1 November 2016 at 6:49 pm #573614David SalmonParticipant
During the Alpy600 spectroscopy workshop last weekend François recommended setting a constant temperature for the imaging camera and to retain this to help with consistency across observations.
I’m guessing that typical summer night-time temperatures where I am in Oxfordshire are in the region of 10-15 C, and I have a camera that in principle can cool to around 40 degrees below ambient (I haven’t tried that yet !), so I could choose an operating temperature in the range -25 to -20 C and run with that year-round, perhaps with the exception of a few summer nights when it is particularly warm !
In the absence of other information I might start with -20 C to avoid running the camera-cooler flat-out in summer, but I’d be interested to hear about others’ experiences and what temperature/s they have chosen for their cameras and local conditions.
David1 November 2016 at 6:56 pm #577571Andy WilsonKeymaster
I have a Starlight Xpress SXVR-H694 and I usually run it at -20C. During the Winter months I sometimes run it at -25C. Of course I have to make sure I have a full set of darks and flats to match whichever temperature I use.
I agree with what Francois said, it is important to run your camera at a temperature that it can easily maintain, so that you do not get too much temperature drift. I find the temperature drifts by a few 10ths of a degree, but no more during my exposures.
Andy1 November 2016 at 9:24 pm #577574Robin LeadbeaterParticipant
Which camera do you have? Some sensors benefit from deep cooling eg the Kodak KAF CCDs. Others, like the Sony CCD, less so. The ATIK cameras I have used only cool ~25C below ambient so I run at -10C all year round which gives negligible thermal noise and saves me worrying about the risk of non matching darks/bias. Incidentally if you do cool to very low temps, watch out for ghost residual images in following exposures. This can happen for example if you take a faint spectrum image after an overexposed calibration lamp image. I have never seen it myself at -10C but it was a problem than plagued a pro-am campaign I was involved in where they were using KAF CCD cooled to a low temp.
Robin3 November 2016 at 9:16 am #577581David BoydParticipant
I also have an SX H694 and run this at -20C all year round. It seems to hold that temperature within a few tenths of a degree, even on warm summer nights.
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