So what did you do on Saturday night?
I bet it wasn’t sit in one of the worlds largest radio interferometer’s control rooms? I have to say it might sound uber-geeky but I’m totally in awe of this facility. [The Giant Metrewave Radio Telescope] is absolutely wonderful and I hope you have seen some of the photogenic side of things in my previous posts but this time I thought I would give you a bit of an insight into what I’ve done on my Saturday night.
Ok, I’m not going to lie, my Saturday night has not been just work – I have been monitoring the English Premier League – like any football fan would be. Anyway, with that omission out of the way – what have I been doing?
Well the GMRT has a telescope controller, there is no way you could use this machine without considerable training, who you basically give a command file that has all the instructions on what the telescope should do during your observing run. So the first thing, obviously before the observing slot, you produce this command file. In radio astronomy you have to have a bunch of calibrators of known structure and power (flux). Basically you start off with the flux one and use this as the scale for the rest of the observations. You then use a close by source (to your actually object) as your secondary calibrator (phase). Basically you let the telescope go and do its thing, obviously there is a lot more to this but we would get a bit technical. The other thing that is important is you choose the frequency to observe at – tonight I’m observing at 1.28GHz. You might wonder why – well this frequency relates to frequency of the emission of the object and is based on a calculation for particle in the magnetic field of the object.
So once the observation begins what do you “see” obviously in radio you just get voltage signals – and yep thats what you can “see” – you can get a plot of the antenna amplitudes:
and yep I have been watching this all night… well not all the time, just occasionally to make sure nothing goes wrong! I won’t actually have a proper “image” until I have analyzed the data in a package and that will take a while – it is also a story for another time.
I hope this has given you a better insight into my geeky evening and what you do at a radio telescope… if you ever wanted to know that is!