XSC -- Virgo Galaxy Cluster:
Low Resolution, 50 deg2 Large Mosaic
In order to test the XSC completeness on a much larger scale, we employ a large mosaic with low spatial resolution:
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Pixel size = 3"
Image size = 9300 X 7200 pixels
Field of View = 7.8 X 6 degrees
Displayed image shows the combined J + H + Ks channels.
a. Results
The Virgo mosaic was split into 99 pieces, each 800X800 pixels (approximately 40 arcmin on a side). The database extended sources were marked with blue circles, and the XSC sources with green circles. The sub-images were then visually inspected, concentrating on clearly delineated Virgo galaxies that are not in the XSC (i.e., source not circled in green). These sources (denoted with red circles) represent incompleteness in the XSC. The following table presents the 11X9 grid of sub-images with additional "zoom" images of galaxies missing from the XSC. (things to note: "chaff" in proximity to large and bright galaxies is mostly eliminated from the XSC; artifacts from bright stars; airglow and background gradients; source confusion; faint or compact sources provide little if any information for this experiment)
b. Missing Sources
The following table lists the sources identified from the Virgo mosaic that do not have an XSC counterpart. Table: (ip,jp) == panel number; (x,y) = pixel coordinates; (ra,dec) == equatorial coordinates; (radius) == circular radius in arcsec; (mag, msig) == J mag & rms; (gif) == zoomed image.
Bottom Line: Most of the missing galaxies are low surface brightness, with SNRs well below the Level-1 science requirements. With regard to clearly delineated galaxies (well extended, diameters > 10-20"), the XSC completeness in VIRGO is comfortably satisfied.
| IP | JP | x | y | ra | dec | radius | ba | pa | ib | mag | msig | gif | image |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2 | 1 | 1574.0 | 6789.0 | 189.89700 | 16.09676 | 10.0 | 1.000 | 0.0 | j | 10.602 | 0.017 | gif | virgo_J2.fits |
| 2 | 1 | 1011.0 | 6611.0 | 190.38402 | 15.94341 | 10.0 | 1.000 | 0.0 | j | 15.303 | 0.531 | gif | virgo_J2.fits |
| 5 | 1 | 3271.0 | 6687.0 | 188.42320 | 16.02272 | 10.0 | 1.000 | 0.0 | j | 12.536 | 0.044 | gif | virgo_J2.fits |
| 9 | 1 | 6851.0 | 7020.0 | 185.31224 | 16.29564 | 10.0 | 1.000 | 0.0 | j | 11.401 | 0.021 | gif | virgo_J2.fits |
| 1 | 2 | 765.0 | 5968.0 | 190.58885 | 15.40313 | 10.0 | 1.000 | 0.0 | j | 10.759 | 0.017 | gif | virgo_J2.fits |
| 4 | 2 | 2993.0 | 6186.0 | 188.66069 | 15.60322 | 10.0 | 1.000 | 0.0 | j | 14.414 | 0.235 | gif | virgo_J2.fits |
| 5 | 2 | 3233.0 | 5663.0 | 188.45021 | 15.16779 | 30.0 | 1.000 | 0.0 | j | 10.960 | 0.033 | gif | virgo_J2.fits |
| 5 | 2 | 3233.0 | 5663.0 | 188.45021 | 15.16779 | 30.0 | 1.000 | 0.0 | j | 10.960 | 0.033 | gif | virgo_J2.fits |
| 6 | 2 | 4043.0 | 6335.0 | 187.75063 | 15.73193 | 20.0 | 1.000 | 0.0 | j | 13.771 | 0.261 | gif | virgo_J2.fits |
| 8 | 2 | 6062.0 | 5873.0 | 186.00397 | 15.34307 | 10.0 | 1.000 | 0.0 | j | 11.494 | 0.022 | gif | virgo_J2.fits |
| 11 | 2 | 8577.0 | 6120.0 | 183.82355 | 15.52952 | 10.0 | 1.000 | 0.0 | j | 10.812 | 0.017 | gif | virgo_J2.fits |
