The following post is by Martha Haynes.
Last night, Derek Fertig and Jessica O’Connor, graduate students in the Department of Physics and Astronomy at George Mason University, were the A2010 observers, their 3rd night in a row. They were ready to go at 9:15pm …. but alas, the system wasn’t, and immediate ominous messages began appearing in the CIMA message window when they tried to run the calibration script command file for the TOGS program (we do the observing for the TOGS team as well as for ALFALFA). After running through his own quick check, Derek gave me a call, and I quickly logged in from my laptop at home (the only difficulty being the cat sleeping in my lap). After my own quick look at the error messages and the total power monitors — two of which read “nan” (“not a number”…. not a good sign!), I told Derek to contact the telescope operator to alert him that there was clearly a serious hardware problem…. That got an immediate response first from Arun, who was able to isolate the problem to one of the WAPPs, and then from Luis, who rushed in from home to diagnose and fix the problem (issue was a bad filter overloading a power supply). Derek and Jessica were able to restart observing at 11pm and had a successful completion of the rest of the night.
The ALFALFA survey is all about team work, not just of us astronomers but also of the technical staff who keep the instrumentation, hardware and software running day after day after day. Muchas gracias to the incredibly committed and expert staff of the Arecibo Observatory for making sure that ALFALFA catches all those photons!
The following post is by Martha Haynes.
Last night was the first night of ALFALFA observing since April. The ALFA receiver was taken down in July and reinstalled just on Tuesday (a bit late, thanks to Hurricane Irene). There hasn’t really been enough time to check it out completely and we were warned that there could be problems. Additionally, we were going to cover a drift very close to the Arecibo zenith. Betsey and Martha (along with Luke, Manolis, Melissa, Ani and Riccardo) were ready at the start. Then the big test: could we get the telescope to move to the right position for our almost-at-the-zenith declination strip (part of this is a test of the telescope software and part is a test of our ability to get the spherical geometry right). It worked! But one of the beams showed very low power, although we had been told it was ok. We double checked our setup, and in the absence of being able to do anything further, we just kept on observing.
Betsey stayed the night, but Martha came home around 12:30. She was back in the office early in the morning to check the calibration and take a quick look at the night’s dataset. She verified quickly that in fact the power in the bad beam was really low and its Tsys was too high. And so she emailed the observatory staff and they went to check (even though it was Saturday). And voila, they found the problem and fixed it. Hooray, tonight should be ok!
So, the ALFALFA team is always on duty during ALFALFA observations, because we appreciate having the chance to use the awesome Arecibo telescope and we certainly love our data. The reward today is that, in the very first drift, in the very noisy beam, there is a very bright galaxy that hasn’t been catalogued before. It’s got a lot of gas and is very blue. Now, that’s what makes ALFALFA fun!
ALFALFA: The Arecibo Legacy Fast ALFA Survey 