Identification and characterization of extended sources in the 6x image data is based closely on the extended source processor used for the main survey data that is described in IV.5. A number of modifications have been made to optimize processing for the enhanced surface brightness and sensitivity of the deeper imaging. The most important changes are as follows:
|Figure 1 - J-band 6x Atlas Image with extended sources marked in red and bright stars artifacts and masked area marked in blue. The left panel shows the raw image. The middle panel shows the "mask", and the right panel shows the background-removed image.||Figure 2 - 3-color (J+H+Ks) composite of image in Figure 1, where the left panel shows the original Atlas Images and the right panel shows background-removed Images.|
|Figure 3 - J-band Atlas Image with extended sources marked in red and bright stars artifacts and masked area marked in blue. The left panel shows the raw image. The middle panel shows the "mask", and the right panel shows the background-removed image.||Figure 4 - 3-color (J+H+Ks version of image in Figure 1, where the left panel shows the original Atlas Images and the right panel shows the background-removed Images.|
|Figure 5 - 2MASS 6x Quality Assurance diagnostic plot showing the difference between 6x and All-Sky Data Release (ADR) XSC 7" circular aperture photometry of galaxies in the Abell 3558 cluster observed on 2000 May 30 UT plotted as function of All-Sky XSC magnitude. Small blue (J), green (H) and red (Ks points represent magnitude differences for individual galaxies and black point with vertical error bars are the standard deviation of difference in 0.5 mag bins.|
Important Note About Large Galaxies:
The 6x extended source processor is not modified or tuned to properly measure
large galaxies. As a result, the
6x extended source WDB and 6x-XSC do not contain accurate
measurements of extended sources that span more than one scan.
Because large galaxies are well-characterized by
the Large Galaxy Atlas (LGA) processing from the main survey, such
processing was not carried out for the 6x data.
i. Sample 6x Extended Sources
Figures 6-9 show images of a selection of extended sources extracted during 6x data processing. In each image, the left panel shows a three-color, background-removed "postage stamp" image. The right panel shows the same image with stars removed. The Ks-band (fiducial) elliptical isophotal radius is shown in the figures in blue. The isophotal elliptical Ks magnitude (k_m_k20fe), sem-imajor axis length and axial ratio of the galaxies are given in in the figure captions. Only one image is displayed for the faint galaxy in Figure 9 because no foreground stars were subtracted.
|Figure 6 - Ks=10.89 r=17.8" b/a=0.9||Figure 7 - Ks=11.06 r=21.2" b/a=0.9|
|Figure 8 - Ks=11.67 r=23.9" b/a=0.4||Figure 9 - Ks=15.46 r=5.0" b/a=1.0|
[Last Updated: 2007 January 8; by T. Jarrett and R. Cutri]