2MASS North Focus Test Results for 980914 UT

Four sets of one-degree-long focus scans were obtained on the night of 980914 UT at the 2MASS North facility at Mt. Hopkins. This test was the second of several iterative tests to recheck telescope focus and collimation at the start of post-summer shutdown.

Four focus runs were obtained:

Run 1 (scans 002-008)-- Bolts on invar rods at head ring were tightened. Seven scans taken at focus settings ranging from +811 to +1111 microns in 50 micron steps.

Run 2 (scans 009-015) -- Collimation instrument installed and head ring adjusted. Secondary adjusted to be 2mm east of position at start of night. Seven scans were taken here at focus settings ranging from +943 to +1243 microns in 50 micron steps. Telescope pointing was not reinitialized here, so these scans required offsets of 170 arcsec east in RA (170 *subtracted* from dxsn and dxss parameters in PFPREP namelist) and 40 arcsec north in Dec (40 *added* to disn and *subtracted* from diss in PFPREP namelist).

Run 3 (scans 016-022) -- Collimation instrument installed again. North rod raised and south lowered. (Image shows that this was the wrong way to go but test data obtained anyway.) Secondary is now 2mm east and 2mm north of position at start of night. Seven scans taken at focus settings of +1263 to +1563 microns in steps of 50 microns.

Run 4 (scans 023-029) -- Secondary adjusted to be 2mm east and 2mm south of position at start of night. Seven scans taken at focus settings of +1398 to +1698 microns in steps of 50 microns.

The raw data for the focus test scans were processed during the 24hr QA/Tape validation processing at IPAC on 980914 (PDT) using 2MAPPS v2.0x.

The composite psf images generated for all of the focus test scans are shown in the figures below. The three rows show, respectively, the J, H and K_s images. Scan number is shown in each J image. (Note that scans 011 and 022 failed pattern matching in POSFRM, so we don't have psf images for these.)

The table below lists the scan, focus setting, telescope and head ring temperatures reported in the parameter files for each scan. Also listed are the second image moment ratios(*rat), seeing shapes (*sh), and fractional encircled energy parameters (PFRAC) derived for each of the focus test scans.

scn focus Tel_T Rng_T Jrat Hrat Krat Jsh Hsh Ksh Jpfrc Hpfrc Kpfrc

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Run 1:

002 +0810 18.7 18.0 1.323 1.293 1.445 1.354 1.394 1.473 0.2967 0.2711 0.2852

003 +0861 18.7 18.0 1.251 1.222 1.473 1.144 1.190 1.250 0.4614 0.4011 0.3759

004 +0911 18.8 18.0 1.118 1.114 1.265 1.001 1.033 1.082 0.6688 0.6517 0.5309

005 +0961 18.8 18.1 0.926 0.965 1.004 0.995 0.991 1.041 0.6847 0.7119 0.5879

006 +1011 18.8 18.0 0.797 0.814 0.776 1.076 1.057 1.086 0.5440 0.5896 0.4996

007 +1061 18.8 18.0 0.704 0.694 0.664 1.221 1.202 1.239 0.3398 0.3897 0.3914

008 +1111 18.8 18.1 0.826 0.794 0.715 1.511 1.522 1.534 0.2527 0.2949 0.3540

Run 2:

009 +0943 18.9 18.1 1.030 1.192 1.215 1.411 1.381 1.524 0.2929 0.2609 0.2907

010 +0993 18.9 18.0 1.039 1.055 1.302 1.174 1.177 1.251 0.4535 0.4208 0.4041

011 +1043 18.8 18.0 UNDEF UNDEF UNDEF UNDEF UNDEF UNDEF 0.6582 0.6680 0.5571

012 +1093 18.8 18.0 0.959 0.998 1.043 0.971 0.968 1.015 0.7226 0.7528 0.6310

013 +1143 18.8 18.0 0.901 0.935 0.869 1.039 1.030 1.048 0.6087 0.6377 0.5583

014 +1193 18.8 17.9 0.796 0.916 0.719 1.210 1.182 1.188 0.3664 0.3640 0.3739

015 +1243 18.8 17.9 0.872 0.830 0.766 1.494 1.438 1.474 0.2518 0.2583 0.2833

Run 3:

016 +1263 18.7 17.9 1.593 1.504 1.598 1.521 1.611 1.629 0.3191 0.3077 0.3417

017 +1313 18.7 17.9 1.646 1.576 1.691 1.279 1.350 1.421 0.3958 0.3773 0.3931

018 +1363 18.8 17.9 1.311 1.449 1.540 1.151 1.182 1.239 0.4646 0.4501 0.4047

019 +1413 18.7 17.9 0.951 1.020 1.202 1.089 1.098 1.142 0.5251 0.5278 0.4354

020 +1463 18.7 17.9 0.703 0.770 0.731 1.157 1.137 1.172 0.4509 0.5011 0.4146

021 +1515 18.7 17.9 0.521 0.596 0.565 1.291 1.283 1.303 0.3743 0.4706 0.4434

022 +1562 18.7 17.9 UNDEF UNDEF UNDEF UNDEF UNDEF UNDEF 0.3191 0.4280 0.4568

Run 4:

023 +1397 18.5 17.6 1.067 1.195 1.222 1.486 1.445 1.583 0.2553 0.2380 0.3381

024 +1448 18.6 17.6 1.101 1.243 1.376 1.247 1.236 1.314 0.3642 0.3432 0.3544

025 +1498 18.5 17.6 1.051 1.081 1.217 1.091 1.093 1.140 0.5419 0.5648 0.4869

026 +1548 18.6 17.6 0.967 0.982 1.074 0.988 0.981 1.023 0.6948 0.7321 0.6151

027 +1598 18.6 17.6 0.871 0.869 0.864 1.034 1.025 1.052 0.6288 0.6771 0.5990

028 +1648 18.6 17.6 0.847 0.837 0.757 1.182 1.166 1.149 0.4117 0.4385 0.4376

029 +1698 18.6 17.6 0.820 0.774 0.711 1.483 1.338 1.356 0.2823 0.2486 0.2965

The figure below shows second image moment ratio, seeing shape, and PFRAC plotted as a function of focus setting for scans 002-008. J data are plotted in blue, H in green and K_s in red.

The same as above, except for scans 009-015.

The same as above, except for scans 016-022.

The same as above, except for scans 023-029.

D. Kirkpatrick - IPAC

Last update - 14 September 1998