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ASCOM temperature sensor?

Posted: 02 Jan 2020, 19:47
by Dunmunro
Hi all. I want to add a temperature sensor to monitor the temperature of my SCT tube, and then use that temperature to focus via the coefficient of expansion of the tube. Does any know of a suitable ASCOM supported sensor?

Re: ASCOM temperature sensor?

Posted: 04 Jan 2020, 17:03
by fabdev
Hi, there are some arduino projects, but then you will need to use scripts to program the behaviour, reading the temperature via the virtual serial port.
If you need to take a long sequence and just need to autofocus every 90 minutes, you could build a sequence like: autofocus will be launched at frame 1, 91 and 181.
Assuming that autofocus takes less than 2 minutes, you will lose less than 2% of the session time.

Re: ASCOM temperature sensor?

Posted: 06 Jan 2020, 06:32
by Dunmunro
fabdev wrote:
04 Jan 2020, 17:03
Hi, there are some arduino projects, but then you will need to use scripts to program the behaviour, reading the temperature via the virtual serial port.
If you need to take a long sequence and just need to autofocus every 90 minutes, you could build a sequence like:
seqrep.png
autofocus will be launched at frame 1, 91 and 181.
Assuming that autofocus takes less than 2 minutes, you will lose less than 2% of the session time.
Thanks.

Currently, I autofocus between each sub exposure (4 or 6 mins) because I have a very steep temperature drop at the location of my observatory located at 4500ft in the south-eastern Arizona desert and only a few hundred metres from this weather station:

http://www.skyimager.net/weather/ASVweather1.html

The temperature can fall 5C per hour and this requires refocus every few minutes due to the ~300 micron/1C coefficient of expansion in my 10in SCTs.