2017 February

Feb 01

11:27 UT Started another interferometric pointing run (CALPNT), which has been running since 08:16 UT without error. The wind is low, and Ant 14 is working well.

17:35 UT Ant 14 was found to have a Dec PERMIT error on the current scan started 17:27 UT. All scans prior to this are okay. I will stop this run at 19:19 UT, in order to do a SOLPNT calibration and update the 2-m pointing, then test the result with another SOLPNT observation.

19:23 UT The pointing calibration is complete on schedule. Only one scan was messed up by the Ant14 PERMIT error. A SOLPNT measurement will start at 19:30 UT.

Feb 05

18:52 UT I found several problems today. Ant 9 crio is not working--not sure why. Ants 10, 11 and 13 were not correctly pointed (found this based on SOLPNTCAL), probably because they had an incorrect STOW at some point. I stowed them and sent them back to the Sun just now. Will redo the SOLPNTCAL. Ant 14 control system was off, and when restored I had to restart the Beaglebone computer, reset the FRM, and I also found that Ant 14 HPol is low, with no LNA Drain current. This could not be corrected--may be a hardware failure.

19:08 UT Hmm. After restowing ants 10, 11 and 13, and redoing the SOLPNTCAL, they still show very bad pointing. I am not sure what the problem is.

Feb 07

12:26 UT I finally traced the problem of pointing on ants 11 and 13 (although not 10...) to the fact that the pointing coefficients in their crio.ini files were all set to zero (and other quantities were also reset). I copied the 2016-07-09 crio.ini files back to their /ni-rt/startup directories, but these are old files, so there will need to be some tweaks. Still, hopefully today's SOLPNTCAL will find good positions.

Feb 09

18:40 UT I have continued to work on this problem of SOLPNTCALs, and I think I have finally solved it. The offsets returned from solpntanal() is added for all offsets except RA offsets on the old antennas (9, 10, 11 & 13). On those, it must be subtracted (basically it is a change to HA, which has inverted sign from RA).

23:57 UT I updated the Ant 14 pointing parameters based on the pointing measurements made on 01/27 and 02/01. I will do some additional observations to check it when possible, but right now the wind is high (> 20 mph).

Feb 10

14:11 UT Just started observations with pcal.fsq on 3C273, in order to check the pointing. The wind only just died down a bit after blowing all night, and the high winds may come back, so this will be a short observation. I hope to get an hour.