Routine maintenance and upgrades to the 2MASS telescopes and cameras were carried out over the course of Survey operations. A history of changes to the 2MASS instruments is summarized in this timeline. In some cases, changes to the instruments such as recollimation and replacement of the northern H-band array necessitated changes to data processing pipeline parameters and input files. In other cases, small shifts in pupil masks due to normal telescope motions necessitated small adjustments in image masks and flat-fields.
For bookkeeping in the pipeline processing, the northern and southern processing is divided into discrete hardware periods defined by the various changes to the telescope and camera systems. In Table 1 is listed the hardware periods used to control input parameters for point source photometry. These dates are recorded in the file /2massd/ops/histn/prophot_V3/maskdat.
| Period | Start Date (UT) | End Date (UT) |
| a | 970000 | 980604 |
| b | 980605 | 980918 |
| c | 980919 | 981023 |
| d | 981024 | 990723 |
| e | 990913 | 050000 |
Note - Periods c and d above use the same PSFs.
Only one hardware period was used for southern observatory data processing, and therefore one set of PSFs.
Sets of production PSFs were generated for each hardware period
in which there was a significant change to the optical train of
the telescopes, usually a recollimation. PSFs were generated
for 23 seeing "bins" in each band for each period. The PSF
used for profile fitting R2-R1 sources is denoted by the ?_psfid
value listed in the source record in the Point Source Working Database.
Table 2 lists the identification of each PSF (psfid) for each
hardware period and the lower edge of the seeing shape
bin to which each PSF corresponds. Recall that seeing shape
is related to image FWHM by the approximate relation:
Table 2 - Shape Bins and Identifications of Production PSFs
North period a: 0.800 j09531 0.960 j09661 0.980 j09911 1.000 j10091 1.020 j10311 1.040 j10471 1.060 j10711 1.080 j10911 1.100 j11091 1.120 j11281 1.140 j11491 1.160 j11691 1.180 j11871 1.200 j12091 1.220 j12311 1.240 j12521 1.260 j12711 1.280 j12921 1.300 j13071 1.320 j13301 1.340 j13501 1.360 j13781 1.390 j14031 0.800 h09471 0.960 h09711 0.980 h09891 1.000 h10101 1.020 h10301 1.040 h10481 1.060 h10691 1.080 h10891 1.100 h11101 1.120 h11291 1.140 h11501 1.160 h11701 1.180 h11861 1.200 h12131 1.220 h12291 1.240 h12501 1.260 h12721 1.280 h12881 1.300 h13081 1.320 h13291 1.340 h13511 1.360 h13761 1.390 h14041 0.800 k09261 0.940 k09481 0.960 k09701 0.980 k09901 1.000 k10081 1.020 k10291 1.040 k10501 1.060 k10701 1.080 k10901 1.100 k11111 1.120 k11301 1.140 k11511 1.160 k11711 1.180 k11881 1.200 k12101 1.220 k12301 1.240 k12511 1.260 k12681 1.280 k12891 1.300 k13091 1.320 k13311 1.340 k13491 1.360 k13771 1.390 k14021 North period b: 0.900 j09752 0.980 j09902 1.000 j10092 1.020 j10302 1.040 j10522 1.060 j10692 1.080 j10882 1.100 j11082 1.120 j11292 1.140 j11472 1.160 j11682 1.180 j11882 1.200 j12092 1.220 j12322 1.240 j12492 1.270 j12912 1.300 j13102 0.900 h09762 0.980 h09932 1.000 h10082 1.020 h10312 1.040 h10482 1.060 h10672 1.080 h10902 1.100 h11072 1.120 h11302 1.140 h11482 