2017 July

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Jul 01

03:17 UT Ant 12 is back! It will no doubt have terrible delays. Meanwhile, I am redoing my earlier calibration on 3C273 with parallel and crossed feeds, but now adding parallel and crossed feeds for the equatorial dishes. A total of four scans are being taken, in this order:

  • one with the 27-m feed tracking parallactic angle (gives parallel-feed data for azel dishes 1-8, 12),
  • one with the 27-m feed tracking parallactic angle + 90 degrees (gives crossed-feed data for azel dishes 1-8, 12),
  • one with the 27-m feed rotated by to 90-degrees (gives crossed-feed data for equatorial dishes 9-11, 13),
  • one with the 27-m feed unrotated (gives parallel-feed data for equatorial dishes 9-11, 13)

04:04 UT The first two scans worked fine, but I could not get $PA-STOP to work (should zero the FRM PA, but instead it kept sending commands to keep the feed perpendicular, overriding my FRM-SET-PA -90 command). I had to kill the schedule and reopen it. Now on the third scan as of 04:03 UT.

04:56 UT Those scans are completed. I then updated the delays (needed for ant 12, but also some very small changes to some others). All of these calibrations are "between" the ones needed for the Sun, so should not affect the calibration of those data.

Jul 03

03:20 UT I set up to do a long calibration on three sources (a repeat of my earlier special.scd, run on Jun 28) using pcal_hi-all.fsq, in order to fully test my feed-rotation correction. It will run from 07:25 UT to about 14:10 UT.

18:30 UT The feed-rotation correction works! The amplitudes are now flat over > 7 hours, and the phases behave just as expected. I wrote a memo describing the results.

Jul 05

10:21 UT I used the July 3 data to determine Bx, By and Bz corrections, mainly for Ants 12 and 13, but tweaking a couple of others. I started a new run of special.scd, but this morning I found that I made the same classic error AGAIN, using errors in meters when I really wanted them in ns. Therefore, the corrections were only about a third of those needed (but maybe at least the correct sign). I discovered it and made the correction, and got back on the source as of 10:15 UT. Hopefully by 14:05 UT when the observations end, things will be a little better. I still was not able to correct Bz for Ant 12, though, so there is one more adjustment at least, for the future.