The 2MASS Survey, 6x and Calibration Scan Point Source WDBs contain 41,029 entries that are positionally associated with the predicted positions of known asteroids, comets, planets or planetary satellites. These sources were identified during scan data processing by determining which known solar system objects were within the boundaries of a 2MASS Tile when it was scanned, and searching for positional correlations between the predicted positions of those objects and extracted 2MASS sources. Section IV.9 contains a description of this procedure, the solar system object ephemerides and position prediction methods used.
Association between predicted solar system object
and 2MASS source positions does not imply a physical identification.
The probability of chance associations with detections of
background stars is significant, particularly in high source
density regions at low galactic latitudes. Background source
"contamination" is discussed in IV.9.b.
Because the full 2MASS WDBs contain a large number of spurious detections
of noise and image artifacts, predicted asteroid, comet, planet or
planetary satellite positions may also be associated by chance with
noise or artifact detections.
The reliability of the 2MASS point source
detections associated with the predicted solar system
object positions is indicated by the WDB reliability flag,
rel, that
is included with each entry in the tables below. This flag describes
the probability that the 2MASS detection is a real source as
opposed to the probability that the association with a specific
source is correct.
The Survey, 6x and Calibration WDB
Known Asteroid Association List gives for each asteroid that
was associated with an extraction in these point source
WDBs, object identification, orbital data used to predict positions and visual
brightness, and abridged WDB data for the source.
All of the asteroid associations from the three data sets are
concatenated into one table, and sorted by asteroid designation.
The data set of origin for each association is indicated in
the "DS" column (S=Survey, 6=6x, C=Calibration).
Cross-reference to the full WDB source entry (and in some cases
the Extended Source WDB) is made via the
pts_key and ext_key columns.
The description of each column
is provided in the table header. Note that the names of
some columns in the table header have been abbreviated from their full
WDB names to save space. The full WDB column names are given in the
definitions in these cases.
Asteroids may have multiple entries in this table because
they were detected more than once during the Survey, 6x and
Calibration observations
and appear in one or more WDBs multiple times. This is especially true
for the Calibration Scan WDBs since some of those fields were
observed up to 36 times each night.
Table 1 - Survey, 6x and Calibration Scan WDB Known Asteroid Association List The Survey, 6x and Calibration
WDB Known Comet Association Lists gives for each comet that
was associated with an extraction in the point source
WDBs, object identification, orbital data used to predict positions and visual
brightness, and abridged WDB data for the source.
All of the comet associations from the two data sets are concatenated
into one table, and sorted by comet name. The data set of origin for
each association is indicated in the "DS" column
(S=Survey, 6=6x, C=Calibration).
Cross-reference to the full PSWDB source entry (and in some cases
the Extended Source WDBs) is made via the
pts_key and ext_key columns.
The description of each column
is provided in the table header. Note that the names of
some columns in the table header have been abbreviated from their full
WDB names to save space. The full WDB column names are given in the
definitions in these cases.
Several comets appear more than once in this table because they
were scanned and detected multiple times in the Survey or Calibration
observations.
Table 2 - Survey, 6x and Calibration
Scan WDB Known Comet Association List The Survey Point Source WDB contains 19 extractions that
are associated with Uranus, Neptune and Pluto, and satellites of these planets
and Jupiter. Jupiter was scanned during Survey operations, but was
so bright that its glare effectively washed out the scan data that covered
it. That region of the sky was reobserved at a later time after Jupiter
had moved on, and Jupiter's scan was not saved in the Working Databases.
Several Jovian satellites were detected in adjacent scans that were preserved,
and their extractions are included in the Survey WDB.
Mars and Saturn were not directly observed by 2MASS, the closest
scans being 2.6 and 1 deg away, respectively.
There are no planet
or planetary satellite detections known to be in the
6x or Calibration WDBs.
Planetary detections were identified during survey, 6x and
calibration scan data processing
by determining which known planets were within the boundaries of
a 2MASS Tile when it was scanned, and searching for positional correlations
between the predicted positions of those objects and extracted 2MASS
sources. Please read IV.9 for
a description of this procedure, for details concerning planet ephemerides
and position prediction, and for important caveats concerning the
associations.
Planetary satellite associations were made manually after
pipeline data processing was complete. Ephemerides for all
of the named moons of Jupiter, Saturn, Uranus and Neptume were
generated for each night of 2MASS operations using the
JPL Horizons system.
Predicted satellite positions on each night were then correlated
with the positions of all extractions in the Survey PSWDB.
Potential associations were then screened by hand to filter
out spurious associations with artifacts, noise, or inertially
fixed background objects.
The Survey Planet and
Planetary Satellite Association
List gives for each planet and satellite
associated with a source in the Survey WDB
object identification, orbital data used to predict positions and visual
brightness, and abridged WDB data for the source.
Cross-reference to the full WDB source entry is made via the
pts_key column.
The description of each column
is provided in the table header. Note that the names of
some columns in the table header have been abbreviated from their full
WDB names to save space. The full WDB column names are given in the
definitions in these cases.
Uranus appears three times in this table, and several of its satellites
appear twice because their positions were scanned and detected multiple
times during the Survey, and thus have multiple entries in the WDB. However,
Uranus was not accurately measured by the point source characterization
because of its large extent. It is not found in the Survey
XSWDB.
Table 3 - Survey WDB Planet and Planetary Satellite Association List
a. Known Asteroid Association Lists
b. Known Comet Association Lists
c. Planet and Planetary Satellite Association Lists
[Last Update: 2006 December 30, by R. Cutri]
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