HI All,

I am happy with my computer installations for KStars and EKOS. But as you might guess I have a question. My question revolves around my specific set for the temperature regulation in EKOS.
Here is what I have:
I am running the latest version of Ubuntu 20.04 LTS.
I have installed the Bleeding edge for KStars.

I have my CGEM 9.25" telescope attached to my Dell notebook.
I have my SBIG ST-9xme CCD camera setup under KStars and using EKOS.

I have set my ccd cooing temperature to -5.00 C. I watched the changes in the temperature from room temperature down toward the desired set temperature. However, I seem to only get about 0.41 C as the temperature switches from -5.23 to -4.82 and never reading or settling on -5.00 exactly.

I checked the settings for EKOS "Options" "Capture "and the temperature threshold is set to 0.1 C, Guiding settle is set to 0.00 seconds and the dialog timeout set to 60 seconds.

Given these values am I missing something or do I not understand what I need to do to get the temperature regulation settings to reflect the desired 0.1 C threshold to work?
Or, is there something that isn't working correctly with the Bleeding edge version of the software?

Any advice will be most appreciated. Thank you for supporting these great products!
Regards,
John

Good question. What you set in Ekos in the threshold. i.e. Start capturing once the Difference between the reported temperature and the target temperature is less than 0.1 C. I think this value is probably too low by default given how most CMOS coolers work. With QSI583 camera, it was very consistent and reliable, but I haven't seen such behavior since. A more sane default value should be 0.5C

At any rate, this does NOT affect INDI. The driver should really strive to get to the temperature you request. If it keeps swinging back and forth, then they better work on their PID temperature regulation algorithm! So it's an issue either in the cooling hardware, SBIG SDK, or a combination.

On top of that, we cool our cameras to reduce noise. Have a look at your camera specs but I doubt that the difference in noise between -4°, -5° and -6° is noticeable. My ASI cameras also vary in temperature by a few tens of degrees and that settles down after an hour or so.

Well, I checked the specs on my SBIG ST-9 and it reads; Temperature Regulation ±0.1°C. Also just a note, the ST-9 has a CCD Kodak KAF-0261E + TC-237. I wonder who made the cooler for this camera. This camera is long since been removed from production and sale.

Cooling - standard Single Stage Thermoelectric,
Active Fan, Water Assist Ready
-45 C from Ambient Typical
Temperature Regulation ±0.1°C

I added the water assist to this camera.
Perhaps my next inquiry needs to be directed towards the manufacturers now being Diffraction Limited as they bought SBiG and sell their new cameras now.
Regards,
John

Sorry for not having been clear. I meant the noise levels for your camera as a function of temperature. Does the camera produce noticeably more noise at -4º compared to -6º? I'd be surprised if it did.

Having said that, +/- 0.1ºC is pretty accurate. Did you ever wait for an hour to see if the temperature settles at the requested temperature without deviating too much?

Yep, I've been watching the temperature and there hasn't been any change. I still am getting 0.2 C and the swing is from -5.2 C to -4.8 C. Okay I dropped the set temperature to -6 C and took a test image. Nope can't tell much in the difference in the noise levels...

I then took the temperature down to -10 C and got the same swing from -10.2 C to -9.8 C again, with .2 difference from what the set temperature is at -10 C. I can live with that. I was just wondering why the difference between the two different readings...
Regars,
John