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II/281          2MASS 6X Point Source Working Database / Catalog   (Cutri+ 2006)

The 2MASS 6X Point Source Working Database / Catalog Cutri R.M., Skrutskie M.F., Van Dyk S., Beichman C.A., Carpenter J.M., Chester T., Cambresy L., Evans T., Fowler J., Gizis J., Howard E., Huchra J., Jarrett T., Kopan E.L., Kirkpatrick J.D., Light R.M, Marsh K.A., McCallon H., Schneider S., Stiening R., Sykes M., Weinberg M., Wheaton W.A., Wheelock S., Zacharias N. <IPAC, Caltech (2006)> =2012yCat.2281....0C
ADC_Keywords: Infrared sources ; Photometry, infrared ; Surveys Description: A special set of observations that utilized exposure times six times longer than the main 2MASS survey measurements were conducted in the final year of 2MASS observatory operations. The 2MASS "6x" observations achieved sensitivities ∼1 mag deeper than the main 2MASS survey, and covered approximately 590 deg2 of sky in 30 discrete regions. The 2MASS 6x Point Source Working Databases (6x-PSWDB and 6x-XSWDB) contain all detections extracted from the raw 6x imaging data during pipeline data reduction. The 6x WDB entries include reliable detections of astrophysical sources, as well as spurious detections of noise excursions, image artifacts and transient events such as meteor trails, cosmic rays and hot pixels. In addition, the WDBs may contain multiple, independent detections of objects scanned more than once during the 6x observations. The 2MASS 6x Point Source Catalogs (6x-PSC and 6x-XSC) is a subset of extractions in the 6x-PSWDB that have been identified to be high reliability source detections, with only one measurement of sources detected multiple times for uniformity. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file 2mass6x.sam 261 500 Sample of 2MASS-6X
See also: http://http://www.ipac.caltech.edu/2mass/releases/allsky/doc/explsup.html : 2MASS documentation II/246 : The Two Micron All-Sky Survey: Point sources (Cutri+ 2003) VII/233 : The Two Micron All-Sky Survey: Extended sources (Cutri+ 2003) Byte-by-byte Description of file: 2mass6x.sam
Bytes Format Units Label Explanations
1- 16 A16 --- 2MASS Source designation 18- 27 F10.6 deg RAdeg Right ascension (J2000) 29- 38 F10.6 deg DEdeg Declination (J2000) 40- 44 F5.3 arcsec eeMaj Semi-major axis of the error ellipse 46- 50 F5.3 arcsec eeMin Semi-minor axis of the error ellipse 52- 58 F7.3 deg eerPA Position angle of the error ellipse 60- 65 F6.3 mag Jmag ? 2MASS J magnitude (1.25um) 67- 72 F6.3 mag Hmag ? 2MASS H magnitude (1.65um) 74- 79 F6.3 mag Kmag ? 2MASS Ks magnitude (2.17um) 81- 85 F5.3 mag e_Jmag ? 1-σ total error on Jmag 87- 91 F5.3 mag e_Hmag ? 1-σ total error on Hmag 93- 97 F5.3 mag e_Kmag ? 1-σ total error on Ksmag 99-101 A3 --- Qflg [ABCDEFUXZ] JHK Photometric quality flag (1) 103-105 I3 --- Rflg JHK Read flag (rd_flg) (2) 107 I1 --- Xflg [0/2] Extended source contamination flag (3) 109-120 F12.4 d JD Julian Date of observation 122-129 I8 --- gcntr ID of the record Merged Point Source Information table 131-140 F10.6 deg GLON Galactic longitude 142-151 F10.6 deg GLAT Galactic latitude 153-157 F5.3 mag Jsig ? 1-σ default error on Jmag 159-163 F5.3 mag Hsig ? 1-σ default error on Hmag 165-169 F5.3 mag Ksig ? 1-σ default error on Ksmag 171-180 F10.2 --- Jsnr ? J Band Signal/Noise 182-191 F10.2 --- Hsnr ? H Band Signal/Noise 193-202 F10.2 --- Ksnr ? Ks Band Signal/Noise 204-216 A13 --- Opt ? Optical source designation 218-221 F4.2 arcsec Dopt ? Distance between 2MASS and optical source 223-228 I6 deg PAopt ?=-32768 Position Angle between 2MASS and optical source 230-233 F4.1 mag Bmag ? B magnitude 235-238 F4.1 mag Rmag ? V or R magnitude 240 I1 --- Nopt [0/6] Number of optical sources within 5arcsec 242-244 I3 --- Bflg JHK Blend flag (bl_flg) (4) 246-248 A3 --- Cflg JHK Contamination and confusion flag (cc_flg) (5) 250 I1 --- Pflg Minor Planet flag (mp_flg) (6) 252-257 I6 --- Ndet Frame detection statistics (7) 259 I1 --- cat Catalog flag (1:catalog, 0:archive) 261 A1 --- rel [ABCDEF] Reliability flag (8)
