2017 March

Mar 02

03:05 UT The 27-m is back in service, so I am grabbing a quick 3C84 observation to check, and possibly adjust, the delays. I will plan to do a two-source observation (3C273 and 3C286) overnight, using 3bands.fsq.

03:50 UT I got good delays and set them, so now I will take a few minutes of 3C84 data as a further test with them applied. The HA on the big dish is now 49.5 degrees, and the HA limit is set to 50 degrees so that the cable alarm does not get set again by going too far. So I should see the dish hit the soft limit in a few minutes. Yep, right on schedule.

04:06 UT I have verified the delays are good (except ant 4 is still showing a lot of noise, so no delay solution). I have now set up my two-source observation to start at 07:00 UT.

10:22 UT So far, the observations have gone flawlessly, so this should be good data to get a baseline update for Bx, By and Bz. I will also be able to check pointing and feed unrotating.

Mar 05

13:30 UT Huge news! The 300 MHz correlator is working. The only known glitch is an off-by-one-slot error for the correlated data, which Jack is working on. Meanwhile, I took data all night on 3C273 and 3C286 using the new/complete science-channel definitions. The data recorded okay, and the science channels are good. However, we had no phase coherence. I discovered that the clock rate was set to 0.8 (GHz) in DPPparameters.f90. I have changed to 1.2, and am taking new data on 3C286 (the stronger 3C273 has set...).

Mar 07

15:00 UT I am back to the 200 MHz correlator, and will take some calibration (two-src) observations on 2136+006 and 2253+161, using 3bands.fsq. The scan started at 15:00 UT, but in fact with the new HA limits the source is not reachable yet. Should be reachable by the next file, at 15:10 UT.

15:30 UT Some sort of strange glitch occurred on Ant 14, and it stopped tracking without a visible error indication. I had to reboot it to recover. It is tracking again now.

18:25 UT I got a nice delay solution on source 2136+006, using delay_widget.py, and updated it. I am now taking some additional data on that source to check the delays. I am reasonably confident of the main (X) delays, but the Y-X delays may have the wrong sign.

19:07 UT I verified that delay_widget used the wrong sign of Y-X delays, so I fixed that and did one more test. The results are great! Just because I am paranoid, I am doing one last test after a very minor update in the delays. Then I will move on to test Jack's latest compile of the 300 MHz correlator.