| 2 | 3 | 1046.0 | 5122.0 | 190.33504 | 14.70030 | 20.0 | 1.000 | 0.0 | j | 13.029 | 0.132 | gif | virgo_J2.fits |
| 2 | 3 | 1340.0 | 5136.0 | 190.08134 | 14.71495 | 20.0 | 1.000 | 0.0 | j | 13.335 | 0.175 | gif | virgo_J2.fits |
| 3 | 3 | 2365.0 | 5156.0 | 189.19589 | 14.74003 | 10.0 | 1.000 | 0.0 | j | 14.758 | 0.322 | gif | virgo_J2.fits |
| 4 | 3 | 2933.0 | 5435.0 | 188.70737 | 14.97699 | 10.0 | 1.000 | 0.0 | j | 11.185 | 0.019 | gif | virgo_J2.fits |
| 6 | 3 | 4406.0 | 5488.0 | 187.43617 | 15.02460 | 10.0 | 1.000 | 0.0 | j | 14.632 | 0.287 | gif | virgo_J2.fits |
| 7 | 3 | 5551.0 | 5403.0 | 186.44835 | 14.95258 | 10.0 | 1.000 | 0.0 | j | 14.185 | 0.190 | gif | virgo_J2.fits |
| 8 | 3 | 5951.0 | 5550.0 | 186.10144 | 15.07395 | 10.0 | 1.000 | 0.0 | j | 14.456 | 0.244 | gif | virgo_J2.fits |
| 1 | 4 | 669.0 | 4715.0 | 190.65535 | 14.35658 | 30.0 | 1.000 | 0.0 | j | 12.044 | 0.082 | gif | virgo_J2.fits |
| 2 | 4 | 867.0 | 4013.0 | 190.47626 | 13.77326 | 20.0 | 1.000 | 0.0 | j | 13.056 | 0.135 | gif | virgo_J2.fits |
| 3 | 4 | 1871.0 | 4364.0 | 189.61604 | 14.07648 | 10.0 | 1.000 | 0.0 | j | 14.797 | 0.334 | gif | virgo_J2.fits |
| 4 | 4 | 2673.0 | 4238.0 | 188.92514 | 13.97610 | 10.0 | 1.000 | 0.0 | j | 16.289 | 1.317 | gif | virgo_J2.fits |
| 5 | 4 | 3942.0 | 4398.0 | 187.83443 | 14.11453 | 20.0 | 1.000 | 0.0 | j | 13.147 | 0.147 | gif | virgo_J2.fits |
| 7 | 4 | 5117.0 | 4438.0 | 186.82368 | 14.14832 | 10.0 | 1.000 | 0.0 | j | 9.619 | 0.015 | gif | virgo_J2.fits |
| 9 | 4 | 7050.0 | 4786.0 | 185.15776 | 14.43055 | 10.0 | 1.000 | 0.0 | j | 10.427 | 0.016 | gif | virgo_J2.fits |
| 9 | 4 | 6687.0 | 4716.0 | 185.47018 | 14.37450 | 10.0 | 1.000 | 0.0 | j | 11.664 | 0.024 | gif | virgo_J2.fits |
| 10 | 4 | 7519.0 | 4253.0 | 184.75838 | 13.98232 | 20.0 | 1.000 | 0.0 | j | 13.552 | 0.213 | gif | virgo_J2.fits |
| 3 | 5 | 2367.0 | 3381.0 | 189.18237 | 13.25933 | 20.0 | 1.000 | 0.0 | j | 11.469 | 0.035 | gif | virgo_J2.fits |
| 4 | 5 | 2877.0 | 3742.0 | 188.74702 | 13.56346 | 10.0 | 1.000 | 0.0 | j | 12.157 | 0.033 | gif | virgo_J2.fits |
| 4 | 5 | 2434.0 | 3836.0 | 189.12794 | 13.63930 | 10.0 | 1.000 | 0.0 | j | 15.003 | 0.403 | gif | virgo_J2.fits |
| 7 | 5 | 5229.0 | 3739.0 | 186.72859 | 13.56505 | 10.0 | 1.000 | 0.0 | j | 14.515 | 0.258 | gif | virgo_J2.fits |
| 7 | 5 | 5543.0 | 3299.0 | 186.46030 | 13.19734 | 10.0 | 1.000 | 0.0 | j | 14.779 | 0.328 | gif | virgo_J2.fits |
| 8 | 5 | 6194.0 | 3647.0 | 185.90085 | 13.48533 | 10.0 | 1.000 | 0.0 | j | 10.377 | 0.016 | gif | virgo_J2.fits |
| 8 | 5 | 5625.0 | 3335.0 | 186.38992 | 13.22715 | 10.0 | 1.000 | 0.0 | j | 14.781 | 0.329 | gif | virgo_J2.fits |
| 11 | 5 | 8524.0 | 3829.0 | 183.89851 | 13.61878 | 10.0 | 1.000 | 0.0 | j | 14.737 | 0.316 | gif | virgo_J2.fits |
| 11 | 5 | 8723.0 | 3643.0 | 183.72972 | 13.46134 | 20.0 | 1.000 | 0.0 | j | 13.856 | 0.282 | gif | virgo_J2.fits |
| 1 | 6 | 681.0 | 2418.0 | 190.61783 | 12.43990 | 10.0 | 1.000 | 0.0 | j | 15.155 | 0.464 | gif | virgo_J2.fits |
| 5 | 6 | 3787.0 | 2651.0 | 187.96327 | 12.65685 | 20.0 | 1.000 | 0.0 | j | 13.182 | 0.152 | gif | virgo_J2.fits |
