==========================================================================
I/350 Gaia EDR3 (Gaia Collaboration, 2020)
The following files can be converted to FITS (extension .fit or fit.gz)
gaiaedr3.sam agncrid.dat comscanl.dat framers.dat tyc2tdsc.dat
==========================================================================
Query from: http://vizier.cds.unistra.fr/viz-bin/VizieR?-source=I/350
==========================================================================
drwxr-xr-x 317 cats archive 8192 Feb 28 11:16 [Up]
drwxr-xr-x 5 cats archive 4096 Feb 23 13:39 [TAR file]
-rw-r--r-- 1 cats archive 512 Feb 23 13:39 .message
-r--r--r-- 1 cats archive 77663 Feb 23 13:33 ReadMe
-rw-r--r-- 1 cats archive 1005 Feb 23 13:39 +footg5.gif
-rw-r--r-- 1 cats archive 2978 Feb 23 13:39 +footg8.gif
-r--r--r-- 1 cats archive 29789372 Nov 17 2020 agncrid.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html]
-r--r--r-- 1 cats archive 600747398 Nov 5 2020 comscanl.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html]
-rw-r--r-- 1 cats archive 671 Dec 14 2020 custom.htx
-r--r--r-- 1 cats archive 4003685 Nov 5 2020 framers.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html]
-r--r--r-- 1 cats archive 349008 Nov 23 2020 gaiaedr3.sam.gz [Uncompressed]
-r--r--r-- 1 cats archive 195864538 Nov 23 2020 tyc2tdsc.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html]
Beginning of ReadMe :I/350 Gaia EDR3 (Gaia Collaboration, 2020)
================================================================================
Gaia Early Data Release 3 (Gaia EDR3).
Gaia collaboration
<Astron. Astrophys., 649, A1 (2021)>
=2020yCat.1350....0G
=2021A&A...649A...1G
=doi:10.5270/esa-1ugzkg7
================================================================================
ADC_Keywords: Surveys ; Stars, standard ; Positional data ; Proper motions ;
Photometry, photographic ; Cross identifications ;
Radial velocities ; Stars, variable ; Minor planets;
Parallaxes, trigonometric
Mission_Name: Gaia
Keywords: catalogs - astrometry - parallaxes - proper motions -
techniques: photometric - techniques: radial velocities
Abstract:
Gaia DR3 data (both Gaia EDR3 and the full Gaia DR3) are based on data
collected between 25 July 2014 (10:30 UTC) and 28 May 2017 (08:44
UTC), spanning a period of 34 months. As a comparison, Gaia DR2 was
based on 22 months of data and Gaia DR1 was based on observations
collected during the first 14 months of Gaia's routine operational
phase.
Survey completeness:
The Gaia EDR3 catalogue is essentially complete between G=12 and G=17.
The source list for the release is incomplete at the bright end and
has an ill-defined faint magnitude limit, which depends on celestial
position.
The combination of the Gaia scan law coverage and the filtering on
data quality which will be done prior to the publication of Gaia EDR3,
does lead to some regions of the sky displaying source density
fluctuations that reflect the scan law pattern. In addition, small
gaps exist in the source distribution, for instance close to bright
stars.
Astrometry:
The parallax improvement is typically 20% with respect to Gaia DR2.
The proper motions are typically a factor two better than in Gaia DR2.
An overall reduction of systematics has been achieved. E.g., the
parallax zero point deduced from the extragalactic sources is about
-20muas. A tentative correction formula for the parallax zero point
will be provided.
Closer to the release date of Gaia Early Data Release 3, an update
will be given on the astrometry.
Photometry:
The G-band photometric uncertainties are 0.25mmag for G<13, 1mmag
at G=17, and 5mmag at G=20mag.
The GBP-band photometric uncertainties are 1mmag for G<13, 10mmag
at G=17, and 100mmag at G=20mag.
The GRP-band photometric uncertainties are 1mmag for G<13, 5mmag at
G=17, and 50mmag at G=20mag.
Closer to the release date of Gaia Early Data Release 3, an update
will be given on the photometry.
Gaia EDR3 does not contain new radial velocities. The radial
velocities of Gaia Data Release 2 have been added to Gaia EDR3 in
order to ease the combination of spectrosopic and astrometric data.
