2MAPPS Software Interface Specification DBM21 1.2 99/04/01 Interface Name: DBMAN/DB Point Source Catalog Interface Type of Interface: Database (Informix) Field Data Specification Written By: CATFORM _______________________________ R. Cutri Read By: Informix DB Description: The 2MASS data catalog tables are created from the "working DB" tables in the Informix 2MASS database. This SIS describes the DB fields (AKA "table columns") for the point source catalog table. Descriptions of the extended source catalog table and other DB data are found in the other DBMxx SISs. The DB catalog table containing this data is named "pts_src_cat". It is found in the "tmasss" release DB. If a field is not applicable or contains a "bad or N/A measurement value" (see previous 2MAPPS SISs for details) for a certain source, the field will contain "NULL" values as defined by the DB. However, some fields behave differently for band-filled data, as indicated by "BF" in the descriptions below. The descriptions below contain the following information: 1. "Name" contains the names of the DB fields or table columns. Note that they are all in lower case, because the DB doesn't distinguish between upper and lower case names. If there is a number in parentheses after the name, please refer to the numbered notes at the end of the descriptions for more information. Many fields are repeated 3 times, once for each band, but are found only once in the description below; these fields contain "" in the name, where "b" is understood to mean "j", "h", and "k". NOTE: The "cntr" column MUST be the first column in each table. 2. "Description" contains short descriptions of the field contents. 3. "Units" contains the units of the values in the fields. 4. "DBType" contains the DB data storage types for the fields. Note that some data types are further defined by values in parentheses following the type name. Also, these types are NOT cast in stone and could change, especially for the position fields. 5. "Null" indicates (y/n) whether the DB fields accept NULL values. 6. "Idx" contains a code indicating whether fields are indexed and what type of indexes they have. If the code is "0", the field is not indexed. If it is "1", the field has a simple index. If there is a "u" after the digit(s), the index is a "unique" one. If the code has a 2-digit number, the first digit indicates to which composite index the field belongs, and the second digit indicates the ordering of the fields within the composite index. If the code has a 3-digit number, the field will have both a simple and composite index. 7. "Fmt" contains a C-like description of the best formats for displaying the field contents, *excluding* a leading space for field separation. 8. "Tbl" contains the (sub-)table ID to which the fields belong. NOTE: The "cntr" field will be the first field in each sub-table, and is used as a join index. The 1st sub-table ("01") is the "main" sub-table, and must contain one entry per table cntr number; any other sub-table will not contain an entry for a cntr number if its fields would all be NULL. 9. "Min", "Sho", and "Std" indicate (y/n) whether the DB fields are found in the "mini", "short", and "standard" table output views. NOTE: A line beginning with "-------" can only be used herein to delineate the section of field/data dictionary lines seen below. Name Description Units DBType Null Idx Fmt Tbl Min Sho Std ---------------------------------------------------------------------------------------------------------------------------------------------- cntr entry counter (key) number (unique within table) - integer n 1 9d 01 n n n ra right ascension (J2000 decimal deg) deg