I usually let it drift 10 minutes for each point, then center the star and press Enter. Focal length was 870mm, pixel size 3.76 microns, plate scale 0.89 arc sec/pixel. Seeing was average, later on

On Fri, Jun 3, 2022 at 02:48 PM, Roland Christen wrote: Actually it was 4 points, not 3, and approximately 45 - 50 minutes between each point using convenient stars near or on the 20 degree Dec line.

On Fri, Jun 3, 2022 at 02:48 PM, Roland Christen wrote: Actually it was 4 points, not 3, and approximately 45 - 50 minutes between each point using convenient stars near or on the 20 degree Dec line.

Actually it was 4 points, not 3, and approximately 45 - 50 minutes between each point using convenient stars near or on the 20 degree Dec line. The model was run near sunset time, before any imaging

>>It makes absolutely no difference if you guide or model. yep i got that. I was just clarifying what was going on thanks -- Brian Brian Valente astro portfolio

On Fri, Jun 3, 2022 at 11:50 AM, Roland Christen wrote: Below shows a short session where I used a simple Keypad Dec arc model to keep the star (Arcturus) on the crosshairs of my imaging

It makes absolutely no difference if you guide or model. The drift rate of the star is exactly the same in either case. Roland

Roland that is very illuminating Just to clarify, it sounds like you did not use guiding but did use the modeling for accurate tracking, correct? -- Brian Brian Valente astro portfolio

Below shows a short session where I used a simple Keypad Dec arc model to keep the star (Arcturus) on the crosshairs of my imaging camera. The keypad reads out the RA and Dec trim rate that is applied

Hi everyone, since yesterday I am a happy owner of an AP900 with CP4 upgrade. What a beautiful an impressive mount! Coming from a Skywatcher AZ-EQ6 driven by an ASIAIR using EQMOD, I tried to use

Roland, I sent you a private email, but when auto-guiding, the guide star is usually not far from the area being imaged, so the guide star is *also* refracted. Thus the only refraction effect is the

Mike are your stars not round? I was under the impression you just had some shift in your images-- Brian Brian Valente astro portfolio

OK I guess I misunderstood what you said about modeling. I was thinking that it would help. So, what is the secret to taking guided 5-to-10-minute images with perfectly round stars ? Mike

There is a super cheap version of Sky Safari, a more expensive one, then the Pro version. More money gets you more objects plus some other things - see their website. Eric

Great. Post some when you can. Rolando

Reporting back. I used Roland's method to determine when the Squid nebula would rise above the 2nd story of my house (using my planetarium software) and arrived at 12:35am. I am happy to report that

None of what you posted above will do anything to change what happens. I tried to explain what is happening (atmospheric refraction bends the path), but if you guys really must chase this red herring,

You are chasing a red herring down a blind alley. Rolando

I do this routinely every time I am out testing scopes and mounts. A star's position will change in the sky from beginning to end. The RA/Dec will change, so that the reported coordinates after a

Yes, the star's theoretical RA/Dec is constant. However, if you plate solve that star when it's overhead and call that the theoretical RA/Dec, then when you plate solve it at another point in the sky