| Column # | Column Name | Description | Units | Data Type |
|---|---|---|---|---|
| 1 | cntr | entry counter (key) number (unique within table) | --- | integer |
| 2 | ra | right ascension (J2000 decimal deg) | deg | decimal(9,6) |
| 3 | dec | declination (J2000 decimal deg) | deg | decimal(8,6) |
| 4 | err_maj | major axis of position error ellipse | arcsec | decimal(3,2) |
| 5 | err_min | minor axis of position error ellipse | arcsec | decimal(3,2) |
| 6 | err_ang | position angle of error ellipse major axis (E of N) | deg | smallint |
| 7 | j_m | J selected "default" magnitude or 95% confidence upper limit | mag | decimal(5,3) |
| Notes for j_m: 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) | ||||
| 8 | j_msig | J "default" mag uncertainty | mag | decimal(4,3) |
| Notes for j_msig: 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. | ||||
| 9 | h_m | H selected "default" magnitude or 95% confidence upper limit | mag | decimal(5,3) |
| Notes for h_m: 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) | ||||
| 10 | h_msig | H "default" mag uncertainty | mag | decimal(4,3) |
| Notes for h_msig: 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. | ||||
| 11 | k_m | K selected "default" magnitude or 95% confidence upper limit | mag | decimal(5,3) |
| Notes for k_m: 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) | ||||
| 12 | k_msig | K "default" mag uncertainty | mag | decimal(4,3) |
| Notes for k_msig: 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. | ||||
| 13 | rd_flg | source of JHK "default" mags (AKA "read flag") | --- | char(3) |
| Notes for rd_flg: 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 51-ms R1 exposures. | ||||
| 14 | bl_flg | indicates # JHK components fit to source (each digit=0|1|2) | --- | char(3) |
| Notes for bl_flg: 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. | ||||
| 15 | cc_flg | indicates artifact contamination and/or confusion | --- | char(3) |
| Notes for cc_flg: 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 | ||||
| 16 | extd_flg | indicates src associated with or contaminated by an ext. src | --- | smallint |
| Notes for extd_flg: 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). | ||||
| 17 | id_opt | associated optical source catalog ID (closest match) | --- | char(13) |
| Notes for id_opt: 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) followed immediately by the ID of the object within that catalog, with no embedded blanks. | ||||
| 18 | b_m_opt | catalog blue mag of associated optical source | mag | decimal(4,2) |
| 19 | r_m_opt | catalog red mag of associated optical source | mag | decimal(4,2) |
| 20 | dist_opt | distance in arcsec relative to associated optical source | arcsec | decimal(4,2) |
| 21 | phi_opt | position angle relative to optical source (E of N) | deg | smallint |
| 22 | nopt_mchs | number of optical sources within 5 arcsec of 2MASS src | --- | smallint |
| 23 | date | observation date | --- | date |
| 24 | hemis | hemisphere (N/S) of observation | --- | char(1) |
| 25 | scan | scan number (unique within date) | --- | smallint |
| 26 | id | source ID number (unique within scan) | --- | integer |
| 27 | glon | galactic longitude (decimal deg) | deg | decimal(9,6) |
| 28 | glat | galactic latitude (decimal deg) | deg | decimal(9,6) |
| 29 | x_scan | x (cross-scan) position (U-Scan coordinates) | arcsec | decimal(5,2) |
| 30 | y_scan | y (in-scan) position (U-Scan coordinates) | arcsec | decimal(7,2) |
| 31 | j_psfchi | J band reduced chi-squared value of fit | --- | decimal(5,2) |
| 32 | h_psfchi | H band reduced chi-squared value of fit | --- | decimal(5,2) |
| 33 | k_psfchi | K band reduced chi-squared value of fit | --- | decimal(5,2) |
| 34 | j_m_stdap | J standard aperture magnitude or BF aperture-photometry mag | mag | decimal(5,3) |
| Notes for j_m_stdap: 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. | ||||
| 35 | j_msig_stdap | J standard ap. mag/BF ap.-photometry mag uncertainty | mag | decimal(4,3) |
| 36 | h_m_stdap | H standard aperture magnitude or BF aperture-photometry mag | mag | decimal(5,3) |
| Notes for h_m_stdap: 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. | ||||
| 37 | h_msig_stdap | H standard ap. mag/BF ap.-photometry mag uncertainty | mag | decimal(4,3) |
| 38 | k_m_stdap | K standard aperture magnitude or BF aperture-photometry mag | mag | decimal(5,3) |
| Notes for k_m_stdap: 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. | ||||
| 39 | k_msig_stdap | K standard ap. mag/BF ap.-photometry mag uncertainty | mag | decimal(4,3) |
| 40 | ndet_flg | number of >3-sig. ap. mag measurements, # possible (jjhhkk) | --- | char(6) |
| Notes for ndet_flg: 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). | ||||
| 41 | ext_key | key (cntr value) to matching extended source data record | --- | integer |
| Notes for ext_key: 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. | ||||