Radial velocities:
Gaia EDR3 hence contains Gaia DR2 median radial velocities for about
7.21 million stars with a mean G magnitude between 4 and 13 and an
effective temperature (Teff) in the range 3550 to 6900K. The overall
precision of the radial velocities at the bright end is of the order
of 200-300m/s while at the faint end, the overall precision is
1.2km/s for a Teff of 4750K and 3.5km/s for a Teff of 6500K.
Before publication in Gaia EDR3, an additional filtering has been
performed onto the Gaia DR2 radial velocities to remove some 4000
sources that had wrong radial velocities.
Please be aware that the Gaia DR2 values are assigned to the Gaia EDR3
sources through an internal cross-match operation. In total, 10000
Gaia DR2 radial velocities could not be associated to a Gaia EDR3
source.
Astrophysical parameters:
Gaia EDR3 does not contain new astrophysical parameters. Astrophysical
parameters have been published in Gaia DR2 and a new set is expected
to be released with the full Gaia DR3 release.
Variable stars:
Gaia EDR3 does not contain newly classified variable stars. For the
overview of the currently available variable stars from Gaia DR2, have
a look here. Classifications for a larger set of variable stars are
expected with the full Gaia DR3 release.
Solar system objects:
A large set of solar system objects with orbits will become available
with the full Gaia DR3 release. Information on the currently available
asteroids in Gaia DR2 can be found here.
Documentation:
Data release documentation is provided along with each data release in
the form of a downloadable PDF and a webpage. The various chapters of
the documentation have been indexed at ADS allowing them to be cited.
Please visit the Gaia Archive (https://gea.esac.esa.int/archive) to
access this documentation, and make sure to check out all relevant
information given through the documentation overview page
(https://www.cosmos.esa.int/web/gaia-users/archive).
Description:
Contents of Gaia EDR3:
The five-parameter astrometric solution - positions on the sky
(alpha,delta), parallaxes, and proper motions - for around 1.5 billion
(1.5x10^9^) sources, with a limiting magnitude of about G =21 and a
bright limit of about G =3. The astrometric solution will be
accompanied with some new quality indicators, like RUWE, and source
image descriptors.
In addition, two-parameters solutions - positions on the sky
(alpha,delta) - for around 300 million additional sources.
G magnitudes for around 1.8 billion sources.
GBP and GRP magnitudes for around 1.5 billion sources.
Please be aware that the photometric system for the G, GBP, and GRP
bands in Gaia EDR3 is different from the photometric system as used in
Gaia DR2 and Gaia DR1.
Full passband definitions for G, GBP, and GRP. More information will
become available here.
About 1.5 million celestial reference frame (Gaia-CRF) sources.
Cross-matches between Gaia EDR3 sources on the one hand and
Hipparcos-2, Tycho-2 + TDSC merged, 2MASS PSC (merged with 2MASX),
SDSS DR13, Pan-STARRS1 DR1, SkyMapper DR1, GSC 2.3, APASS DR9, RAVE
DR5, allWISE, and URAT-1 data on the other hand.
Additionally, a Gaia EDR3 to Gaia DR2 match will be provided.
Simulated data from Gaia Object Generator (GOG) and Gaia Universe
Model Snapshot (GUMS) will be provided.
The commanded scan law covering the Gaia EDR3 data collection period
will be provided. Also the major periods where data was not sent to
the ground or could not be processed are identified.
Gaia DR3 data (both Gaia EDR3 and the full Gaia DR3) are based on data
collected between 25 July 2014 (10:30 UTC) and 28 May 2017 (08:44
UTC), spanning a period of 34 months. As a comparison, Gaia DR2 was
based on 22 months of data and Gaia DR1 was based on observations
collected during the first 14 months of Gaia's routine operational
phase.
The reference epoch for Gaia DR3 (both Gaia EDR3 and the full Gaia
DR3) is 2016.0. Remember that the reference epoch is different for
each Gaia data release (it was was J2015.5 for Gaia DR2 and J2015.0
for Gaia DR1).
Positions and proper motions are referred to the ICRS, to which the
optical reference frame defined by Gaia EDR3 is aligned. The time
coordinate for Gaia EDR3 is the barycentric coordinate time (TCB).