Appendix 6. Merged Working Database Source Information

3. Merged Database Table Formats

a. Merged Point Source Information Tables

The following table contains brief descriptions of the entries in the Survey, 6x and Calibration Merged Point Source Information Tables. The merged source tables contain the mean positions magnitudes and uncertainties for sources detected multiple times in each of the 2MASS data sets. The merging was carried out using an autocorrelation of the respective databases to identify groups of extractions that are positionally associated with each other, all lying within a 1.5" radius circular region. A number of confirmation statistics are also provided in the tables that can be used to test for source motion and/or variability, and the general quality of the merge. The merging procedure and the derived quantities are described in Section A6.1.

The order of the entries in this table is the same as that presented in the IRSA/GATOR query page for these tables.

The columns in the following table are:

Column Name: The parameter name in the Merged Source Information table. Click on this to go to the section of the Explanatory Supplement where the derivation and/or usage of that parameter is described in more detail.

Format: The ascii-equivalent format of the field in the Merged Point Source Information Table expressed in "C" readable notation. This is useful when parsing the aligned tabular output from IRSA/GATOR. Although the data values will conform to these formats, the actual width of the field in the GATOR output may be padded with extra blank spaces to accommodate column headers. Note that some fields contain null values that will require special handling when parsing tables drawn from IRSA/GATOR output.

Units: The units of the parameter. A value of "---" in this column means that the parameter is dimensionless.

nulls: A "yes" in this column means that this parameter can be null in the Merged Source table. A "no" means that there will always be a value in this column in the table. Note that null values are represented differently in the IRSA/GATOR output and the ascii ftp versions of the Merge Source tables.

Description: A brief description of the parameter and its values.

Column Name Format Units nulls Description

Group Indentifiers, Detection Statistics and Confusion Information

gcntr %10d --- no Unique identifier of the merged group within a given database. This value is set to be the cntr/pts_key value of the "seed" extraction for the group (see A6.2).
The gcntr identifier is given in the individual WDB records for all extractions that are members of merged groups. Links between the cntr/pts_key WDB identifiers of the individual group members and the group identifier, gcntr, are provided in the Survey, 6x and Calibration Merged Point Source Cross-Reference tables.
Note: Gcntr is unique only within a given database. Sources in the Merged Survey, 6x and Calibration Tables with the same gcntr identifiers are not the same object on the sky.

napp %5d --- no Total number of extractions associated with this merged group. This number can be larger than the number of scans covering the group position (spos) because it can include multiple extractions within a scan and because of the approximate nature of spos.

gcnf %1d --- no Merge confusion flag. This column indicates if this merged group contains extractions that were positionally associated with more than one group.

"0,1" - Unconfused. All extractions in this group are associated with only one group.

"2,3" - Confused. One or more of the extractions in this group are associated with more than one merged group. Positions and photometry of confused groups are suspect. Close scrutiny of the group members is advised.

sdet %5d --- no Number of unique scans in which this merged source is detected in any band. If sdet < napp, then the source is artificially split in at least one scan.

Position Information

ra %10.6f deg no Average right ascension of the merged group.
For the Survey and 6x WDBs, this is the variance-weighted average right ascension, computed using the positional uncertainties of each extraction in the group.
For the Calibration WDB, this is the unweighted average right ascension of all extractions in the group.
NOTE: All extractions within a group are used in computing the average right ascension.

dec %10.6f deg no Average declination of the merged group.
For the Survey and 6x WDBs, this is the variance-weighted average declination, computed using the positional uncertainties of each extraction in the group.
For the Calibration WDB, this is the unweighted average declination of all extractions in the group.
NOTE: All extractions within a group are used in computing the average declination.

emj_mrg %10.4f arcsec no Semi-major axis of the average position error ellipse.
For the Survey and 6x WDBs, the position error ellipse parameters are computed from the covariance of the positions of all extractions in the merged group.
For the Calibration WDB, the semi-major axis is the larger of the standard deviation of the mean right ascension or declination. If the right ascension error is larger, then emn_ang=90. If the declination error is larger, then emn_ang=0.

emn_mrg %10.4f arcsec no Semi-minor axis of the average position error ellipse.
For the Survey and 6x WDBs, the position error ellipse parameters are computed from the covariance of the positions of all extractions in the merged group.
For the Calibration WDB, the semi-minor axis is the smaller of the standard deviation of the mean right ascension or declination. If the right ascension error is smaller, then emn_ang=0. If the declination error is smaller, then emn_ang=90.

