Alignment check

No response to this, so I'll elaborate on what the consequences can be without this check. 

I booked 11 exposures of 15 minutes duration. These were taken over 3 days. The first image taken on each separate day align to one another but are off target. The current situation where I believe a realignment takes place after the first image is taken, means the remaining 8 exposures align to each other (dithering excepted) and are on target. I can choose to ditch the 3 exposures leaving 8 out of 11 to integrate, or, use all 11 and crop 9% by area.

Hi Ray,

The control software ought to be plate solving before beginning an imaging run. I use INDI/Ekos at home here and that is the way it works. I have it configured to plate solve locally on a Raspberry Pi so it is not dependent on an Internet connection to nova.astrometry.net. Perhaps RoboScopes is configured to use astrometry.net but it lost Internet connectivity. Just a thought.

Brian

Hi Brian, 

Thank you for your reply. I've only ever framed a target manually by looping exposures and adjusting position with the mount hand controller. For subsequent sessions I'd align with reference to the original framing. Real hi-tech! 

From what you explained it appears to depend which control software is being used, so that may be why it does the plate solve afterwards. If what happened to me was a one off glitch due to the mount becoming mis-aligned, then I guess it will no longer be a problem. 

Thanks for that. I'm learning more and more all the time about things from the people on this forum.  

Regards, 

Ray 

Hi Ray,

I think that polar alignment errors can be tolerated to a certain degree since all telescopes have guide cameras. That would explain why the initial slew to target is imprecise. But this should always be followed up by automated iterative plate solving that gets you within, say, 30 arc-seconds of the target. In your case I can't say exactly why plate solving failed. If we had access to log files we could track it down.

Brian

We ordinarily take a few extra frames for each order to account for the odd bad frame such as what you have mentioned Ray

We will continue to monitor everyone's feedback to ensure we provide clear and consistent data

Ray, which order was it ?

I can check then

Steve

Good morning Steve, 

Do you guys ever sleep?

The order was 098 on pier 6. I'm fairly certain that at the time the mount was not "properly" polar aligned, and when it initially slewed to the target it was off by more than it would normally have been. Possibly something that may not reoccur. Mind you that's rich of me to infer it wasn't polar aligned "properly", given that I considered just getting Polaris in the fov of the polarscope an achievement!   

Cheers, 
Ray 

No it was early days before we changed from Paramount to 10 micron and we were having some sync issues after aquire star focusing