decimal(9,6) n 0 10.6f 01 y y y dec declination (J2000 decimal deg) deg decimal(8,6) n 1 10.6f 01 y y y err_maj major axis of position error ellipse arcsec decimal(3,2) y 0 4.2f 01 n y y err_min minor axis of position error ellipse arcsec decimal(3,2) y 0 4.2f 01 n y y err_ang position angle of error ellipse major axis (E of N) deg smallint y 0 3hd 01 n y y designation (12) source designation formed from sexigesimal coordinates - char(14) n 0 15s 01 n y y j_m (1) J selected "default" magnitude or 95% confidence upper limit mag decimal(5,3) y 1 6.3f 01 y y y j_msig (2) J "default" mag uncertainty mag decimal(4,3) y 0 5.3f 01 y y y j_msigcom (14) J "total" mag uncertainty mag decimal(4,3) y 0 5.3f 01 n n y j_snr (15) J "scan" signal-to-noise ratio - decimal(8,2) y 0 9.2f 01 n n y h_m (1) H selected "default" magnitude or 95% confidence upper limit mag decimal(5,3) y 1 6.3f 01 y y y h_msig (2) H "default" mag uncertainty mag decimal(4,3) y 0 5.3f 01 y y y h_msigcom (14) H "total" mag uncertainty mag decimal(4,3) y 0 5.3f 01 n n y h_snr (15) H "scan" signal-to-noise ratio - decimal(8,2) y 0 9.2f 01 n n y k_m (1) K selected "default" magnitude or 95% confidence upper limit mag decimal(5,3) y 1 6.3f 01 y y y k_msig (2) K "default" mag uncertainty mag decimal(4,3) y 0 5.3f 01 y y y k_msigcom (14) K "total" mag uncertainty mag decimal(4,3) y 0 5.3f 01 n n y k_snr (15) K "scan" signal-to-noise ratio - decimal(8,2) y 0 9.2f 01 n n y rd_flg (3) source of JHK "default" mags (AKA "read flag") - char(3) n 0 3s 01 y y y bl_flg (7) indicates # JHK components fit to source (each digit=0|1|2) - char(3) n 0 3s 01 n y y cc_flg (5) indicates artifact contamination and/or confusion - char(3) n 0 3s 01 y y y extd_flg (11) indicates src associated with or contaminated by an ext. src - smallint y 0 1hd 01 y y y mp_flg (13) source is positionally associated with an asteroid or comet - smallint n 0 1hd 01 y y y id_opt (9) associated optical source catalog ID (closest match) - char(1) y 0 1s 01 n y y b_m_opt catalog blue mag of associated optical source mag decimal(4,2) y 0 5.2f 01 y y y r_m_opt catalog red mag of associated optical source mag decimal(4,2) y 0 5.2f 01 y y y dist_opt distance in arcsec relative to associated optical source arcsec decimal(4,2) y 0 5.2f 01 n y y phi_opt position angle relative to optical source (E of N) deg smallint y 0 3hd 01 n y y nopt_mchs number of optical sources within 5 arcsec of 2MASS src - smallint y 0 2hd 01 n y y date observation date - date y 21 yymmdd 01 n n y hemis hemisphere (N/S) of observation - char(1) y 23 1s 01 n n n scan scan number (unique within date) - smallint y 122 3hd 01 n n n id source ID number (unique within scan) - integer y 0 6d 01 n n n glon galactic longitude (decimal deg) deg decimal(9,6) n 0 10.6f 01 n n y glat galactic latitude (decimal deg) deg decimal(9,6) n 1 10.6f 01 n n y _psfchi band reduced chi-squared value of fit - decimal(5,2) y 0 6.2f 01 n n y j_m_stdap (4) J standard aperture magnitude or BF aperture-photometry mag mag decimal(5,3) y 0 6.3f 01 n n y j_msig_stdap J standard ap. mag/BF ap.-photometry mag uncertainty mag decimal(4,3) y 0 5.3f 01 n n y h_m_stdap (4) H standard aperture magnitude or BF aperture-photometry mag mag decimal(5,3) y 0 6.3f 01 n n y h_msig_stdap H standard ap. mag/BF ap.-photometry mag uncertainty mag decimal(4,3) y 0 5.3f 01 n n y k_m_stdap (4) K standard aperture magnitude or BF aperture-photometry mag mag decimal(5,3) y 0 6.3f 01 n n y k_msig_stdap K standard ap. mag/BF ap.