VI. Analysis of the 2MASS Second Incremental Release Catalogs
6. PSC Reference Field Characteristics
a. Introduction
We have generated a number of diagnostic plots to characterize the Point Source Catalog behavior over a variety of galactic and equatorial positions. At each position, a circular (in galactic coordinates) Reference Field with 1° radius has been defined, and all PSC entires within the regions have been extracted. These Reference Fields provide a more "microscopic" spot-checking of the catalog to complement the global characterizations of the PSC carried out by M. Weinberg in Section VI.6a and J. Carpenter in Section VI.2b.
The first 11 Reference Fields sample northern data, and the second 11 Fields probe the south.
These reference fields are also designed to be used as target regions for other investigations. Please see M. Egan's comparison of the source counts with SKY model predictions in Section VI.7a for these fields.
b. Field Selection
The Reference Fields were selected using two criteria:
- The field centers were chosen to sample the catalog at regular intervals in both galactic coordinates, to illustrate the effects of source density, and equatorial coordinates to illustrate any possible telescope position dependent effects.
- Fields were selected to have contiguous coverage over their 2° diameters. This was verified by using the Survey Visualizer interface to allow one to "zoom-in" on the Release fields.
- Distribution of points in galactic coordinate
- d(log N)/dM - Differential Source Counts in Srcs/Deg2 (normalized to the 3.14° field areas)
- N(< M) - Surface Density in Srcs/Deg2 of Sources brighter than magnitude M
- Magnitude Sigma vs. Magnitude - Photometric measurement error
- Chi-Squared values vs. Magnitude - PSF goodness-of-fit. Point Sources associated with extended sources (extd_flg>0) are denoted with a black "x")
- Chi-Squared values vs. Magnitude Sigmas. Point Sources associated with extended sources (extd_flg>0) are denoted with a black "x")
- J-H vs. H-Ks Color-Color diagram - Green line denotes Bessell & Brett dwarf isochrone, Red line denotes giant isochrone. Source with Ks SNR>30 denoted with yellow points, Ks SNR>20 with blue points, and SNR < 20 with black points.
- J-Ks vs. B-Ks Color-Color diagram. Source with Ks SNR>20 denoted with blue points, and SNR < 20 with black points.
- Sigma(J) vs. Sigma(H) vs. Sigma(Ks)
- Chi-Squared(J) vs. Chi-Squared(H) vs. Chi-Squared(Ks)
No a priori knowledge of contents of a field were used in field selection.
The table below lists the definitions of the current set of Reference Fields, along with the total number of point sources in each field.
|N | RA | Dec0 | glon0 | glat0 | radius | nsrcs | | | c | c | d | d | d | i | 1 12h50m00s +15d00m00s 301.28 +77.87 3600.0 3701 2 10h42m00s +21d00m00s 217.58 +59.91 3600.0 4406 3 09h16m00s +21d00m00s 207.79 +40.80 3600.0 6193 4 08h17m00s +21d00m00s 202.27 +28.80 3600.0 9403 5 06h56m00s +27d00m00s 188.97 +12.87 3600.0 27134 6 06h20m00s +21d00m00s 190.75 +2.85 3600.0 50724 7 04h45m00s +27d00m00s 175.09 -10.47 3600.0 27333 8 04h35m00s +15d00m00s 182.10 -21.35 3600.0 11520 9 02h21m00s +21d00m00s 149.45 -37.22 3600.0 6209 10 19h30m00s +21d00m00s 55.03 +0.91 3600.0 273545 11 12h55m00s +32d00m00s 114.12 +85.07 3600.0 2972 12 18h45m00s -16d00m00s 17.92 -5.83 3600.0 211253 13 19h35m00s -18d00m00s 21.25 -17.51 3600.0 49670 14 20h25m00s -24d00m00s 19.73 -30.55 3600.0 19348 15 21h50m00s -27d00m00s 22.34 -49.84 3600.0 7636 16 23h10m00s -24d00m00s 35.04 -66.95 3600.0 4800 17 00h50m00s -27d00m00s 35.16 -87.45 3600.0 3721 18 02h30m00s -22d00m00s 205.43 -67.05 3600.0 3686 19 02h50m00s -46d00m00s 259.66 -59.92 3600.0 4382 20 05h10m00s -30d00m00s 232.35 -33.92 3600.0 8118 21 06h15m00s -26d00m00s 233.06 -19.06 3600.0 19941 22 07h50m00s -30d00m00s 245.96 -1.90 3600.0 98542
c. Diagnostic Plots
Plots showing the following relationships for the PSC entries in each field have been generated. Whenever single-band information is shown in a plot panel, J-band sources are denoted by blue points, H-band by green points, and Ks by red points.
d. The Plots
[Last Updated: 2000 Jan 8 by R. Cutri. Modified 2000 Aug 28 by S. Van Dyk.]
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