ean_mrg %3d deg no Position angle of the average position error ellipse (degrees E of N).
For the Survey and 6x WDBs, the position error ellipse parameters are computed from the covariance of the positions of all extractions in the merged group.
For the Calibration WDB, ean_mrg has values of "0" or "90" only. The value indicates whether the standard deviation of the mean right ascension (ean_mrg=90) or declination (ean_mrg=0) is larger.

sep_avg %10.4e deg yes Average radial separation from mean group position for all extractions in the group.

sep_sig %10.4e deg yes Standard deviation of the average radial separation from the mean group position for all extractions in group.

sep_mxfmrg %10.4e deg yes Maximum radial separation from the mean group position of any extraction in the group.

sep_jdmax %10.4e deg yes Radial separation between the positions of the two extractions in the merged group with the earliest and latest detections, based on Julian date.

sep_mxrad %10.4e arcsec yes Radial separation from the mean group position for the extraction associated with largest position 2-dimensional chi-squared statistic.
Note: This column is always null for merged Calibration WDB sources.

chisq_mx2d %10.4e --- yes Maximum 2-dimensional position chi-squared statistic among all extractions in the merged group.

Note: This column is always null for merged Calibration WDB sources.

chisq_grp2d %10.4e --- yes Ensemble 2-dimensional position chi-squared statistic for all extractions in this merged group.
Note: This column is always null for merged Calibration WDB sources.

use_cntr %10d --- yes WDB cntr/pts_key identifier of the extraction in this group that lies farthest from the edge of the scan in which it was detected. This is analogous to the algorithm used to resolve multiply-detected sources during the generation of the All-Sky PSC (V.4). However, this column does not necessarily identify extractions in the Merged Point Source WDBs that were selected for the All-Sky or 6x PSC because not all scans were considered for Catalog selection.
This column is null if all extractions in the group lie within 10" of a scan edge.

smin %5d --- no Minimum number of scans that cover the 1.5" radius circular region centered on the mean position of the group.

smax %5d --- no Maximum number of scans that cover the 1.5" radius circular region centered on the mean position of the group.

spos %5d --- no Estimated number of scans that cover the mean group position. This number is computed assuming that the scan boundaries follow great-circles interpolated between the reconstructed 3-band coverage corners of the scan. Because the true telescope scan path sometimes deviated from great circles, and because reconstructed positions of a source from different scans will be distributed over a finite area, the number of detections of a merged source reported (napp and sdet) can sometimes exceed spos.

Photometric Information

j_mavg %7.4f mag yes Average J magnitude of selected extractions in the merged group. This is computed using the WDB default J magnitudes of all extractions that meet the following criteria:

Have a valid detection in the J-band (rd_flg[1]=1,2,3,4) (no upper limits included)

Have J-band photometric uncertainties in the range 0<j_msig<5

J-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

J-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[1] NOT MATCHES '[A-Zdp]').

The average is computed by first converting the magnitudes of the individual selected extractions to flux units, evaluating the average of the flux distribution, and then converting back into magnitude units.
This column is null if the number of usable J-band detections in this group is zero (j_n=0).
Note: Because upper limits are not included in the average, the average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).

h_mavg %7.4f mag yes Average H magnitude of selected extractions in the merged group. This is computed using the WDB default H magnitudes of all extractions that meet the following criteria:

Have a valid detection in the H-band (rd_flg[2]=1,2,3,4) (no upper limits included)

Have H-band photometric uncertainties in the range 0<h_msig<5

H-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

H-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[2] NOT MATCHES '[A-Zdp]').

The average is computed by first converting the magnitudes of the individual selected extractions to flux units, evaluating the average of the flux distribution, and then converting back into magnitude units.
This column is null if the number of usable H-band detections in this group is zero (h_n=0).
Note: Because upper limits are not included in the average, the average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).

k_mavg %7.4f mag yes Average K_s magnitude of selected extractions in the merged group. This is computed using the WDB default K_s magnitudes of all extractions that meet the following criteria:

Have a valid detection in the K_s-band (rd_flg[3]=1,2,3,4) (no upper limits included)

Have K_s-band photometric uncertainties in the range 0<k_msig<5

K_s-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

K_s-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[3] NOT MATCHES '[A-Zdp]').

