Re: What's the effect of imaging through jet stream?


Stellarvue 80mm with star shoot guide camera sitting on a tmb6” refractor and asi071 camera

On May 30, 2020, at 2:32 PM, uncarollo2 <chris1011@...> via <chris1011@...> wrote:

Are you using an off-axis guider or separate guide scope? What is the main scope you are imaging with?


-----Original Message-----
From: Cheng-Yang Tan via <cytan299@...>
Sent: Sat, May 30, 2020 12:53 pm
Subject: [ap-gto] What's the effect of imaging through jet stream?

Hi guys,
   Hopefully my question is not off topic. But here goes:

   I imaged M101 last night (alt at 76 deg and close to the meridian) with my Mach1GTO and I had to throw away 1/2 my subframes. I examined the bad subframes and there's no consistent direction for the eggy stars from each subframe. Some subframe's eggy stars were in RA direction, some were in DEC direction and some were angled w.r.t. RA and DEC. I looked at the meteoblue seeing map (attached) and it says that the jet stream was at around 31 m/s last night. PHD2 guide graph was about 0.5 arcsec rms error for the entire night which wasn't too bad for the entire session because my image scale is 2.1 arcsec/pixel.

Is the above something that I'd expect imaging through the jet stream? Or I should be looking for something else to blame like flexure?

Thanks (before I start tearing everything apart :) )


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