| 5 | 6 | 3547.0 | 2789.0 | 188.16890 | 12.77129 | 30.0 | 1.000 | 0.0 | j | 12.976 | 0.190 | gif | virgo_J2.fits |
| 5 | 6 | 3782.0 | 2441.0 | 187.96704 | 12.48164 | 10.0 | 1.000 | 0.0 | j | 14.451 | 0.243 | gif | virgo_J2.fits |
| 6 | 6 | 4141.0 | 2632.0 | 187.66058 | 12.64171 | 10.0 | 1.000 | 0.0 | j | 11.172 | 0.019 | gif | virgo_J2.fits |
| 7 | 6 | 4882.0 | 2938.0 | 187.02690 | 12.89728 | 10.0 | 1.000 | 0.0 | j | 14.686 | 0.301 | gif | virgo_J2.fits |
| 6 | 6 | 4777.0 | 2850.0 | 187.11679 | 12.82392 | 10.0 | 1.000 | 0.0 | j | 13.853 | 0.141 | gif | virgo_J2.fits |
| 7 | 6 | 5305.0 | 2479.0 | 186.66576 | 12.51382 | 10.0 | 1.000 | 0.0 | j | 14.278 | 0.207 | gif | virgo_J2.fits |
| 2 | 7 | 916.0 | 2183.0 | 190.41440 | 12.24731 | 20.0 | 1.000 | 0.0 | j | 13.628 | 0.229 | gif | virgo_J2.fits |
| 3 | 7 | 2171.0 | 2217.0 | 189.34230 | 12.28696 | 20.0 | 1.000 | 0.0 | j | 13.936 | 0.304 | gif | virgo_J2.fits |
| 10 | 7 | 7967.0 | 2346.0 | 184.39139 | 12.38756 | 30.0 | 1.000 | 0.0 | j | 13.547 | 0.320 | gif | virgo_J2.fits |
| 1 | 8 | 168.0 | 911.0 | 191.03928 | 11.17695 | 20.0 | 1.000 | 0.0 | j | 13.955 | 0.309 | gif | virgo_J2.fits |
| 8 | 8 | 5713.0 | 1393.0 | 186.32016 | 11.60663 | 10.0 | 1.000 | 0.0 | e | 14.832 | 0.344 | gif | virgo_J2.fits |
| 1 | 9 | 509.0 | 314.0 | 190.74284 | 10.68192 | 10.0 | 1.000 | 0.0 | j | 14.817 | 0.340 | gif | virgo_J2.fits |
| 2 | 9 | 1119.0 | 59.0 | 190.22218 | 10.47653 | 30.0 | 1.000 | 0.0 | j | 13.664 | 0.357 | gif | virgo_J2.fits |
| 3 | 9 | 2369.0 | 796.0 | 189.16568 | 11.10242 | 20.0 | 1.000 | 0.0 | j | 13.709 | 0.246 | gif | virgo_J2.fits |
| 4 | 9 | 2578.0 | 595.0 | 188.98608 | 10.93676 | 20.0 | 1.000 | 0.0 | j | 14.755 | 0.645 | gif | virgo_J2.fits |
| 5 | 9 | 3376.0 | 581.0 | 188.30785 | 10.92808 | 10.0 | 1.000 | 0.0 | j | 15.073 | 0.430 | gif | virgo_J2.fits |
| 7 | 9 | 5101.0 | 504.0 | 186.84235 | 10.86667 | 20.0 | 1.000 | 0.0 | j | 12.302 | 0.069 | gif | virgo_J2.fits |
| 7 | 9 | 5236.0 | 264.0 | 186.72801 | 10.66521 | 30.0 | 1.000 | 0.0 | j | 13.658 | 0.355 | gif | virgo_J2.fits |
| 11 | 9 | 8516.0 | 331.0 | 183.94168 | 10.70014 | 30.0 | 1.000 | 0.0 | j | 13.580 | 0.330 | gif | virgo_J2.fits |
The following images show some of the largest Virgo galaxies missing from the XSC. The images belong to the 2MASS Large Galaxy Atlas (LGA), and the integrated fluxes come from the LGA. Note that even these "large" examples are low surface brightness.
NGC 4523
Image size = 4.8X4.8 arcmin
Isophotal size and mags (r, J, H, Ks): 25.5", 13.014 0.049, 12.392 0.074, 12.155 0.086
NGC 4633
Image size = 3.9X3.9 arcmin
Isophotal size and mags (r, J, H, Ks): 30.8", 12.234 0.032, 11.573 0.043, 11.382 0.054
IC 3074
Image size = 3.9X3.9 arcmin
Isophotal size and mags (r, J, H, Ks): 21.2", 13.914 0.091, 13.396 0.121, 12.984 0.160
c. Future Work
Use the full-resolution (1" pixel) mosaic of the "heart of Virgo" (approximately 1.4 X 1.4 deg) to investigate the completeness of the fainter, more compact population. Here it would be useful to overlay existing catalogs (via NED) to gleen the maximum sensitivity of the 2MASS images.[Last Updated: 2002 Oct 9 ; by Tom Jarrett]