The average is computed by first converting the magnitudes of the individual selected extractions to flux units, evaluating the average of the flux distribution, and then converting back into magnitude units.
This column is null if the number of usable K_s-band detections in this group is zero (k_n=0).
Note: Because upper limits are not included in the average, the average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).

j_mstdev %10.4f mag yes Standard deviation of the mean J magnitude for selected extractions in the group.
This column is null if the number of usable J-band detections in the group is zero (j_n=0).
If there is only one usable J-band detection in the group (j_n=1), this column is set to the value of the corrected photometric uncertainty for the default J magnitude (Survey and Calibration WDBs: j_cmsig, 6x WDB: j_msig) for that detection.

h_mstdev %10.4f mag yes Standard deviation of the mean H magnitude for selected extractions in the group.
This column is null if the number of usable H-band detections in the group is zero (h_n=0).
If there is only one usable H-band detection in the group (h_n=1), this column is set to the value of the corrected photometric uncertainty for the default H magnitude (Survey and Calibration WDBs: h_cmsig, 6x WDB: h_msig) for that detection.

k_mstdev %10.4f mag yes Standard deviation of the mean K_s magnitude for selected extractions in the group.
This column is null if the number of usable K_s-band detections in the group is zero (k_n=0).
If there is only one usable K_s-band detection in the group (k_n=1), this column is set to the value of the corrected photometric uncertainty for the default K_s magnitude (Survey and Calibration WDBs: k_cmsig, 6x WDB: k_msig) for that detection.

j_mwavg %7.4f mag yes Inverse-variance-weighted average J magnitude of selected extractions in the merged group. This is computed using the WDB default J magnitudes and uncertainties of all extractions that meet the following criteria:

Have a valid detection in the J-band (rd_flg[1]=1,2,3,4) (no upper limits included)

Have J-band photometric uncertainties in the range 0<j_msig<5

J-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

J-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[1] NOT MATCHES '[A-Zdp]').

The average is computed by first converting the magnitudes and uncertainties of the individual selected extractions to flux units, evaluating the weighted average of the flux distribution, and then converting back into magnitude units.
This column is null if the number of usable J-band detections in this group is zero (j_n=0).
Note: Because upper limits are not included in the average, the weighted average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).

h_mwavg %7.4f mag yes Inverse-variance-weighted average H magnitude of selected extractions in the merged group. This is computed using the WDB default H magnitudes and uncertainties of all extractions that meet the following criteria:

Have a valid detection in the H-band (rd_flg[1]=1,2,3,4) (no upper limits included)

Have H-band photometric uncertainties in the range 0<h_msig<5

H-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

H-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[2] NOT MATCHES '[A-Zdp]').

The average is computed by first converting the magnitudes and uncertainties of the individual selected extractions to flux units, evaluating the weighted average of the flux distribution, and then converting back into magnitude units.
This column is null if the number of usable H-band detections in this group is zero (h_n=0).
Note: Because upper limits are not included in the average, the weighted average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).

k_mwavg %7.4f mag yes Inverse-variance-weighted average K_s magnitude of selected extractions in the merged group. This is computed using the WDB default K_s magnitudes and uncertainties of all extractions that meet the following criteria:

Have a valid detection in the K_s-band (rd_flg[1]=1,2,3,4) (no upper limits included)

Have K_s-band photometric uncertainties in the range 0<k_msig<5

K_s-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

K_s-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[3] NOT MATCHES '[A-Zdp]').

The average is computed by first converting the magnitudes and uncertainties of the individual selected extractions to flux units, evaluating the weighted average of the flux distribution, and then converting back into magnitude units.
This column is null if the number of usable K_s-band detections in this group is zero (k_n=0).
Note: Because upper limits are not included in the average, the weighted average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).

j_mwunc %10.4f mag yes Uncertainty of the inverse-variance-weighted average J magnitude.
This column is null if the number of usable J-band detections in the group is zero (j_n=0).
If there is only one usable J-band detection in the group (j_n=1), this column is set to the value of the corrected photometric uncertainty for the default J magnitude (Survey and Calibration WDBs: j_cmsig, 6x WDB: j_msig) for that detection.

h_mwunc %10.4f mag yes Uncertainty of the inverse-variance-weighted average H magnitude.
This column is null if the number of usable H-band detections in the group is zero (h_n=0).
If there is only one usable H-band detection in the group (h_n=1), this column is set to the value of the corrected photometric uncertainty for the default J magnitude (Survey and Calibration WDBs: h_cmsig, 6x WDB: h_msig) for that detection.

k_mwunc %10.4f mag yes Uncertainty of the inverse-variance-weighted average K_s magnitude.
This column is null if the number of usable K_s-band detections in the group is zero (k_n=0).
If there is only one usable K_s-band detection in the group (k_n=1), this column is set to the value of the corrected photometric uncertainty for the default K_s magnitude (Survey and Calibration WDBs: k_cmsig, 6x WDB: k_msig) for that detection.

j_mchisq %6.2f --- yes Chi-squared statistic for the distribution of selected J-band magnitudes and uncertainties in the merged group.
This column is null if there are fewer than 2 usable J-band measurements in the group.