Note (1): Photometric quality flag (ph_qual). Three character flag, one character per band [JHK], that provides a summary of the net quality of the default photometry in each band, as derived from the Read Flag (rd_flg), measurement uncertainties ([jhk]_msig), scan signal-to-noise ratios ([jhk]_snr), frame-detection statistics (ndet), and profile-fit reduced chi-squared values ([jhk]_psfchi). The value for ph_qual is set for a band according to the precedence of the table below. For example, a source that is tested and meets the conditions for category "X" is not tested for subsequent qualities. X = There is a detection at this location, but no valid brightness estimate can be extracted using any algorithm. rd_flg="9" and default magnitude is null. U = Upper limit on magnitude. Source is not detected in this band (rd_flg="0"), or it is detected, but not resolved in a consistent fashion with other bands (rd_flg="6"). A value of ph_qual="U" does not necessarily mean that there is no flux detected in this band at the location. Whether or not flux has been detected can be determined from the value of rd_flg. When rd_flg="0", no flux has been detected. When rd_flg="6", flux has been detected at the location where the images were not deblended consistently in all three bands (JHK). Z = The detection in this band is positionally associated with the predicted location of an image artifact. The cc_flg value in this band will be C,D,G or P. F = This category includes rd_flg="1" or rd_flg="3" sources where a reliable estimate of the photometric error, [jhk]_msig, could not be determined. The uncertainties reported for these sources in [jhk]_msig and [jhk]_msigcom are flags and have numeric values >8.0. E = This category includes detections where the goodness-of-fit quality of the profile-fit photometry was very poor (rd_flg="2" and [jhk]psf_chi>10.0), or detections where psf fit photometry did not converge and an aperture magnitude is reported (rd_flg="4"), or detections where the number of frames was too small in relation to the number of frames in which a detection was geometrically possible (rd_flg="1" or rd_flg="2"). A = Detections in any brightness regime where valid measurements were made (rd_flg="1","2" or "3") with [jhk]_snr>10 AND [jhk]_msig<0.10857. B = Detections in any brightness regime where valid measurements were made (rd_flg="1","2" or "3") with [jhk]_snr>7 AND [jhk]_msig<0.15510. C = Detections in any brightness regime where valid measurements were made (rd_flg="1","2" or "3") with [jhk]_snr>5 AND [jhk]_msig<0.21714. D = Detections in any brightness regime where valid measurements were made (rd_flg="1","2" or "3") with no [jhk]_snr or [jhk]_msig requirement. Note (2): Read flag. Three character flag, one character per band [JHK], that indicates the origin of the default magnitudes and uncertainties in each band ([JHK]mag, [JHK]sig). Values of "1", "2" or "3" generally indicate the best quality detections, photometry and astrometry. Values of "0", "4", "6" and "9" in a band indicate either non-detections, or generally poor quality photometry and positions. The definitions of the Rflg (rd_flg) values are: 0 = Source is not detected in this band. The default magnitude is the 95% confidence upper limit derived from a 4" radius aperture measurement taken at the position of the source on the 6x Atlas Image. The sky background is estimated in an annular region with inner radius of 14" and outer radius of 20". 1 = The default magnitude is derived from aperture photometry measurements on the 51 ms "Read_1" exposures. The aperture radius is 4", with the sky background measured in an annulus with an inner radius of 14" and an outer radius of 20". Used for sources that saturate one or more of the 7.8s "Read_2" exposures, but are not saturated on at least one of the 51 ms "Read_1" frames. 2 = The default magnitude is derived from a profile-fitting measurement made on the 7.8 sec "Read_2" exposures. The profile-fit magnitudes are normalized to curve-of-growth-corrected aperture magnitudes. This is the most common type in the 6x-PSWDB/PSC, and is used for sources that have no saturated pixels in any of the 7.8 sec exposures. 3 = The default magnitude is derived from a 1-d radial profile fitting measurement made on the 51 ms "Read_1" exposures. Used for very bright sources that saturate all of the 51 ms "Read 1" exposures. 