2MASS North Focus Test Results for 980915 UT

Four sets of one-degree-long focus scans were obtained on the night of 980915 UT at the 2MASS North facility at Mt. Hopkins. This test was the third of several iterative tests to recheck telescope focus and collimation at the start of post-summer shutdown.

Four focus runs (Runs 5-8) were obtained in a similar fashion to those obtained on 980914n (Runs 1-4):

Run 5 (scans 002-008) -- This is a repeat of Run 4 from last night. Secondary adjusted to be 2mm east and 2mm south of position at start of prevoius night. Seven scans taken at focus settings of +1408 to +1708 microns in steps of 50 microns.

Run 6 (scans 009-015) -- Secondary adjusted to be 2mm east and 4mm south of position at start of previous night. Seven scans were taken here at focus settings ranging from +1545 to +1845 microns in 50 micron steps.

Run 7 (scans 016-022) -- Secondary is now 2mm east and 1mm south of position at start of night. Seven scans taken at focus settings of +1147 to +1447 microns in steps of 50 microns.

Run 8 (scans 023-029) -- Secondary is now 4mm east and 1mm south of position at start of night. Seven scans taken at focus settings of +1478 to +1778 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 980915 (PDT) using 2MAPPS v2.0x. The .par files for scans 013, 015, 016, 017, 019, 023, 026, and 027 were corrupted due to unknown factors (Mike blamed a cable-nibbling rat), so these were hand editted to match the .lgo file which Rae produced. Poor seeing was reported at the beginning of the night, and the Run 8 observations were halted and retaken later because of clouds.

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 022, 024, and 029 failed processing, so we don't have psf images for these.)

The plot below shows for each run the psfs at the position -50 microns from nominal focus . The rows again correspond to J (top), H (middle) and K_s (bottom).

The plot below shows for each run the psfs at the position +50 microns from nominal focus . The rows again correspond to J (top), H (middle) and K_s (bottom).

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 5:

002 +1408 20.0 19.3 1.352 1.343 1.566 1.363 1.341 1.494 0.2896 0.2833 0.2997

003 +1458 20.0 19.3 1.290 1.336 1.579 1.173 1.168 1.263 0.4197 0.4076 0.3859

004 +1507 20.0 19.4 1.139 1.172 1.316 1.040 1.043 1.101 0.5977 0.6092 0.4904

005 +1558 20.0 19.4 0.892 0.911 0.989 1.029 1.018 1.062 0.6232 0.6581 0.5214

006 +1608 20.0 19.3 0.721 0.723 0.733 1.094 1.074 1.094 0.5434 0.5602 0.4592

007 +1657 20.0 19.4 0.646 0.643 0.628 1.291 1.220 1.239 0.3973 0.3644 0.3725

008 +1708 20.0 19.4 0.747 0.668 0.647 1.616 1.450 1.443 0.3130 0.2824 0.3310

Run 6:

009 +1545 19.9 18.9 1.574 1.635 1.635 1.626 1.639 1.678 0.3352 0.3389 0.3346

010 +1595 19.9 19.0 1.661 1.834 1.708 1.359 1.388 1.454 0.3813 0.3702 0.3599

011 +1645 19.9 19.0 1.344 1.488 1.594 1.176 1.194 1.254 0.4280 0.3975 0.3654

012 +1695 19.9 18.9 0.985 1.009 1.201 1.118 1.124 1.160 0.4907 0.4955 0.3818

013 +1745 UNDF UNDF 0.651 0.703 0.667 1.185 1.173 1.183 0.4386 0.4719 0.3748

014 +1795 19.9 19.0 0.563 0.545 0.501 1.344 1.290 1.316 0.3961 0.3944 0.3831

015 +1845 UNDF UNDF 0.597 0.525 0.483 1.596 1.503 1.592 0.3626 0.3594 0.3990

Run 7:

016 +1147 UNDF UNDF 1.150 1.300 1.309 1.394 1.353 1.516 0.2907 0.2698 0.2890

017 +1197 UNDF UNDF 1.225 1.257 1.492 1.207 1.196 1.285 0.4030 0.3937 0.3743

018 +1247 19.7 18.8 1.123 1.166 1.302 1.058 1.059 1.105 0.5725 0.5936 0.4856

019 +1297 UNDF UNDF 0.923 0.926 1.024 0.996 0.991 1.036 0.6701 0.7155 0.5665

020 +1348 19.7 18.7 0.761 0.761 0.752 1.076 1.064 1.086 0.5477 0.5662 0.4762

021 +1397 19.7 18.8 0.679 0.678 0.639 1.288 1.219 1.240 0.3973 0.3595 0.3750

022 +1447 19.7 18.8 UNDEF UNDEF UNDEF UNDEF UNDEF UNDEF 0.3161 0.2670 0.3318

Run 8:

023 +1478 UNDF UNDF 1.426 1.554 1.384 1.464 1.440 1.540 0.2998 0.2784 0.2962

024 +1528 19.4 18.7 UNDEF UNDEF UNDEF UNDEF UNDEF UNDEF 0.4100 0.4007 UNDEF

025 +1578 19.5 18.6 1.153 1.219 1.357 1.093 1.082 1.135 0.5273 0.5602 0.4765

026 +1628 UNDF UNDF 0.905 0.923 0.972 1.077 1.057 1.094 0.5377 0.5947 0.5000

027 +1678 UNDF UNDF 0.637 0.696 0.623 1.125 1.102 1.115 0.4780 0.4996 0.4271

028 +1728 19.5 18.7 0.611 0.556 0.495 1.324 1.246 1.231 0.3882 0.3672 0.3600

029 +1778 19.4 18.7 0.712 0.652 0.579 UNDEF UNDEF UNDEF 0.3111 0.2871 0.3472

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 - 15 September 1998