h_mchisq %6.2f --- yes Chi-squared statistic for the distribution of selected H-band magnitudes and uncertainties in the merged group.
This column is null if there are fewer than 2 usable H-band measurements in the group.

k_mchisq %6.2f --- yes Chi-squared statistic for the distribution of selected H-band magnitudes and uncertainties in the merged group.
This column is null if there are fewer than 2 usable K_s-band measurements in the group.

j_mndev %10.4f --- yes Largest negative deviation from weighted average J magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction.
This column is null if there are fewer than 2 usable J-band measurements in the group.

h_mndev %10.4f --- yes Largest negative deviation from weighted average H magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction.
This column is null if there are fewer than 2 usable H-band measurements in the group.

k_mndev %10.4f --- yes Largest negative deviation from weighted average K_s magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction.
This column is null if there are fewer than 2 usable K_s-band measurements in the group.

j_mxdev %10.4f --- yes Largest positive deviation from weighted average J magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction.
This column is null if there are fewer than 2 usable J-band measurements in the group.

h_mxdev %10.4f --- yes Largest positive deviation from weighted aver age H magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction.
This column is null if there are fewer than 2 usable H-band measurements in the group.

k_mxdev %10.4f --- yes Largest positive deviation from weighted aver age K_s magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction.
This column is null if there are fewer than 2 usable K_s-band measurements in the group.

Counts and Quality Information

j_n %5d --- no Number of extractions used in the average J magnitude computations. This is the subset of all extractions in the group (napp) that meet the following criteria:

Have a valid detection in the J-band (rd_flg[1]=1,2,3,4) (no upper limits included)

Have J-band photometric uncertainties in the range 0<j_msig<5

J-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

J-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[1] NOT MATCHES '[A-Zdp]').

h_n %5d --- no Number of extractions used in the average H magnitude computations. This is the subset of all extractions in the group (napp) that meet the following criteria:

Have a valid detection in the H-band (rd_flg[2]=1,2,3,4) (no upper limits included)

Have J-band photometric uncertainties in the range 0<h_msig<5

H-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

H-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffHaction spike artifact (cc_flg[2] NOT MATCHES '[A-Zdp]').

k_n %5d --- no Number of extractions used in the average K_s magnitude computations. This is the subset of all extractions in the group (napp) that meet the following criteria:

Have a valid detection in the K_s-band (rd_flg[3]=1,2,3,4) (no upper limits included)

Have K_s-band photometric uncertainties in the range 0<k_msig<5

K_s-band detection is not based on a single R1 frame

Extraction falls >10" from its scan edge

K_s-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[3] NOT MATCHES '[A-Zdp]').

j_narts %4d --- no Number of extractions in group that are identified as artifacts in the J-band (cc_flg[1] MATCHES '[A-Z]').

h_narts %4d --- no Number of extractions in group that are identified as artifacts in the H-band (cc_flg[2] MATCHES '[A-Z]').

k_narts %4d --- no Number of extractions in group that are identif ied as artifacts in the K_s-band (cc_flg[3] MATCHES '[A-Z]').

j_nconf %4d --- no Number of extractions in group that are flagged as photometrically confused in the J-band (cc_flg[1] = 'c').

h_nconf %4d --- no Number of extractions in group that are flagged as photometrically confused in the H-band (cc_flg[2] = 'c').

k_nconf %4d --- no Number of extractions in group that are flagged as photometrically confused in the K_s-band (cc_flg[3] = 'c').

j_nr1fr1 %4d --- no Number of extractions in group with default J magnitude drawn from a single R1 frame.

h_nr1fr1 %4d --- no Number of extractions in group with default H magnitude drawn from a single R1 frame.

k_nr1fr1 %4d --- no Number of extractions in group with default K_s magnitude drawn from a single R1 frame.

n_dist %4d --- no Number of extractions in group that lie within 10" of a scan edge.

n_pers %4d --- no Number of extractions in group that are flagged as affected by latent image artifacts in any band (cc_flg MATCHES 'p').

n_spike %4d --- no Number of extractions in group that are flagged as affected by diffraction spike artifacts in any band (cc_flg MATCHES 'd').

ce_flg %1d --- no Overall quality flag (caveat emptor) of merged source information based on positions, photometry and artifact flagging of all extractions in group.

"0": All extractions in group fall well away from scan edges and are not flagged as artifacts or confused.

