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Alright folks here's a snapshot of a small part of the radio sky to started off a little thread about observing with the CSIRO's #ATCA telescope 🧵 #radioastrophysics #radioastronomy #astronomy #radio #telescope

Most observations used to be conducted from CSIRO ATNF HQ but since COVID remote observing has become the norm. We use SSH tunnels - basically secure connections between my computer and the control room computer - to remotely control the telescope #ssh #remotework #virtual

Once connected the 1st step is to calibrate the #radiotelescope array. This involves observing well-known sources of #radio light which are bright and don't change too much. We also need to calibrate the #signals between the 6 different dishes of the array 📡 📡 📡 📡 📡 📡

Calibrations are critical because the #radio waves are arriving at each #antenna at a slightly different time, which would lead to garbage #data if we didn't correct for it 🗑️ The colours show us the signal between a pair of radio antennas and how their amplitudes, phases, and delays line up 🏳️‍🌈

This takes 10-30 mins (depending on observing conditions) and if everything works you should get mostly flat #signals for each baseline (pair of dishes) across all of the channels in your band - the frequency range you're observing. This is what it looks like for a calibrator source at 5.5 GHz

Some frequency bands, like the low 1.4 GHz pictured here, have LOTS of noise in the signal. This is because of #RFI (radio frequency interference) from other human-made devices and broadcasts. So turn off your📱 if you're visiting a radio #telescope site 🤫 #radioastronomy

During the observation we also need to keep an eye out for changing #weather conditions like clouds, wind, and lightning! If conditions get too bad it can impact the data quality or (in extreme cases) require a shutdown of the #telescope to avoid damaging the array 🌩️🌩️🌩️🌩️🌩️

Using a schedule file (prepared before observing) to instruct the #telescope, we look at a nearby calibrator source before AND after each observation of the #science target. This helps us take the changing #atmospheric conditions into account when you analyse the data later 🌌👨‍💻 #DataScience