ASCOM temperature sensor?

[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?

[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.

[Dunmunro]

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.