"1": One or more extractions in group has non-zero values of [jhk]_narts, [jhk]_nconf, [jhk]_nr1fr1, n_dist, n_pers or n_spike. The individual extractions going into this group should be scrutinized.

n_galcontam %4d --- no Number of extractions in group that have gal_contam > 0. This indicates that this source is resolved in one or more scans in which it was observed, or is identified as part of a larger extended source.
Caution- The dispersion in "point source" measured magnitudes and positions of resolved sources is systematically larger than for true point sources.

rel_avg %c --- no Average reliability score for all extractions in the group. This is computed by converting the reliability score (rel) to an integer between 1 and 5 (rel=F and A, respectively), averaging the integers, and converting back into a letter score. Averages with fractional parts >0.5 were rounded up to the nearest integer, otherwise they were rounded down.

Column Name	Format	Units	nulls	Description
Group Indentifiers, Detection Statistics and Confusion Information
gcntr	%10d	---	no	Unique identifier of the merged group within a given database. This value is set to be the cntr/pts_key value of the "seed" extraction for the group (see A6.2). The gcntr identifier is given in the individual WDB records for all extractions that are members of merged groups. Links between the cntr/pts_key WDB identifiers of the individual group members and the group identifier, gcntr, are provided in the Survey, 6x and Calibration Merged Point Source Cross-Reference tables. Note: Gcntr is unique only within a given database. Sources in the Merged Survey, 6x and Calibration Tables with the same gcntr identifiers are not the same object on the sky.
napp	%5d	---	no	Total number of extractions associated with this merged group. This number can be larger than the number of scans covering the group position (spos) because it can include multiple extractions within a scan and because of the approximate nature of spos.
gcnf	%1d	---	no	Merge confusion flag. This column indicates if this merged group contains extractions that were positionally associated with more than one group. "0,1" - Unconfused. All extractions in this group are associated with only one group. "2,3" - Confused. One or more of the extractions in this group are associated with more than one merged group. Positions and photometry of confused groups are suspect. Close scrutiny of the group members is advised.
sdet	%5d	---	no	Number of unique scans in which this merged source is detected in any band. If sdet < napp, then the source is artificially split in at least one scan.
Position Information
ra	%10.6f	deg	no	Average right ascension of the merged group. For the Survey and 6x WDBs, this is the variance-weighted average right ascension, computed using the positional uncertainties of each extraction in the group. For the Calibration WDB, this is the unweighted average right ascension of all extractions in the group. NOTE: All extractions within a group are used in computing the average right ascension.
dec	%10.6f	deg	no	Average declination of the merged group. For the Survey and 6x WDBs, this is the variance-weighted average declination, computed using the positional uncertainties of each extraction in the group. For the Calibration WDB, this is the unweighted average declination of all extractions in the group. NOTE: All extractions within a group are used in computing the average declination.
emj_mrg	%10.4f	arcsec	no	Semi-major axis of the average position error ellipse. For the Survey and 6x WDBs, the position error ellipse parameters are computed from the covariance of the positions of all extractions in the merged group. For the Calibration WDB, the semi-major axis is the larger of the standard deviation of the mean right ascension or declination. If the right ascension error is larger, then emn_ang=90. If the declination error is larger, then emn_ang=0.
emn_mrg	%10.4f	arcsec	no	Semi-minor axis of the average position error ellipse. For the Survey and 6x WDBs, the position error ellipse parameters are computed from the covariance of the positions of all extractions in the merged group. For the Calibration WDB, the semi-minor axis is the smaller of the standard deviation of the mean right ascension or declination. If the right ascension error is smaller, then emn_ang=0. If the declination error is smaller, then emn_ang=90.
ean_mrg	%3d	deg	no	Position angle of the average position error ellipse (degrees E of N). For the Survey and 6x WDBs, the position error ellipse parameters are computed from the covariance of the positions of all extractions in the merged group. For the Calibration WDB, ean_mrg has values of "0" or "90" only. The value indicates whether the standard deviation of the mean right ascension (ean_mrg=90) or declination (ean_mrg=0) is larger.
sep_avg	%10.4e	deg	yes	Average radial separation from mean group position for all extractions in the group.
sep_sig	%10.4e	deg	yes	Standard deviation of the average radial separation from the mean group position for all extractions in group.
sep_mxfmrg	%10.4e	deg	yes	Maximum radial separation from the mean group position of any extraction in the group.
sep_jdmax	%10.4e	deg	yes	Radial separation between the positions of the two extractions in the merged group with the earliest and latest detections, based on Julian date.
sep_mxrad	%10.4e	arcsec	yes	Radial separation from the mean group position for the extraction associated with largest position 2-dimensional chi-squared statistic. Note: This column is always null for merged Calibration WDB sources.