1.160 h11692 1.180 h11902 1.200 h12112 1.220 h12282 1.239 h12552 1.270 h12782 1.300 h13342 0.900 k10122 1.020 k10272 1.040 k10512 1.060 k10702 1.080 k10892 1.100 k11092 1.120 k11312 1.140 k11502 1.160 k11712 1.180 k11872 1.200 k12122 1.217 k12332 1.240 k12572 1.270 k12832 1.300 k13392 North periods c & d: 0.800 j09423 0.945 j09523 0.960 j09713 0.980 j09903 1.000 j10093 1.020 j10303 1.040 j10483 1.060 j10703 1.080 j10903 1.100 j11103 1.120 j11293 1.140 j11503 1.160 j11703 1.180 j11913 1.200 j12093 1.220 j12323 1.240 j12483 1.260 j12663 1.280 j12873 1.300 j13083 1.320 j13253 1.340 j13493 1.360 j13753 1.390 j14043 0.800 h09383 0.940 h09503 0.960 h09733 0.980 h09873 1.000 h10083 1.020 h10293 1.040 h10463 1.060 h10693 1.080 h10883 1.100 h11063 1.120 h11323 1.140 h11543 1.160 h11713 1.180 h11893 1.200 h12103 1.220 h12303 1.240 h12513 1.260 h12713 1.280 h12883 1.300 h13073 1.320 h13303 1.340 h13503 1.360 h13763 1.390 h14053 0.800 k09223 0.924 k09273 0.940 k09543 0.960 k09683 0.980 k09923 1.000 k10073 1.020 k10313 1.040 k10493 1.060 k10753 1.080 k10923 1.100 k11113 1.120 k11303 1.140 k11493 1.160 k11693 1.180 k11883 1.200 k12113 1.220 k12313 1.240 k12503 1.260 k12703 1.280 k12903 1.300 k13113 1.320 k13313 1.340 k13513 1.360 k13743 1.390 k14063 North period e: 0.800 j09334 0.940 j09524 0.960 j09644 0.980 j09874 1.000 j10104 1.020 j10304 1.040 j10504 1.060 j10724 1.080 j10894 1.100 j11104 1.120 j11314 1.140 j11504 1.160 j11714 1.180 j11884 1.200 j12094 1.220 j12304 1.240 j12504 1.260 j12714 1.280 j12874 1.300 j13104 1.320 j13324 1.340 j13504 1.360 j13754 1.390 j14004 0.800 h09154 0.920 h09294 0.940 h09464 0.960 h09654 0.980 h09884 1.000 h10114 1.020 h10314 1.040 h10494 1.060 h10704 1.080 h10914 1.100 h11094 1.120 h11294 1.140 h11494 1.160 h11694 1.180 h11894 1.200 h12104 1.220 h12314 1.240 h12494 1.260 h12724 1.280 h12904 1.300 h13114 1.320 h13304 1.340 h13524 1.360 h13744 1.390 h14054 0.800 k09344 0.940 k09504 0.960 k09704 0.980 k09904 1.000 k10074 1.020 k10284 1.040 k10514 1.060 k10734 1.080 k10924 1.100 k11114 1.120 k11334 1.140 k11484 1.160 k11684 1.180 k11904 1.200 k12114 1.220 k12324 1.240 k12514 1.260 k12704 1.280 k12884 1.300 k13094 1.320 k13264 1.340 k13534 1.360 k13764 1.390 k14034 South: 0.800 j09155 0.920 j09315 0.940 j09535 0.960 j09695 0.980 j09875 1.000 j10075 1.020 j10285 1.040 j10515 1.060 j10705 1.080 j10885 1.100 j11095 1.120 j11355 1.140 j11495 1.160 j11695 1.180 j11905 1.200 j12085 1.220 j12325 1.240 j12505 1.260 j12715 1.280 j12905 1.300 j13095 1.320 j13275 1.340 j13525 1.360 j13755 1.390 j14045 0.800 h09115 0.920 h09325 0.940 h09505 0.960 h09715 0.980 h09895 1.000 h10085 1.020 h10305 1.040 h10495 1.060 h10675 1.080 h10905 1.100 h11085 1.120 h11285 1.140 h11475 1.160 h11705 1.180 h11915 1.200 h12105 1.220 h12345 1.250 h12615 1.280 h13025 1.320 h13415 1.360 h13735 1.390 h14075 0.800 k09355 0.940 k09545 0.960 k09705 0.980 k09905 1.000 k10095 1.020 k10315 1.040 k10505 1.060 k10715 1.080 k10915 1.100 k11105 1.120 k11315 1.140 k11485 1.160 k11725 1.180 k11885 1.200 k12125 1.220 k12305 1.240 k12515 1.260 k12665 1.280 k12865 1.300 k13055 1.320 k13295 1.340 k13555 1.360 k13705 1.390 k14055
Last Updated: 1 May 2002
R. Cutri - IPAC