-photometry mag uncertainty mag decimal(4,3) y 0 5.3f 01 n n y ndet_flg (8) number of >3-sig. ap. mag measurements, # possible (jjhhkk) - char(6) y 0 6s 01 n n y j_h (10) default J-H mag color mag decimal(5,3) y 1 7.3f 01 n n y h_k (10) default H-K mag color mag decimal(5,3) y 1 7.3f 01 n n y j_k (10) default J-K mag color mag decimal(5,3) y 1 7.3f 01 n n y ext_key (6) key (cntr value) to matching extended source data record - integer y 1 7d 01 n n n x unit sphere x value - decimal(17,16) n 0 19.16f 01 n n n y unit sphere y value - decimal(17,16) n 0 19.16f 01 n n n z unit sphere z value - decimal(17,16) n 0 19.16f 01 n n n scan_key key to scan data record in the scan data table - integer n 1 6d 01 n n n spt_ind spatial (x,y,z) index key - integer n 1 9d 01 n n n clr_ind color index key - integer y 0 9d 01 n n n ---------------------------------------------------------------------------------------------------------------------------------------------- total # columns = 54 ---------------------------------------------------------------------------------------------------------------------------------------------- NOTES: (1) This is the selected "default" magnitude for each band. For most srcs, the [jhk]_m values are the PSF fit mags for each band (rd_flg=2). Or, if the source has a null PSF mag but a valid standard aperture mag in a band, the [jhk]_m value for that band is the std. ap. mag (rd_flg=4). However, if a src is matched to a R1 src in a band and is saturated in R2-R1 in that band, the [jhk]_m value for that band is the R1 aperture mag (rd_flg=1 or 3). Finally, if a src is band-filled in a band, the value of [jhk]_m for that band is the band-fill 95%-confidence upper limit mag (rd_flg=0). This value is computed as follows:     Lim95 = integrated flux + (2 * noise)
where the noise in this case means the "local noise", computed as follows (using the DAOPHOT algorithm):
    noise = sqrt(error1 + error2 + error3)
where
    error1 = variance in the local sky
          = npix * skyvar
    npix = number of pixels in the aperture
    skyvar = the variance of the sky brightness
    error2 = photon noise
          = int. flux * Gain
    error3 = (skyvar/nsky) * (npix ** 2)
    nsky = number pixels in sky annulus
    (skyvar/nsky) = square of the standard error of the mean sky brightness
For the case in which the integrated flux is negative, the upper limit is
    Lim95 = 2 * noise
where
    noise = sqrt(error1 + error3)
------------------------- (2) The mag sigma values corresponding to the selected "default" magnitude for each band are put in the [jhk]_msig fields. For non-detections (band-fills), the mag sigmas are 9.999. ------------------------- (3) The read flag indicates the source of J,H,K "default" magnitudes as a 3-digit integer, where the 1st digit corresponds to the J band, the 2nd to the H band, and the 3rd to the Ks band. The values are as follows:
0: source is not detected in this band (is band-filled)
1: default mag is R1 aperture
2: default mag is R2-R1 profile-fit
3: default mag is R1 but source is saturated in R1 and its mag is a highly uncertain estimate
4: default mag is R2-R1 standard aperture mag
8: Source position information derived from the Positions and Proper Motions Star Catalogue (Roser and Bastian, 1991), and brightness information estimated from the Catalog of Infrared Observations (Gezari, D. Y., Schmitz, M., and Mead, J. M., NASA Publication 1196), not from 2MASS observations. This usually applies to very bright stars that are heavily saturated in even the 51ms R1 exposures.
------------------------- (4) If a src is not detected in a band (band-filled), this field in that band contains the band-filled aperture-photometry mag. It is calculated by measuring the brightness within an 8" diameter aperture at the position of the source on the Atlas Image.