chisq_mx2d	%10.4e	---	yes	Maximum 2-dimensional position chi-squared statistic among all extractions in the merged group. Note: This column is always null for merged Calibration WDB sources.
chisq_grp2d	%10.4e	---	yes	Ensemble 2-dimensional position chi-squared statistic for all extractions in this merged group. Note: This column is always null for merged Calibration WDB sources.
use_cntr	%10d	---	yes	WDB cntr/pts_key identifier of the extraction in this group that lies farthest from the edge of the scan in which it was detected. This is analogous to the algorithm used to resolve multiply-detected sources during the generation of the All-Sky PSC (V.4). However, this column does not necessarily identify extractions in the Merged Point Source WDBs that were selected for the All-Sky or 6x PSC because not all scans were considered for Catalog selection. This column is null if all extractions in the group lie within 10" of a scan edge.
smin	%5d	---	no	Minimum number of scans that cover the 1.5" radius circular region centered on the mean position of the group.
smax	%5d	---	no	Maximum number of scans that cover the 1.5" radius circular region centered on the mean position of the group.
spos	%5d	---	no	Estimated number of scans that cover the mean group position. This number is computed assuming that the scan boundaries follow great-circles interpolated between the reconstructed 3-band coverage corners of the scan. Because the true telescope scan path sometimes deviated from great circles, and because reconstructed positions of a source from different scans will be distributed over a finite area, the number of detections of a merged source reported (napp and sdet) can sometimes exceed spos.
Photometric Information
j_mavg	%7.4f	mag	yes	Average J magnitude of selected extractions in the merged group. This is computed using the WDB default J magnitudes of all extractions that meet the following criteria: Have a valid detection in the J-band (rd_flg[1]=1,2,3,4) (no upper limits included) Have J-band photometric uncertainties in the range 0<j_msig<5 J-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge J-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[1] NOT MATCHES '[A-Zdp]'). The average is computed by first converting the magnitudes of the individual selected extractions to flux units, evaluating the average of the flux distribution, and then converting back into magnitude units. This column is null if the number of usable J-band detections in this group is zero (j_n=0). Note: Because upper limits are not included in the average, the average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).
h_mavg	%7.4f	mag	yes	Average H magnitude of selected extractions in the merged group. This is computed using the WDB default H magnitudes of all extractions that meet the following criteria: Have a valid detection in the H-band (rd_flg[2]=1,2,3,4) (no upper limits included) Have H-band photometric uncertainties in the range 0<h_msig<5 H-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge H-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[2] NOT MATCHES '[A-Zdp]'). The average is computed by first converting the magnitudes of the individual selected extractions to flux units, evaluating the average of the flux distribution, and then converting back into magnitude units. This column is null if the number of usable H-band detections in this group is zero (h_n=0). Note: Because upper limits are not included in the average, the average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).
k_mavg	%7.4f	mag	yes	Average K_s magnitude of selected extractions in the merged group. This is computed using the WDB default K_s magnitudes of all extractions that meet the following criteria: Have a valid detection in the K_s-band (rd_flg[3]=1,2,3,4) (no upper limits included) Have K_s-band photometric uncertainties in the range 0<k_msig<5 K_s-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge K_s-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[3] NOT MATCHES '[A-Zdp]'). The average is computed by first converting the magnitudes of the individual selected extractions to flux units, evaluating the average of the flux distribution, and then converting back into magnitude units. This column is null if the number of usable K_s-band detections in this group is zero (k_n=0). Note: Because upper limits are not included in the average, the average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).
j_mstdev	%10.4f	mag	yes	Standard deviation of the mean J magnitude for selected extractions in the group. This column is null if the number of usable J-band detections in the group is zero (j_n=0). If there is only one usable J-band detection in the group (j_n=1), this column is set to the value of the corrected photometric uncertainty for the default J magnitude (Survey and Calibration WDBs: j_cmsig, 6x WDB: j_msig) for that detection.
h_mstdev	%10.4f	mag	yes	Standard deviation of the mean H magnitude for selected extractions in the group. This column is null if the number of usable H-band detections in the group is zero (h_n=0). If there is only one usable H-band detection in the group (h_n=1), this column is set to the value of the corrected photometric uncertainty for the default H magnitude (Survey and Calibration WDBs: h_cmsig, 6x WDB: h_msig) for that detection.
