Solar System object observations. Each table line contains data obtained during the transit of the source on a single CCD, during a single transit. The corresponding epoch is provided. Data not varying within the transit are repeated identically for all single observations of that transit.
All Gaia data processed by the Data Processing and Analysis Consortium comes tagged with a solution identifier. This is a numeric field attached to each table row that can be used to unequivocally identify the version of all the subsystems that were used in the generation of the data as well as the input data used. It is mainly for internal DPAC use but is included in the published data releases to enable end users to examine the provenance of processed data products. To decode a given solution ID visit https://gaia.esac.esa.int/decoder/solnDecoder.jsp
A unique single numerical identifier of the source. Note in particular that these identifiers are by convention negative for SSOs.
Name of the object. It follows the Minor Planet Centre convention for the minor planets. For bundle of observations that are not identified at the time of the data processing, the name is a string like Gaia-DR3SSO-RN where RN is a running number unique to the bundle. For the natural satellites of the major planets, its standard name is given followed by a string (XYY) where X is the first letter of the planetary system it belongs to, and YY is the number of the satellite in Roman numeral.
The transit_id is a unique identifier assigned to each detected (and confirmed) source as it transits the Gaia focal plane. Each time a given source is detected as Gaia scans and re-scans the sky a new transit_id will be created to badge that apparition. Hence the along–scan time and the across–scan position along with the telescope in which the source was detected are used to form a unique integer with which to label the transit.
The several features of a detection that are encoded in transit_id can be easily retrieved using bit masks (&) and shifts () as follows:
On-Board Mission Time line [ns]
= 204800 * ((transit_id 17) & (0x000003FFFFFFFFFF))
Field-of-view = 1 + (transit_id 15) & 0x03 [1 for ‘preceding’ and 2 for ‘following’ fields-of-view respectively]
CCD row = (transit_id 12) & 0x07 [dimensionless, in the range 1 to 7]
Across-scan ‘reference acquisition pixel’ in strip AF1 = (transit_id) & 0x0FFF [pixels] (this is the across-scan centre of the AF1 window and is odd if immediately below the mid-point of the window and even if immediately above)
where the bit mask prefix ‘0x’ denotes hexadecimal.
For further details see Portell et al. (2020). For convenience a decoder for transit_id is available on-line at
Identifier at single CCD level of the observation of a Solar System object. It is unique, and obtained from a combination of transit_id and an integer number representing the CCD strip: OBSERVATION_ID = TRANSIT_ID * 10 + AF CCD number
Minor planet number attributed by the Minor Planet Centre (MPC). It is set to zero for the natural planetary satellites and the candidate new minor planets.
Gaia-centric epoch TCB(Gaia) in JD corresponding to the time of crossing of the fiducial line of the CCD (mid exposure). This is the epoch to which the target coordinates and the position/velocity of Gaia are referred. To avoid loss of precision the reference time J2010.0 has been subtracted.
The error in the Gaiacentric epoch (for both epoch and epoch_utc).
Gaiacentric epoch in UTC in JD-J2010.0 corresponding to right ascension and declination obtained from the conversion of TCB(Gaia) to UTC.
ICRS right ascension of the source as observed by Gaia at epoch, corrected for full relativistic aberration but not for relativistic light deflection in the gravitational field of the Solar System.
ICRS declination of the source as observed by Gaia at epoch, corrected for full relativistic aberration but not for relativistic light deflection in the gravitational field of the Solar System.
Uncertainty on right ascension, systematic component (assumed to be constant during a transit), multiplied by cos of declination.
Standard error for declination, systematic component (assumed to be constant during a transit).
Correlation of ra_error_systematic and dec_error_systematic.
Uncertainty on right ascension, random component, multiplied by cos of declination.
Standard error for declination, random component.
Correlation of ra and dec uncertainty, random component.
G magnitude derived from g_flux.
Average calibrated G flux for the transit.
Error on the average transit-level G flux derived from the individual CCD-level flux measurements of the single transit.
Barycentric equatorial J2000 (ICRS) x position of Gaia at the epoch of the observation.
Barycentric equatorial J2000 y position (ICRS) of Gaia at the epoch of the observation.
Barycentric equatorial J2000 z position (ICRS) of Gaia at the epoch of observation.
Barycentric equatorial J2000 (ICRS) x velocity of Gaia at the epoch of the observation.
Barycentric equatorial J2000 (ICRS) y velocity of Gaia at the epoch of observation.
Barycentric equatorial J2000 (ICRS) z velocity of Gaia at the epoch of observation.
Geocentric equatorial J2000 x position of Gaia at the epoch of observation, in a reference aligned to ICRS.
Geocentric equatorial J2000 y position of Gaia at the epoch of observation in a reference aligned to ICRS.
Geocentric equatorial J2000 z position of Gaia at the epoch of observation in a reference aligned to ICRS.
Geocentric equatorial J2000 x velocity of Gaia at the epoch of observation in a reference aligned to ICRS.
Geocentric equatorial J2000 y velocity of Gaia at the epoch of observation in a reference aligned to ICRS.
Geocentric equatorial J2000 z velocity of Gaia at the epoch of observation in a reference aligned to ICRS.
Position angle of the scan direction at the epoch of observation in the equatorial reference frame. 0 = North direction, /2 = increasing right ascension, pi = South, 3/2 = decreasing right ascension. It is defined as the angle between the AL direction and the direction to the North Pole, at the SSO position, after applying the correction for aberration. As a consequence of this correction for aberration, the AC direction is not strictly perpendicular to the AL direction.
Result of the astrometric processing of the individual CCDs in the transit. Values presently defined:
Good position derived.
No position derived, because no centroid could be determined.
Position rejected a priori, because previous studies have shown that it is unreliable.
Position rejected, because this CCD has some samples that have been eliminated.
Position rejected, because this CCD is affected by an AOCS update.
Position rejected, because this CCD is affected by a non-nominal gating.
Position rejected, because of more than one reason, combination of codes 21–26.
Position rejected as outlier, because this position does not fit on the regression line.
Position rejected, because it does not fulfill the magnitude-uncertainty relation, see documentation.
Position rejected, because the value of distToLastCi is invalid.
Position rejected, because the epoch corresponds to known bad attitude, see documentation.
Position rejected, because no attitude or no calibration is available for the epoch of observation.
Result of the astrometric processing of the transit. Values defined at present are:
The transit contains at least one good position.
Positions derived, but less consistent than expected. This means that the criterion to reject outliers had to be relaxed to find an unambiguous set of consistent positions.
Positions derived, but outlier rejection was not possible because of dramatic loss of precision.
Positions derived, but no future field angles in RP/BP, because no attitude is available for the future epochs (reference epoch + 45, 50 and 55 seconds).