The shortest, toughest week of the year

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ULTRASPEC CCD defects

Despite only having 4 days, this working week has been a heavy slog. On Tuesday and Wednesday I was finishing the tests with ULTRASPEC. The bulk of the work involved creating a ‘defect mask’, which highlights all the dodgy areas of the CCD and helps observers see where to avoid placing their targets. These defects can be anything from consistently under-performing pixels to specks of dust. Unfortunately the ULTRASPEC CCD is overflowing with dodgy pixels, which meant I had to spend several hours painstakingly scouring the test images, testing the fractional difference in performance around suspected bad pixels, and ironically labelling each one either “Moderate” or “Disastrous”. The finished product is shown above.

This was desperately dull, but not as dull as testing the dark current as a function of temperature. This task had me in the lab until after midnight on Tuesday, and quite late on Wednesday too. The tests involved setting the temperature of the chip (easy enough, except that it takes 15-20 minutes for the temperature to stabilise each time), then taking 45 minutes of long exposures. The plus side of this is that I could get on with other things whilst the exposures were running (e.g. making the pixel mask, or watching cartoons, as the night went on). 

By Thursday morning I was just about halfway through the dark current tests, but I was in for a bit of a rough day. By 10am, for a still unknown reason, the electronics within the detector itself which are used to read the temperatures, went totally bananas. The CCD chip suddenly began reading values close to room temperature, despite being in a thermally cooled environment, supposedly at -100°C. In addition, the thermal conductor between the liquid nitrogen tank and the chip was displaying values around 65K. This is 10 degrees cooler than the boiling point of liquid nitrogen, and simply impossible. After checking the spare cabling and the spare temperature controller, we deduced that something was severely wrong on the inside of the detector. This was bad news, and means that the whole thing has to go back up to Edinburgh to be taken apart and tested by the experts. Balls.

The upshot of this is that I don’t have to come in on weekends and fill the cryostat, which is a relief. But I am disappointed. I was definitely expecting to finish the testing this week, and now I might not get a chance to finish at all. Thankfully, the remaining tests have been done in the past, but it would be nice to repeat them myself. 

The rest of the week has been spent catching up with the recent data collected by pt5m. Unfortunately, it was only after downloading, organising and plotting all the data that I discovered that 90% of it was pretty useless due to heavy cloud cover. So much for La Palma being one of the top three observing sites in the world!

On a positive note, I’ve now booked my travel to Paris in June, which is quite exciting. I hope I can find a couchsurfing host for it though – my travel grant is already feeling rather stretched. Other plus points of this week include seeing Ironman 3 on Wednesday which I thoroughly enjoyed, eating lunch in the sunshine, and discovering a highly motivational and enlightening video on YouTube titled “This Is Water” (google it – it’s definitely worth your time, if you can ignore the consumerist references). 

If this week has been the most mentally straining week so far, this weekend will match it perfectly in terms of physical strain. On Sunday morning I’ll be running the Sheffield Half Marathon, not because I like running (I don’t), nor because I like raising money for charity (I hate asking people to donate). I think I wanted to dedicate something to the memory of a good friend, great mentor, and fantastic lecturer, Dr Tim Richarson, who passed away earlier this year. Tim was a true inspiration for so many students and staff, and I miss him. Perhaps running 21km is a strange way to show it, but he was a brilliantly strange person. If you’d like to donate, explore the charity webpages in the link above, or alternatively, you can help destitute asylum seekers in Leicester by texting “LCOS13 £5” to 70070. 

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