k_mstdev	%10.4f	mag	yes	Standard deviation of the mean K_s magnitude for selected extractions in the group. This column is null if the number of usable K_s-band detections in the group is zero (k_n=0). If there is only one usable K_s-band detection in the group (k_n=1), this column is set to the value of the corrected photometric uncertainty for the default K_s magnitude (Survey and Calibration WDBs: k_cmsig, 6x WDB: k_msig) for that detection.
j_mwavg	%7.4f	mag	yes	Inverse-variance-weighted average J magnitude of selected extractions in the merged group. This is computed using the WDB default J magnitudes and uncertainties of all extractions that meet the following criteria: Have a valid detection in the J-band (rd_flg[1]=1,2,3,4) (no upper limits included) Have J-band photometric uncertainties in the range 0<j_msig<5 J-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge J-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[1] NOT MATCHES '[A-Zdp]'). The average is computed by first converting the magnitudes and uncertainties of the individual selected extractions to flux units, evaluating the weighted average of the flux distribution, and then converting back into magnitude units. This column is null if the number of usable J-band detections in this group is zero (j_n=0). Note: Because upper limits are not included in the average, the weighted average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).
h_mwavg	%7.4f	mag	yes	Inverse-variance-weighted average H magnitude of selected extractions in the merged group. This is computed using the WDB default H magnitudes and uncertainties of all extractions that meet the following criteria: Have a valid detection in the H-band (rd_flg[1]=1,2,3,4) (no upper limits included) Have H-band photometric uncertainties in the range 0<h_msig<5 H-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge H-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[2] NOT MATCHES '[A-Zdp]'). The average is computed by first converting the magnitudes and uncertainties of the individual selected extractions to flux units, evaluating the weighted average of the flux distribution, and then converting back into magnitude units. This column is null if the number of usable H-band detections in this group is zero (h_n=0). Note: Because upper limits are not included in the average, the weighted average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).
k_mwavg	%7.4f	mag	yes	Inverse-variance-weighted average K_s magnitude of selected extractions in the merged group. This is computed using the WDB default K_s magnitudes and uncertainties of all extractions that meet the following criteria: Have a valid detection in the K_s-band (rd_flg[1]=1,2,3,4) (no upper limits included) Have K_s-band photometric uncertainties in the range 0<k_msig<5 K_s-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge K_s-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[3] NOT MATCHES '[A-Zdp]'). The average is computed by first converting the magnitudes and uncertainties of the individual selected extractions to flux units, evaluating the weighted average of the flux distribution, and then converting back into magnitude units. This column is null if the number of usable K_s-band detections in this group is zero (k_n=0). Note: Because upper limits are not included in the average, the weighted average magnitude will systematically overestimate the brightness of faint sources near the sensitivity limit of the observations that are detected fewer times than are possible (sdet<spos).
j_mwunc	%10.4f	mag	yes	Uncertainty of the inverse-variance-weighted average J magnitude. This column is null if the number of usable J-band detections in the group is zero (j_n=0). If there is only one usable J-band detection in the group (j_n=1), this column is set to the value of the corrected photometric uncertainty for the default J magnitude (Survey and Calibration WDBs: j_cmsig, 6x WDB: j_msig) for that detection.
h_mwunc	%10.4f	mag	yes	Uncertainty of the inverse-variance-weighted average H magnitude. This column is null if the number of usable H-band detections in the group is zero (h_n=0). If there is only one usable H-band detection in the group (h_n=1), this column is set to the value of the corrected photometric uncertainty for the default J magnitude (Survey and Calibration WDBs: h_cmsig, 6x WDB: h_msig) for that detection.
k_mwunc	%10.4f	mag	yes	Uncertainty of the inverse-variance-weighted average K_s magnitude. This column is null if the number of usable K_s-band detections in the group is zero (k_n=0). If there is only one usable K_s-band detection in the group (k_n=1), this column is set to the value of the corrected photometric uncertainty for the default K_s magnitude (Survey and Calibration WDBs: k_cmsig, 6x WDB: k_msig) for that detection.
j_mchisq	%6.2f	---	yes	Chi-squared statistic for the distribution of selected J-band magnitudes and uncertainties in the merged group. This column is null if there are fewer than 2 usable J-band measurements in the group.
h_mchisq	%6.2f	---	yes	Chi-squared statistic for the distribution of selected H-band magnitudes and uncertainties in the merged group. This column is null if there are fewer than 2 usable H-band measurements in the group.
k_mchisq	%6.2f	---	yes	Chi-squared statistic for the distribution of selected H-band magnitudes and uncertainties in the merged group. This column is null if there are fewer than 2 usable K_s-band measurements in the group.
j_mndev	%10.4f	---	yes	Largest negative deviation from weighted average J magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction. This column is null if there are fewer than 2 usable J-band measurements in the group.