4 = The default magnitude is derived from curve-of-growth-corrected 4" radius aperture photometry measurements on the 7.8 s "Read_2" exposures. This is used for sources that are not saturated in any of the Read_2 frames, but where the profile-fitting measurements fail to converge to a solution. These magnitudes are the same as the standard aperture magnitudes (jmstdap, hmstdap, kmstdap), but when they are the default magnitudes, it generally implies that they are low quality measurements. 6 = The default magnitude is the 95% confidence upper limit derived from a 4" radius aperture measurement taken at the position of the source on the 6x Atlas Image. The sky background is estimated in an annular region with inner radius of 14" and outer radius of 20". This is used for pairs of sources which are detected and resolved in another band, but are detected and not resolved in this band. This differs from a rd_flg="0" because in this case there is a detection of the source in this band, but it is not consistently resolved across all bands. 9 = The default magnitude is the 95% confidence upper limit derived from a 4" radius aperture measurement taken at the position of the source on the 6x Atlas Image. The sky background is estimated in an annular region with inner radius of 14" and outer radius of 20". This is used for sources that were nominally detected in this band, but which could not have a useful brightness measurement from either profile fitting or aperture photometry. This often occurs in highly confused regions, or very near Tile edges where a significant fraction of the measurement aperture of sky annulus falls off the focal plane. Note (3): Xflg Extended source "contamination" flag (gal_contam). 0 = Source does not fall within the elliptical profile of an extended source with semi-major axis >10'', or it is not identified exactly with an XSC source with semi-major axis >10''. 1 = Source is resolved by 2MASS, and is equivalent to a source in the XSWDB that has a semi-major axis >10'' in size (usually the nuclei of galaxies). The 6x-PSWDB/PSC Xflg values correctly flag all point sources that are found to be resolved relative to a single point-spread-function, regardless of extended source size. 2 = Source falls within the elliptical boundary of an XSC source that has a semi-major axis >10'' in size. Sources so indicated are often foreground stars superimposed on background galaxies, or sometimes extractions of pieces of the galaxy or nebula. The point source photometry for these sources is probably contaminated by the surrounding structured extended emission. Point sources can still be superimposed on extended sources and remain unflagged if the XSC source shape is not well-described by an ellipse. Note (4): Blend flag (bl_flg). Three character flag, one character per band [JHK], that indicates the number of components that were fit simultaneously when estimating the brightness of a source: 0 = Source is not detected, or is inconsistently deblended in that band. 1 = One component was fit to the source in R2 profile-fitting photometry (rd_flg="2"), or default magnitudes are from aperture photometry (rd_flg="1" or "4") or saturated star 1-d radial profile-fitting (rd_flg="3"). >1 = More than one component was fit simultaneously during R2 profile-fit photometry, where the value of the field is the number of components simultaneously fit. The maximum number of components is 7 in any band for the 6x-PSWDB/PSC, so this bl_flg is always a three character flag. Multi-component fitting occurs only for profile-fitting, and only when more than one detection is found within ∼5". Single detections that are not well-fit by a single PSF are not split. Note (5): Contamination and confusion flag. Three character flag, one character per band [JHK], that indicates that the extraction is associated with the predicted position of an image artifact, or that the photometry and/or position measurements of a source may be contaminated or biased due to proximity to an image artifact or nearby source of equal or greater brightness. The cc_flg in each band is set in hierarchical order according to the following table, in the event a source is affected by more than one artifact or condition: P = Persistence artifact. Extraction is likely a spurious detection of a latent image left by a