VI. Analysis of the 2MASS Second Incremental Release Catalogs

7. Comparison to External Catalogs and Models

e. External Checks of 2MASS Galaxy Magnitudes

There are several ways to provide external checks on the 2MASS galaxy magnitudes. The first and simplest is to compare the galaxy aperture magnitudes with published data. Currently there are just a few major sources of near-IR aperture photometry for galaxies:

  1. The Aaronson et al. (1979, ApJ, 229, 1; 1982, ApJS, 50, 241; 1986, ApJ, 302, 536) data for IR Tully-Fisher studies which are currently in a datafile at CfA and are aperture data obtained with a single element detector in a wide field photometer on a large variety of telescopes in the late 1970's and early 1980's

  2. The Peletier, Willner, Raychaudhury et al. data on Virgo and Ursa Major obtained with a small array detector

  3. The cluster galaxy data from the Bologna group (e.g., Gavazzi et al. 1990, A&AS, 86, 109; Scodeggio et al. 1992, A&AS, 94, 299), mostly obtained at Asiago with a small array detector

  4. Cluster galaxy data from ESO, also obtained with a single element photometer (e.g., Boisson et al. 1993, A&AS, 100, 583)

  5. Photometry from the group at UNAM (e.g., Recillas-Cruz et al. 1991, A&A, 249, 312) and

  6. The Moriondo et al. (1999, A&AS, 137, 101) data for galaxies in the Pisces-Perseus region.

We have begun to compare the 2MASS aperture photometry from the data releases with these literature results. There is remarkable agreement between the 2MASS magnitudes and the literature magnitudes, even at faint magnitudes. The observed dispersion is consistent with the quoted errors and the slope is very close to unity.

The bottom of this page will contain a number of figures for the Second Incremental Data Release, including individual comparison with each published J, H, and/or K photometric data set.

For all of the comparison plots on this page, individual galaxies may appear more than once if there are more than one magnitude or aperture size given in the literature. Therefore, the number of points in the plots do not represent the number of galaxies used in the comparison. This can be seen in Figure 1, where the black points represent the data in the Release with Ks 12.2 mag, and the red points are those galaxies used in the magnitude comparisons.

Figure 1

In Figure 2 is the combined comparisons between the published data and the Release.

Figure 2

In Figures 3 and 4 is a comparison between the northern and southern hemispheres, respectively, for the Second Incremental Data Release. The data from the two telescopes is in very good agreement, the offset between the two being about 0.01 magnitudes.

Figure 3Figure 4

Below in Figures 5-8 are specific comparisons for several galaxy clusters:

Figure 5Figure 6Figure 7Figure 8
Abell 262CancerComaVirgo

Below is a breakdown for each set of published data:

Figure 9Figure 10Figure 11Figure 12

Figure 13Figure 14Figure 15Figure 16

[Last Updated: 2000 January 26 by J. Huchra and J. Mader. Modified 2000 Aug 29 by S. Van Dyk.]

Previous page. Next page.
Return to Explanatory Supplement TOC Page.