Guiding issues in hot weather

[Graham Smith]

It's odd to asking this in March, but we're in a heat wave in the bay area.

Last night (03/18/26) was warm with night temps in the high 60s to 70s and I started to see guiding struggle after a while and some subs with very long star streaks (attached). 

I went into PHD2 to try and troubleshoot. I saw it was getting a lot of lost stars and when I adjusted to exposure from 0.5 secs to 3 secs I saw a lot of noise in the images. I reduced the exposure to 1 secs and it looked a little better. I also ran guiding assistance and accepted the suggested values. Alas I didn't see much improvement, with guiding being quiet poor and occasionally hitting the long star streaks. 

In contrast, 2 days before I was getting great guiding (for my rig). That night was 50s to 60s, at a sight with less light pollution, with the same guide scope & camera and same software.

I'd love to get some guidance (pun intended), on likely issues. My guess is the uncooled guide camera got so noisy that PHD2 guided on noise rather than stars to cause the long streaks. Could the heat cause my EQ6R Pro mount to have binding or backlash issues?

PHD2 Guiding 2.6.14

Guide camera OGMA671

Guide scope SV165

OTA ES ED127

Imaging camera ATR2600C

https://openphdguiding.org/logs/dl/PHD2_logs_usJb.zip

[Brian Valente]

you weren't getting mount errors, you were receiving many lost star messages. the noise 'you see' is likely related to the gain in your view, and does not reflect the actual data. 

I didn't really see anywhere the guide exposure was left at anything other than 1 or 1.5 seconds

eventually things calmed down enough (or the sky position was better) that your guiding resumed to be good around 3:30

Unless there's a specific reason not to, i suggest you create a dark frames library and use that for your guide camera.

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Brian 

Brian Valente

astronomy portfolio https://www.astrobin.com/users/bvalente/ 

[Brian Valente]

PS - just to clarify, i suggest you increase the guide exposure time and use a dark library.

If your hot weather persists (and it sounds like it will) another option is to enable capturing lost star events for future nights, so we can see what those frames look like.  you can cap it at a number like 25

[Graham Smith]

Thanks for the insight

I'm pretty sure I was using a dark frames library. I will create a new one tonight as I suspect the heat may make the camera noisier than the previous library. Out of curiosity, is there a way to see the noise level in the libraries?

I will enable diagnostics for capturing lost stars when I image tonight. Yes it will be warm again.

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[Graham Smith]

Alas it was hot again tonight (still winter?), thanks to Exxonmobil, Shell, Texaco et al and guiding was awful just like last night, even after creating a new dark library. I posted the logs, https://openphdguiding.org/logs/dl/PHD2_logs_PABi.zip

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