ASCOM temperature sensor?

Cameras, telescopes, focusers and other hardware
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Dunmunro
Posts: 86
Joined: 10 Jan 2019, 01:11

ASCOM temperature sensor?

Post by Dunmunro » 02 Jan 2020, 19:47

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?

fabdev
Posts: 221
Joined: 03 Dec 2018, 21:43

Re: ASCOM temperature sensor?

Post by fabdev » 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: 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.

Dunmunro
Posts: 86
Joined: 10 Jan 2019, 01:11

Re: ASCOM temperature sensor?

Post by Dunmunro » 06 Jan 2020, 06:32

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.

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