Tweaking PlateSolve2 settings

[macdonjh]

I had trouble with PlateSolve2 last night and looking at a couple of pop-ups see some things I don’t understand. Perhaps you can help me.

First, there are some things I don’t understand in the Plate Solving pop-up:

In Step 1, why is the image scale not listed? It seems like it should be, it’s necessary to compare SGP’s current image with the database. I have my scope and camera data entered in my Equipment Profile.

I must be confused about Chain Solver operation. When I clicked Center I was given three choices based on my Equipment Profile for Plate Solving: Astrometry.net, PlateSolve2 and Chain Solver. In this case I chose Astrometry.net. I expected three attempts by Astrometry.net, but that’s not what happened. At the end of the first iteration Astrometry.net provided a pointing error, but then moved on to PlateSolve2, which crunched for more than five minutes and failed. Astrometry.net started up again, provided a second, smaller, pointing error and then started PlateSolve2 again. PlateSolve2 failed again and I think Plate Solving quit. Luckily I was close enough: my target was in my FOV.

I looked at my PlateSolve2 settings and have more questions.

The first thing which jumps out at me is the latitude/ longitude aren’t correct. Is providing PlateSolve2 with the correct location important? If so, how do I do it? I manually entered the coordinates and then exited PlateSolve2 settings. When I opened the Settings again, those same, incorrect, coordinates where there. I closed Settings again. I opened a Sequence, clicked on the Scope Centering module, Settings, PlateSolve2 (the gear icon), finally Edit Parameters. Same incorrect coordinates. My sequence refers to the correct User Profile, which has the correct latitude and longitude.

Note: the screen shot above was taken during my imaging session, so apparently PlateSolve2 is getting the correct location from somewhere.

Min Star Size of 3 pixels/ 0.9", seems reasonable to me for my image scale. I don’t think I have any stars smaller than that. What does Max Star Size 6 sigma mean? Does PlateSolve2 deterine what objects in the image are stars, compute an average HFD, then include anything which is within a 6-sigma envelope of the smallest star? With my focal length (5250mm nominal), my stars get pretty bloated, 13 HFD is common. Is that within 6 sigma? How would I know?

What does Detection Threshold do?

A general, open-ended question: is there anything I should consider changing to help PlateSolve2 work faster? It’s been taking more than five minutes to sort through 3000 areas and fail to solve my image. It used to work, so something has changed. I did change my focal length (changed mirror separation): Astrometry.net says me new focal length is 5144mm and is entered in my Equipment Profile. I don’t know what else might have changed, or maybe should be changed.

[EricC]

@macdonjh

I expected three attempts by Astrometry.net,

I’m curious why you expected this? Because there were 3 choices in the list for plate solving? That list is where you tell SGP what it should use for plate solving.

My understanding was that picking a named solver in the list, like Astrometry.net, would cause SGP to ONLY use that solver, but in your case, it apparently told SGP to START with Astrometry.net and if it failed, do the chain.

I don’t there would be any point in running the same solver multiple times with the same image - it should produce identical results.

===
Are the Latitude and Longitude in PlateSolve2’s Parameters dialog box close, or way off? I’ve never heard of a plate solver using that information, and an not sure how they would impact the results. An object is at a given RA and DEC, regardless of where you are in the world. Your latitude and longitude would impact the altitude and azimuth of the object, though.

I don’t use PlateSolve2 so can’t help with your other questions about it.
Eric C

[MSiniscalchi]

Is this a new setup you are trying to get working?
What SGP version?
I checked the plate solve setting for PlateSolve3 (don’t use PS2 anymore) and ASTAP and I don’t see where lat/lon can be set. I thought SGP gets the lat/lon location from the ‘User Profile Manager’ settings. The pixel scale is manually set in Control Panel > Plate solver > image scale (using SGP 4.5)

Mike

[macdonjh]

I’m curious why you expected this? Because there were 3 choices in the list for plate solving? That list is where you tell SGP what it should use for plate solving.

Because I have my plate solving set up to make three attempts before quitting. So, what I meant in my first post is since I chose Astrometry.net rather than ChainSolver, I expected Astrometry.net to make up to three attempts to successfully plate solve and then either tell me it passed or failed. If I’d selected ChainSolver, I’d have expected Astrometry.net → PlateSolve2 → Astrometry.net, etc.

I’m using v4.4.x. I haven’t figured out where to download PS3, I’d like to try it. I think SGP does send my location information from my User Profile to PS2 based on the screen snip I posted in my first post. With SGP v4.4 and PS2 I don’t see a place to manually enter image scale, so I hope SGP transfers that information from my Equipment Profile.

[EricC]

@macdonjh, thanks for the info.

I don’t remember where the plate scale setting is in SGP v4.4, but in v4.5 it here:

[MSiniscalchi]

macdonjh,

Platesolve3 can be found here: PlateSolve 3.80 5GB It’s 5.2GB but has the catalogs.

Mike

[macdonjh]

EricC: thank you. A friend of mine suggested novaAstrometry.net for finding my image scale. I uploaded an image taken with my “revised” scope and was given an image scale I used to back-calculate my focal length. I entered that in my Equipment Profile\Telescope. Apparently it worked, astrometry.net has been working well since.

Thank you MSiniscalchi. I will follow that link. PlateSolve2 has been painful to watch struggle the past couple of times I’ve had clear skies. Perhaps PlateSolve3 will be better.
[edit] Oh my gosh, I should have downloaded that overnight.

[macdonjh]

I’ve got PlateSolve3.80 installed and the catalogs located and linked. I opened it, loaded a recent sub and it took all of 2.2s to plate solve the image. However, when I tried to add it to my equipment profile in SGP I got this pop-up:

The library folder SGP claims to be looking for is in the folder I entered in Tools\Options\External Programs:

Can you help me out? What did I do wrong?