h_mndev	%10.4f	---	yes	Largest negative deviation from weighted average H magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction. This column is null if there are fewer than 2 usable H-band measurements in the group.
k_mndev	%10.4f	---	yes	Largest negative deviation from weighted average K_s magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction. This column is null if there are fewer than 2 usable K_s-band measurements in the group.
j_mxdev	%10.4f	---	yes	Largest positive deviation from weighted average J magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction. This column is null if there are fewer than 2 usable J-band measurements in the group.
h_mxdev	%10.4f	---	yes	Largest positive deviation from weighted aver age H magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction. This column is null if there are fewer than 2 usable H-band measurements in the group.
k_mxdev	%10.4f	---	yes	Largest positive deviation from weighted aver age K_s magnitude among all extractions in the group, scaled by the photometric uncertainty of the extraction. This column is null if there are fewer than 2 usable K_s-band measurements in the group.
Counts and Quality Information
j_n	%5d	---	no	Number of extractions used in the average J magnitude computations. This is the subset of all extractions in the group (napp) that meet the following criteria: Have a valid detection in the J-band (rd_flg[1]=1,2,3,4) (no upper limits included) Have J-band photometric uncertainties in the range 0<j_msig<5 J-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge J-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[1] NOT MATCHES '[A-Zdp]').
h_n	%5d	---	no	Number of extractions used in the average H magnitude computations. This is the subset of all extractions in the group (napp) that meet the following criteria: Have a valid detection in the H-band (rd_flg[2]=1,2,3,4) (no upper limits included) Have J-band photometric uncertainties in the range 0<h_msig<5 H-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge H-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffHaction spike artifact (cc_flg[2] NOT MATCHES '[A-Zdp]').
k_n	%5d	---	no	Number of extractions used in the average K_s magnitude computations. This is the subset of all extractions in the group (napp) that meet the following criteria: Have a valid detection in the K_s-band (rd_flg[3]=1,2,3,4) (no upper limits included) Have K_s-band photometric uncertainties in the range 0<k_msig<5 K_s-band detection is not based on a single R1 frame Extraction falls >10" from its scan edge K_s-band is not identified as any type of image artifact, and is not flagged as being affected by a nearby latent image or diffraction spike artifact (cc_flg[3] NOT MATCHES '[A-Zdp]').
j_narts	%4d	---	no	Number of extractions in group that are identified as artifacts in the J-band (cc_flg[1] MATCHES '[A-Z]').
h_narts	%4d	---	no	Number of extractions in group that are identified as artifacts in the H-band (cc_flg[2] MATCHES '[A-Z]').
k_narts	%4d	---	no	Number of extractions in group that are identif ied as artifacts in the K_s-band (cc_flg[3] MATCHES '[A-Z]').
j_nconf	%4d	---	no	Number of extractions in group that are flagged as photometrically confused in the J-band (cc_flg[1] = 'c').
h_nconf	%4d	---	no	Number of extractions in group that are flagged as photometrically confused in the H-band (cc_flg[2] = 'c').
k_nconf	%4d	---	no	Number of extractions in group that are flagged as photometrically confused in the K_s-band (cc_flg[3] = 'c').
j_nr1fr1	%4d	---	no	Number of extractions in group with default J magnitude drawn from a single R1 frame.
h_nr1fr1	%4d	---	no	Number of extractions in group with default H magnitude drawn from a single R1 frame.
k_nr1fr1	%4d	---	no	Number of extractions in group with default K_s magnitude drawn from a single R1 frame.
n_dist	%4d	---	no	Number of extractions in group that lie within 10" of a scan edge.
n_pers	%4d	---	no	Number of extractions in group that are flagged as affected by latent image artifacts in any band (cc_flg MATCHES 'p').
n_spike	%4d	---	no	Number of extractions in group that are flagged as affected by diffraction spike artifacts in any band (cc_flg MATCHES 'd').
ce_flg	%1d	---	no	Overall quality flag (caveat emptor) of merged source information based on positions, photometry and artifact flagging of all extractions in group. "0": All extractions in group fall well away from scan edges and are not flagged as artifacts or confused. "1": One or more extractions in group has non-zero values of [jhk]_narts, [jhk]_nconf, [jhk]_nr1fr1, n_dist, n_pers or n_spike. The individual extractions going into this group should be scrutinized.
n_galcontam	%4d	---	no	Number of extractions in group that have gal_contam > 0. This indicates that this source is resolved in one or more scans in which it was observed, or is identified as part of a larger extended source. Caution- The dispersion in "point source" measured magnitudes and positions of resolved sources is systematically larger than for true point sources.
rel_avg	%c	---	no	Average reliability score for all extractions in the group. This is computed by converting the reliability score (rel) to an integer between 1 and 5 (rel=F and A, respectively), averaging the integers, and converting back into a letter score. Averages with fractional parts >0.5 were rounded up to the nearest integer, otherwise they were rounded down.

[Last Updated: 2006 September 28; by S. Wheelock & R. Cutri]

Back to A6.3
Return to Explanatory Supplement TOC Page.