    BFMag = ZERO_CAL - 2.5 log10(flux)
where ZERO_CAL is the zero calibration magnitude. Note that this field may have to represent a negative flux; in such a case, the value is
    BFMag = 99.0 - [ZERO_CAL - 2.5 log10(|flux|)]
This encoding requires fluxes close to zero to be clipped. The clipping distance is set to 0.01 DN above zero for positive fluxes and below zero for negative fluxes. For example, the positive flux 0.0005 DN would be clipped at 0.01 DN and encoded as
    BFMag = ZERO_CAL - 2.5 log10(0.01)
         = 24.93 (for ZERO_CAL = 19.93)
For a negative flux of -0.0005 DN, the clipping would yield -0.01 DN, and the encoding would be
    BFMag = 99.0 - [ZERO_CAL - 2.5 log10(0.01)]
         = 74.07 (for ZERO_CAL = 19.93)
BFMags near 50 cannot occur, so 50 marks the boundary between positive and negative flux encoding. ------------------------- (5) The contamination/confusion flag indicates whether the source's photometry and position may be affected by artifacts of nearby bright stars or by confusion with other nearby sources. The flag consists of a 3 character string, where the 1st character corresponds to the J band, the 2nd to the H band, and the 3rd to the Ks band. Sources are tested for contamination and/or confusion in the order given below, and once a flag is applied to the source, testing is stopped in that band. The flag values indicate the source may be affected by:
P: a nearby persistence artifact
D: a nearby diffraction spike
S: a horizontal "stripe" artifact (due to a bright star) at delta_y = 0, 256, -256 arcsec
R: a nearby bright star reflection artifact
C: confusion with another nearby source
B: confusion in bandmerging
0: default value -- not contaminated or not detected in the band
------------------------- (6) If the source is identically associated with an object in the extended source catalog (e.g. the nucleus of a galaxy), the ext_key field is set to the key ("cntr" value) of the record in the extended source catalog containing the extended source data. The extended source data will also have the same date, hemisphere, scan, id values. ------------------------- (7) The "blend" flag indicates how many point source components were fit to each band's source during the profile fitting process. It is a 3-digit integer, where each digit can be 0, 1, or 2, and the 1st digit corresponds to the J band, the 2nd to the H band, and the 3rd to the Ks band. ------------------------- (8) This flag consists of 6 single-digit numbers, two digits per band in the order JJHHKK. The 1st digit for each band indicates the number of frames with >3-sigma aperture mag measurements, and the 2nd digit indicates the number of frames in which aperture measurements were possible. (This flag is AKA the N-out-of-M statistic). ------------------------- (9) The catalog ID and other association parameters are given for the closest optical match found within 5 arcsec. The ID consists of a single-letter abbreviation for the catalog (e.g., 'T' for Tycho, 'U' for USNO-A). ------------------------- (10) For bands with source detections and non-negative fluxes, the [jhk]_m default mag values are used to calculate the mag colors J-H,...R-K,...etc. If one or both of the bands used in the calculation is not-detected, no color is calculated. ------------------------- (11) The "extended" flag is set to 0 if the point source is not associated with an extended source, 1 if it is identically associated with an object in the extended source catalog (e.g. the nucleus of a galaxy), or 2 if it is simply contaminated by an extended source (e.g. a star superimposed on the disk of a galaxy). ------------------------- (12) This is the object sequence designation, or object "name" as specified by the IAU recommendations on source nomenclature. It is derived from the J2000 sexigesimal coordinates of the source and has the form HHMMSSS+/-DDMMSS, where HH are the hours of right ascension, MM the RA minutes and SSS are the deci-seconds of RA. DD are the degrees in declination, MM are DEC minutes and SS the declination seconds. Note that both the RA deci-seconds of time and DEC seconds of arc are truncated rather than rounded, per the IAU recommendation. ------------------------- (13) This object is positionally associated with the location of a known minor planet or comet at the time of the 2MASS observation. See the table of known asteroid and comet detections for this data release for more information. ------------------------- (14) The "combined" uncertainty in the quoted magnitude for each band that provides an estimate of all random errors that contribute to the photometric uncertainty. This uncertainty is the quadratic combination of the extraction uncertainites ([jhk]_msig), and the photometric zero point offset uncertainties from the night during which the source was observed ([jhk]_zperr from the "Scan Data" table), and the residual flat-fielding errors (estimated to be 0.005 mags for all bands). For R1 sources, the quadratic sum includes the RMS uncertainty in the normalization of the R1 photometry to the R2-R1 photometry ([jhk]_r1normrms from the "Scan Data" table). ------------------------- (15) The "scan" signal-to-noise ratio is the ratio of the flux density for a source in each band to the mode point source noise in each band. For non-detections, the scan signal-to-noise ratio is null. ---------------------------------------------------------------------------------------------------------------------------------------------- Possible NULL fields -------------------- For information on possible NULL fields, see the pt_src SIS DBM01.