e fo
r ~15
0 m
illio
n st
ars
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 10
Single field-of-view-transit photometric standard errors
Credit: Jos De Bruijne - ESA
Survey capabilities
0.0
0.5
1.0
1.5
2.0
2.5
3.0
BP
counts
(10
3 p
hoto
ns)
40 30 20 10 0sample
400 500 680 900! (nm)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
RP
counts
(10
3 p
hoto
ns)
60 50 40 30 20 10 0sample
640 700 800 9001000! (nm)
More info at www.rssd.esa.int/gaia (‘Science Performance’ button) and in arXiv:1201.3238
6 8 10 12 14 16 18 20 22V [mag]
10
100
1000
End
-of-m
issi
onpa
ralla
xst
anda
rder
ror
[µas
]
B1V
M6Vcalibration noise floor
photo
n noise
non-uniformityover the sky
Figure by Jos de Bruijne
Gaia Archive and data access Early data releases Extra Schloss Ringberg 13.04.2012 - p.4/37
Data products include the full prism spectra as well as integrated fluxes.
Tangential Velocity Precision
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 11
Fig: Fancois Mignard – G
AIA
-CA
-TN-O
CA
-FM-048
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 12
Astrophysical Parametrisation
● The BP and RP spectro-photometric enable a range of stellar parameters to be determined
Credit: Coryn Bailer-Jones See Liu et al 2012
Five-year scanning survey mission: sky-coverage non-uniformity § Average ~70 observations over 5 years (~20% dead time) § Varies over the sky between ~50 and ~130 (~20% dead time)
Crowding: incompleteness at high densities and faint magnitudes § Astrometric limit is ~1,000,000 stars deg-2 (without bright stars) § Up to ~3,000,000 stars deg-2 can be handled
Spatial resolution: unresolved close binaries § Detection depends on separation and magnitude difference
On-board processing: not optimised for extended objects § The paper limit is detection up to 200 mas § In reality, extended objects up to 700 mas are detected
Dynamic range: existence of a bright limit § The paper limit is G = 5.7 mag (V = 6 mag is normally quoted) § The real limit is a bit better (and varies from CCD row to row)
Gaia’s “limitations”
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 13
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 14
Data Release Timeline Constraints
● Launch: current schedule 20th Nov 2013 ● L+6m: voyage to L2/ commissioning/ initialisation ● L+12m: first full sky coverage (6m of nominal scans) ● L+24m: fully non-degenerate solutions for parallaxes
and proper motions (18m of data required) ● Processing, calibration, validation (3-6m) ● Preparation of a data release (3-6m) ● L+6m initialisation phase contains 2m ecliptic pole
scanning (~500 repeat scans over 2x3sq deg) and 6m nominal scans → early flux alerts
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 15
Baseline Gaia Data Release Schedule Each release updates and expands the previous
● L+22m: positions, G-magnitudes (all sky, single stars) proper motions for Hipparcos stars (~50 µarcsec/yr) – the
Hundred Thousand Proper Motions (HTPM) catalogue ● L+28m: + radial velocities for bright stars, two band photometry
and full astrometry (α, δ, ϖ, µα, µδ ) where available for intermediate brightness stars
● L+40m: + first all sky 5 parameter astrometric results (α, δ, ϖ, µα, µδ ) BP/RP data, RVS radial velocities and spectra, astrophysical parameters, orbital solutions short period binaries
● L+65m: + variability, solar system objects, updates on previous releases, source classifications, astrophysical parameters, variable star solutions, epoch photometry
● End+3yr: final data release (thus in 2022/23)
~ 9/15
~ 3/16
~ 3/17
~ 5/19
Gaia Data Access: Guiding Principles
• Effective and efficient access to the Billion source catalogue and related data
• No boundaries – seamless interfaces to related missions and survey data
• Science enabling and visualisation applications • Long term access – data preservation and data re-use • Gaia data access relevant to all users from research
scientists to the wider public
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 16
Building the archive and access system is now underway with requirements from the
community driving its shape and scope
Gaia is a Complex Mission Industry and Science combining to deliver the final data
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 17
DPAC: Data Processing & Analysis Consortium
Building the Gaia Data System DPAC CU9: Gaia Data Access
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 18
Catalogue and Web Portal Services
WP910 CoordinationManagement
Architecture andTechnical Dev.
Doc
um
enta
tion
W
P9
20
Service desk
WP930
Val
idat
ion
WP
94
0
Op
erat
ion
s an
d S
ervi
ces
W
P9
50
Edu
cati
on a
nd
ou
trea
ch
WP
96
0
Sci
ence
En
ablin
g A
pp
.
W
P9
70
Vis
ual
isat
ion
W
P9
80
CU9 Releases
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 19
http://great.ast.cam.ac.uk/Greatwiki/GaiaDataAccess
Defining the Requirements via Community Input
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GUMS: Gaia Universe Model model data in preparation for Gaia
The real sky http://www.cfa.harvard.edu/~rkirshner/MilkyWay.jpg
The simulated sky – G < 20 GUMS-10
Robin et al (2012) arXiv 1202.0132v2
See http://gaia.am.ub.es/GUMS-10/
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 21
GUMS data available now via Strasbourg CDS: VI/137
Realistic Simulated Gaia Data GOG: Gaia Object Generator
• GOG simulations (combined data) to be made available via CU9 and CDS early 2014 • Provide community with access to a realistic
representation of Gaia data
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 22
GOG billion star simulations: left – parallax; right photometry (credit: CU2/Luri)
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 23
Timeline for the data flow: can be quick Alerts data is released in near real-time
16h 8h visibility
backlog real time acquisition Gaia
transmission MOC
transmission SOC
0 24 one operational day
d-1 d d+1 48
Initial Data Treatment
First Look
Science Alerts (Cambridge)
Figure courtesy Francois Mignard, updated by LW+STH- NAW
Madrid, Spain
Astrometry (50 mas) (100 µas) Astrometry
SSA ASA PSA ASA? SSA?