nearby bright star. G = Dichroic glint artifact. Extraction is likely a spurious detection of a dichroic glint produced by a nearby bright star. C = Confusion artifact. Extraction is likely a spurious detection in the wings of a nearby bright star. D = Diffraction spike artifact. Extraction is likely a spurious detection on a diffraction spike from a nearby star. p = Persistence. Source may be contaminated by a latent image left by a nearby bright star. c = Photometric Confusion. Source photometry is biased by a nearby star that has contaminated the background estimation. This is very common in high source density regions. d = Diffraction spike confusion. Source may be contaminated by a diffraction spike from a nearby star. s = Electronic stripe. Source measurement may be contaminated by a stripe from a nearby bright star. b = Bandmerge confusion. In the process of merging detections in the different bands for this source, there was more than one possible match between the different band components. This occurs in regions of very high source density, or when multiple sources were split in one band but not another. 0 = Source is unaffected by known artifacts, or is not detected in the band. Non-zero values the cc_flg in any band is an indicator that the extraction may be a spurious detection of an image artifact, or that measurements of that source may be contaminated. Note (6): Minor Planet Flag. Indicates if this source is associated with the predicted position of a known minor planet, comet, planet or planetary satellite. This association does not guarantee that the 6x-PSWDB/PSC source is a detection of the solar system object. 0 = Source is not associated with a known solar system object 1 = Source is associated with the predicted position of a known solar system object. The name and orbital data for the associated objects are given in the Known Asteroid Detection List, Known Comet Detection List, and Planet and Planetary Satellite Detection List. The associated 6x-PSWDB/PSC source is cross-referenced in those Lists via the value of pts_key. Note (7): Frame detection statistics. A six-character flag, two characters per band [JJHHKK], that indicates the number frames on which a source was detected, N, and the number of frames on which the source could have been measured, M. The first digit in the pair for each band, N, gives the number of frames on which there were >3σ aperture photometry detections of the source. The second digit for each band, M, gives the number of frames on which aperture measurements were possible. Normally, M=6, (occasionally M=7 because the scanning step size was slightly less than 1/6 of the frame size). M can be <6 if frames are "lost" because: a) there were masked pixels within the source aperture due to cosmic ray detections, noisy pixels, meteor trails, etc, or b) there were saturated pixels within the source aperture. Values of M<6 are not uncommon, but do indicate an effective loss of coverage and sensitivity for a source. The values of N and M for a band always pertain to the aperture photometry on the 51 ms "Read_1" exposures if rd_flg="1", and to the aperture photometry on the 7.8 s "Read_2" exposures if rd_flg="2" or "4". Sources that are saturated on all of the Read_1 frames (rd_flg="3") have N=0 because no aperture photometry was possible. Sources with signal-to-noise ratios >8-9 should be detected on all available frames. Values of N < M for such sources are an indication of possible loss of measurement integrity. Values of N < M, or even N=0, are normal for fainter sources because they are too faint on individual frames to yield a >3σ detection. Note (8): Reliability flag. Single character flag that is related to the probability that the extraction is a valid detection of a near infrared source on the sky at the time of the observation. A = P>90% B = 80%<P<90% C = 70%<P<80% D = 50%<P<70% E = 20%<P<50% F = P<20% This flag does not provide information about the quality of the position or flux measurement. For that, users should refer to the ph_qual, rd_flg, cc_flg and positional and photometric uncertainties.

(End) Laurent Cambresy [CDS] 27-Feb-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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