Plate solve problems with ASTAP, works fine with All Sky Plate Solver

[TDunnavant]

Hello, all,

For current imaging of DSOs such as M51 and M101, I'm using an FRA 500 90-mm refractor, configured with a Tele Vue 2x Powermate. This provides an effective focal length of 1012 mm, f = 11.24.

I use a ZWO ASI533MC Pro camera, 3.76 micron pixels, 3008 x 3008, field of view with the given telescope configuration of 0.64 x 0.64 degrees.

I'm using SharpCap 4.0.9562.0, 64-bit.

I'm using ASTAP with its new D50 star database.

I can open ASTAP, feed it a raw fits file obtained during an acquisition session, and it solves very quickly.

When invoked from within SharpCap, ASTAP invariably fails to plate solve when I run my camera at the exposure and gains values I use for framing and focusing -- exposure between 2 and 8 seconds, gain around 200. To get a solution, I need to ratchet the gain up to around 600.

When invoked from within SharpCap, All Sky Plate Solver continues to succeed when I run at my standard "framing and focusing" exposure and gains values.

I'd prefer to run ASTAP because of its speed, and I'd prefer to plate solve at normal exposure and gain settings. Do any of you have advice?

[admin]

Hi,

a few things to check...

1) There is an option in the plate solving settings to send 8 bit data to the plate solving application - this may have negative effects on Astap (making it harder for Astap to find stars). Check that option is switched off.

2) Add -z 2 or maybe even -z 4 to the additional options box to ensure that Astap makes the input file smaller by a factor of 2 or 4 before trying plate solving as this can help

3) Try the latest SharpCap 4.1 beta which sends RAW images to Astap (this on the advice of Han - Astap's author). Older SharpCap versions send debayered colour images which is apparently not ideal.

Hope this helps,

Robin

[TDunnavant]

Robin,

Thanks much!

I'll give the first two suggestions a shot for now. If these don't work, I'll try SharpCap 4.1 Beta.