Figure courtesy Francois Mignard, updated by LW+STH Figure courtesy Francois Mignard, updated by
LW+STH
The Gaia-LSST Data Driven Connection
Seamless interoperability of data products
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 24
6.12 A Comparison of Gaia and LSST Surveys
Table 6.6: Adopted Gaia and LSST Performance
Quantity Gaia LSST
Sky Coverage whole sky half sky
Mean number of epochs 70 over 5 yrs 1000 over 10 yrs
Mean number of observations 320a over 5 yrs 1000b over 10 yrs
Wavelength Coverage 320–1050 nm ugrizy
Depth per visit (5�, r band) 20 24.5; 27.5c
Bright limit (r band) 6 16-17
Point Spread Function (arcsec) 0.14⇥0.4 0.70 FWHM
Pixel count (Gigapix) 1.0 3.2
Syst. Photometric Err. (mag) 0.001, 0.0005d 0.005, 0.003e
Syst. Parallax Err. (mas) 0.007f 0.40f
Syst. Prop. Mot. Err. (mas/yr) 0.004 0.14a One transit includes the G-band photometry (data collected over 9 CCDs), BP and RP spec-trophotometry, and measurements by the SkyMapper and RVS instruments.b Summed over all six bands (taken at di↵erent times).c For co-added data, assuming 230 visits.d Single transit and the end-of-mission values for the G band (from SkyMapper; integrated BPand RP photometry will be more than about 3 times less precise).e For single visit and co-added observations, respectively.f Astrometric errors depend on source color. The listed values correspond to a G2V star.
195
Chapter 6: Stellar Populations
Figure 6.26: A comparison of photometric, proper motion and parallax errors for SDSS, Gaia and LSST, as a functionof apparent magnitude r, for a G2V star (we assumed r = G, where G is the Gaia’s broad-band magnitude). Inthe top panel, the curve marked “SDSS” corresponds to a single SDSS observation. The red curves correspond toGaia; the long-dashed curve shows a single transit accuracy, and the dot-dashed curve the end of mission accuracy(assuming 70 transits). The blue curves correspond to LSST; the solid curve shows a single visit accuracy, andthe short-dashed curve shows accuracy for co-added data (assuming 230 visits in the r band). The curve marked“SDSS-POSS” in the middle panel shows accuracy delivered by the proper motion catalog of Munn et al. (2004).In the middle and bottom panels, the long-dashed curves correspond to Gaia, and the solid curves to LSST. Notethat LSST will smoothly extend Gaia’s error vs. magnitude curves four magnitudes fainter. The assumptions usedin these computations are described in the text.
194
Chapter 6: Stellar Populations
Figure 6.26: A comparison of photometric, proper motion and parallax errors for SDSS, Gaia and LSST, as a functionof apparent magnitude r, for a G2V star (we assumed r = G, where G is the Gaia’s broad-band magnitude). Inthe top panel, the curve marked “SDSS” corresponds to a single SDSS observation. The red curves correspond toGaia; the long-dashed curve shows a single transit accuracy, and the dot-dashed curve the end of mission accuracy(assuming 70 transits). The blue curves correspond to LSST; the solid curve shows a single visit accuracy, andthe short-dashed curve shows accuracy for co-added data (assuming 230 visits in the r band). The curve marked“SDSS-POSS” in the middle panel shows accuracy delivered by the proper motion catalog of Munn et al. (2004).In the middle and bottom panels, the long-dashed curves correspond to Gaia, and the solid curves to LSST. Notethat LSST will smoothly extend Gaia’s error vs. magnitude curves four magnitudes fainter. The assumptions usedin these computations are described in the text.
194
Chapter 6: Stellar Populations
Figure 6.26: A comparison of photometric, proper motion and parallax errors for SDSS, Gaia and LSST, as a functionof apparent magnitude r, for a G2V star (we assumed r = G, where G is the Gaia’s broad-band magnitude). Inthe top panel, the curve marked “SDSS” corresponds to a single SDSS observation. The red curves correspond toGaia; the long-dashed curve shows a single transit accuracy, and the dot-dashed curve the end of mission accuracy(assuming 70 transits). The blue curves correspond to LSST; the solid curve shows a single visit accuracy, andthe short-dashed curve shows accuracy for co-added data (assuming 230 visits in the r band). The curve marked“SDSS-POSS” in the middle panel shows accuracy delivered by the proper motion catalog of Munn et al. (2004).In the middle and bottom panels, the long-dashed curves correspond to Gaia, and the solid curves to LSST. Notethat LSST will smoothly extend Gaia’s error vs. magnitude curves four magnitudes fainter. The assumptions usedin these computations are described in the text.
194
See discussion session
Inputting to the Requirements Process • You can add your requirements through the GREAT
wiki pages at http://www.great.ast.cam.ac.uk/Greatwiki/GaiaDataAccess
• The first collection of requirements have set a baseline for the data access system development • See the process and resulting rankings in Brown et al 2012:
http://www.rssd.esa.int/SA/GAIA/docs/library/AB-026.htm
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 25
Additional requirements are welcome – ideas generated at this meeting for instance – please add to wiki above
Find Out More http://gaia.esa.int
12 Sept 2013 Nic Walton - Gaia Data @ LSST, Cambridge 26
ESA/CNES/ARIANESPACE - S. Corvaja, 2011