|The Two Micron All Sky Survey at IPAC|
|J/H/Ks color composite of the 2MASS Combined Calibration Scan Image in rho Ophiuchus|
(2006 December 20 - Initial Release)
(2008 March 12 - LMC/SMC Data Release)
This is the release of Ancillary Data Products from the Two Micron All Sky Survey (2MASS) Extended Mission. The Ancillary Products are drawn from survey, calibration and special long exposure observations made at the 2MASS facilities at Mt. Hopkins, AZ and Cerro Tololo, Chile between June 1997 and January 2001. They are intended to complement the highly uniform and reliable All-Sky Release Point and Extended Source Catalogs and Image Atlas by providing multi-epoch images and measurements of objects observed multiple times during the survey and measurements of sources fainter than may be found in the primary survey Catalogs.
The 2MASS Extended Mission Ancillary Products do not replace the All-Sky Release Catalogs and Atlas. Rather they are intended to be used as a resource to learn more about individual objects where detailed follow-up is possible, or to conduct studies of fainter objects over small regions of the sky that do not require the high degrees of uniformity and reliability that characterize the All-Sky Catalogs. The fainter flux limits and time sampling in the 2MASS Extended Mission Ancillary Data products are obtained at the expense of reliability and uniform sky coverage. Furthermore, the Extended Mission products have not received the same level of validation and scrutiny as the All-Sky Release products. Consequently, users should defer to the source data contained in the 2MASS All-Sky Catalogs, whenever possible.
Users are encouraged to familiarize themselves with the Explanatory Supplement to the 2MASS All Sky Data Release and Extended Mission Products before using any 2MASS image, catalog, or database. Please review the Cautionary Notes sections pertaining to each Ancillary Product to learn about the limitations of the Extended Mission data.
The Extended Mission Ancillary Products are (click on product name to go to a description):
Access the Database and Image data via the NASA/IPAC Infrared Science Archive (IRSA)
||View the on-line 2MASS Explanatory Supplement|
Consult frequently asked 2MASS questions (FAQs)
Email the 2MASS Help Desk
for user support or more information
|Figure 1 - 2MASS survey depth-of-coverage map, galactic aitoff projection, showing Tile overlap regions and full Tiles observed multiple times.||Figure 2 - Cumulative area of sky plotted as a function of number of independent survey observations from repeated Tile scans.||Figure 3 - (left) Light curves of a candidate pre-main sequence star in the Orion Molecular Cloud, and (right) its evolution in the color-color and color-magnitude plane (Carpenter et al. 2001) constructed from 28 independent survey scans of the region.|
The 6x point and extended source tables are released as integrated Catalog/Working Databases. The Working Databases may contain more than one independent detection of objects scanned multiple times, and a significant number of unreliable extractions of noise and image artifacts. The 6x Point and Extended Source Catalogs (denoted by cat=1) are a uniform and reliable subset of objects in 6x Point and Extended Source Working Databases. These Catalogs are appropriate for use in statistical studies analogous to the All-Sky PSC and XSC, but over the limited areas covered by the 6x observations.
|Figure 4 - J/H/Ks color composite showing a 0.9°x0.7° region in the core of the Abell 426 (Perseus) galaxy cluster 6x field.||Figure 5 - J/H/Ks color composite showing a 0.5°x0.4° region in the core of the IC348 star formation region 6x field.|
|Figure 6 - Comparison of 6x and All-Sky PSC and XSC differential source counts in the 28.3 deg2 6x Lockman Hole field. Counts are and scaled by area.||Figure 7 - Click on this image to view a blink comparison between the color-magnitude diagrams from the 2MASS 6x-PSC and All-Sky Release PSC for objects in the 5.3 deg2 Pleiades 6x field.|
|Figure 8 - Phase-folded J and Ks light curves and magnitude-color behavior constructed using the 2977 independent measurements of an RR Lyr variable in the 90004 calibration field (courtesy A. Becker).||Figure 9 - Position of LHS 191 as a function of time from the 1839 independent observations of the 2MASS 90191 calibration field, showing the proper motion (1.022 arcsec/yr) and parallax (0.056 arcsec) of the nearby M-dwarf star. Cyan points are positions from individual calibration scans, and black points are average positions from six scans in each calibration field observation.|
In addition to the primary extracted source databases and calibrated image products from the main survey, long exposure (6x) and calibration observations, the 2MASS Ancillary Products include two "value-added" products that are designed to assist users in exploiting the multi-epoch 2MASS observations:
|Figure 10 - Click on this image to view a blink comparison between the color-magnitude and two-color Hess diagrams for sources in the 2MASS Survey Merged Point Source Information Tables and the All-Sky Release PSC within 20° of the north galactic pole. Note the improved definition of the main stellar population features for faint sources in the Merged Point Source color-magnitude diagram.||Figure 11 - Color-magnitude diagram from the 2MASS PSC (left) and Calibration Merged Point Source Information table (right) for objects in the 90067 calibration field detected more than 1000 times. Note the clear delineation of the main sequence and binary main sequence in the Merged Calibration color-magnitude diagram.|
A table of 246,760 sources detected in each of the deep, Combined Calibration Scan FITS Images is also provided. These provisional source extractions have simple aperture photometric measurements bootstrapped to the brightness of the standard stars in each Calibration field, and are useful for comparing with the results of independent extractions by users of the data.
|Figure 12 - Click on this image to view a comparison between images from a single epoch 2MASS calibration observation of the 90004 Calibration field, and the Combined Calibration image constructed using 1400 independent observations of the field.||Figure 13 - Click on this image to view a comparison between a deep 2MASS Combined Calibration image and SDSS image in the 90004 calibration field illustrating their complementary depth.|
Please include the following in any published material that makes use of the 2MASS data products:
"This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation."
Thank you very much.
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