2MASS North Focus Test Results for 980918 UT

Three sets of one-degree-long focus scans were obtained on the night of 980918 UT at the 2MASS North facility at Mt. Hopkins. This test was the sixth of several iterative tests to recheck telescope focus and collimation at the start of post-summer shutdown.

Three focus runs (Run 10-12) were obtained in a similar fashion to those obtained on 980914n, 980915n, 980916n (Runs 1-9):

Run 10 (scans 002-008) -- Secondary adjusted to be 1mm south of position at start of 980914n. Primary mirror cell was shimmed to be aligned with secondary. Seven scans taken at focus settings of +1897 to +2197 microns in steps of 50 microns. (However, clouds were visible during this run, prompting Run 11.)

Run 11 (scans 009-015) -- Same as Run 10 except no clouds.

Run 12 (scans 016-022) -- Same as Run 11 except that the secondary fan was turned off.

The raw data for the focus test scans were processed during the 24hr QA/Tape validation processing at IPAC on 980918 (PDT) using 2MAPPS v2.0x. Scan 013 failed pattern matching in POSFRM so there are no psf images for this scan.

The composite psf images 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.

The psf images binned as a function of cross-scan position are shown in the figures below. Plotted are the best focus position (scans 005, 012, and 019) for each of the three runs.
The psf images binned as a function of cross-scan position are shown in the figures below. Plotted are the best focus position for all the scans in Run 10.
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. Scan 013 failed processing so there will be no second moment ratios or shape parameters for this scan.

scn foc Tel_T Rg_T Jrat2 Hrat2 Krat2  Jsh   Hsh   Ksh  Jpfrc  Hpfrc  Kpfrc

---------------------------------------------------------------------------
Run 10:
002 1896 17.9 16.8 1.003 0.973 1.031 1.391 1.331 1.337 0.3395 0.2855 0.3402
003 1947 17.9 16.7 0.908 0.944 1.121 1.156 1.154 1.141 0.4973 0.4847 0.4627
004 1997 17.9 16.8 0.922 0.950 1.074 1.034 1.030 1.004 0.6193 0.6728 0.6627
005 2048 17.9 16.7 0.970 0.978 0.981 1.033 1.006 0.945 0.6212 0.6968 0.7462
006 2097 17.8 16.6 0.991 0.993 0.891 1.118 1.081 1.025 0.4887 0.5949 0.6402
007 2147 17.8 16.6 1.140 1.005 0.790 1.264 1.250 1.147 0.2920 0.3596 0.3815
008 2197 17.8 16.5 1.125 1.162 0.743 1.527 1.537 1.406 0.2592 0.2644 0.3140
	
Run 11:	                                      
009 1903 17.8 16.5 1.025 1.113 1.234 1.448 1.402 1.387 0.3156 0.2828 0.2818
010 1953 17.8 16.6 0.951 0.975 1.130 1.183 1.180 1.166 0.4575 0.4637 0.4559
011 2003 17.8 16.5 0.943 0.961 1.099 1.046 1.041 1.014 0.6012 0.6485 0.6622
012 2053 17.8 16.6 0.958 0.950 0.965 1.038 1.005 0.964 0.6200 0.6973 0.7207
013 2101 17.8 16.6 UNDEF UNDEF UNDEF UNDEF UNDEF UNDEF 0.5053 0.6030 0.6322
014 2155 17.8 16.6 1.003 1.123 0.769 1.306 1.269 1.179 0.3015 0.3770 0.3864
015 2203 17.8 16.6 1.109 0.978 0.721 1.528 1.572 1.440 0.2708 0.2849 0.2798
	
Run 12:	                                      
016 1903 17.8 16.7 1.025 1.106 1.238 1.427 1.373 1.371 0.3214 0.2911 0.2911
017 1953 17.8 16.7 0.943 0.969 1.137 1.168 1.169 1.158 0.4711 0.4658 0.4593
018 2003 17.8 16.6 0.935 0.952 1.070 1.044 1.034 1.010 0.6096 0.6598 0.6712
019 2053 17.8 16.6 0.947 0.939 0.946 1.018 0.993 0.959 0.6338 0.7057 0.7366
020 2105 17.8 16.6 0.942 0.939 0.838 1.124 1.071 1.020 0.5000 0.6096 0.6158
021 2153 17.8 16.6 1.106 0.954 0.752 1.301 1.263 1.171 0.3052 0.3848 0.3879 
022 2203 17.8 16.6 1.114 1.000 0.726 1.556 1.563 1.462 0.2737 0.2918 0.3392

The figures below show second image moment ratio, seeing shape, and PFRAC plotted as a function of focus setting for scans 002-008, 009-015, and 016-022. J data are plotted in blue, H in green and K_s in red.

The figures below show the delta mags as a function of cross-scan position for each of the best focus positions (scan 005, 012, and 019) for each run.

D. Kirkpatrick - IPAC
Last update - 18 September 1998