II. User's Guide to the 2MASS All-Sky Data Release

6. Ancillary Files

The point source catalog of the 2MASS all-sky DVD release does not conform exactly with the specified ordering of the rows (0.1 degree wide declination bands each in order of right ascension starting at the south pole). Rows are occasionally misplaced from their correct order by being displaced to a later position in the catalog. The maximum displacement error is 8543 rows. The most likely row displacement is 25 rows. The average unsigned displacement of the rows in relation to the correct ordering is 1.06 rows. As no rows are displaced northward across declination 0, the division between northern and southern hemisphere sources is correct.
The ordering into 0.1 degree wide declination bands is violated by approximately 1641 rows, each of which is displaced into the next larger 0.1 degree wide declination band.
The ordering by right ascension of each declination band is violated by approximately 1,535,880 rows, each of which is displaced to a position of larger right ascension or in a few cases as indicated above, into the next declination band.
Users who rely on exact conformity with the specification should re-sort the point source catalog. We wish to thank Henry Throop for making us aware of this error.

Sun computers running Solaris 8 and earlier versions may not be able to read the last files on some of the disk sides, because of a system driver limit of 4 GB. Solaris 8 systems with a Patch level 109764-04 and later can read past the 4 GB limit and successfully read the last file on the disks. However, systems running Solaris versions earlier than 8, even with the matching Patch 105486-07, fail to read the last files on disk sides containing more than 4 GB. One can list the Patches present in Solaris with the command:
% showrev -p .

Please report any problems encountered with the DVD-ROM to the IRSA Helpdesk.

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