ASTAP and at least 10 letters

Honestly it works really well and is really fast.

If SGP doesn’t have some sort of binding agreement to use PS2, I would like to feature request that ASTAP be added to the list of potential plate solve clients. That having been said, I know there is a work around on their site to simple rename the executable and it’ll work.

But please make it official.

There is no binding agreement, Planewave is just kind enough to let us use and distribute their solver.

PS2 is not designed for integration with other apps and its usage by SGPro is hacky at best… I wonder if ASTAP has cleaner integration methods. Im not opposed to adding it, but would be very happy if it used a proper API like Pinpoint.

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From my understanding it is extremely good all around. I’ve noticed that it is now the recommended plate solver for a lot of different software. I am of course not knocking PS2 as I have been using since I bought SGP years ago and I think it is really good.

Perhaps “if it ain’t broke, don’t fix it” applies here but I am not suggesting you show PS2 the door but instead simply add ASTAP as an option. I know you have a lot of things on your plate… solve :slight_smile: so I don’t have any expectations here. Just keep it in mind the next time you have the time and energy to explore this.


P.S. seems there is source code for this program available too. :slight_smile:

ASTAP has been added in

Right now SGPro expects ASTAP to be installed in C:\Program Files\astap. If yours is not, either move it there or ping me here and I will tell you how to alter where SGPro looks for astap. Future versions will have a friendly way to do this.

OMG it is so much faster. I knew it would be but dang it is so nice to see it.

Please also add ASTAP as a blind solver option. Thank you.

For now, until UI exists to support this:

  • From the Help menu, choose “Open Log Folder”
  • In the file explorer find and open the file named “sgpro_settings.json” -> Using Notepad is fine
  • In your text editor, hit Ctrl+A (select all) and then Ctrl+C (copy)
  • Go to this website:
  • Click on the left side and hit Ctrl+V (paste)
  • Click the button that reads “Beautify”
  • On the right side, scroll to the bottom
  • Add (or modify if it’s already there) _settingAstapDirectory = "[your ASTAP path]"
  • MAKE SURE TO ADD A COMMA at the end of the line above
  • Click on the right side of the JSON viewer (on the web site)
  • Ctrl+A (select all of new text), Ctrl+C (copy it)
  • Go back to the notepad where you opened “sgpro_settings.json”
  • Ctrl+A (select all of the old json), Ctrl+V (paste the new json in)
  • SAVE “sgpro_settings.json” with your new setting


Test it:

  • Restart SGPro
  • Open the Plate Solve tab in the control panel and select the ASTAP solver
  • Click the Settings button
  • If ASTAP opens up, you’re all good

Next beta:

We will add ASTAP as a blind solver option later (pron 4.0 beta coming soon). The only reason this made it in to 3.1 is because Han K made it behave like PlateSolve2 and so there was very little work to do. Not as easy with the blind solver integration… not hard either, but could destabilize 3.1

Ok great! Looking forward to 4.0 beta.


Do any of these changes affect PS2 integration in SGPro? I will try ASTAP however PS2 also works well for me and ASTAP is yet another download for my imaging machine, which is OK, I just want to investigate ASTAP in my own time.



Nothing has changed for PS2

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ASTAP is a major increasement of PS speed IMHO

Yes it’s great to have options, I have heard a lot of good things about it and I will try it out. At the moment though I have zero problems with PS2. I am lucky enough to have a permanent set up so I just turn on my equipment, connect the equipment in SGPro and initiate my sequence. The sequence will slew and center in a timely fashion and without fail using PS2. I think the users PS2 experience depends on their particular imaging set up - my experience is very good but I know others have poor experiences with it so I am glad that we have an option to choose our plate solver.



I also have had great results with PS2. Never more than 2 seconds, so I don’t see how ASTAP can be any faster or better for me, but I might as well give it a try. Wonderful to have options. Tends to work for more people. The recent new enhancements to SGP have been coming fast and furious.


This is the first time I heard of ASTAP. Took a look at their website and downloaded the App. It interestingly has stacking too and I had been looking for a free, cross-platform equivalent to DSS to recommend to a new starter. (SiriL doesn’t do it for me). Tried it on an image set and it appeared to miss-register the images after the meridian flip, using Astrometry. Could be user error… it’s in rapid development and could just be a beta error😉

Just a PSA… people like Han are essential to this community. They build awesome software and provide it for people and apps like SGPro to use. He has a donate button on his website, but it appears to be busted. I’ve let him know. When it gets fixed, and if you use it, please donate.

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Hello Ken,

I’m the developer of ASTAP. I’m a retired electrical engineer living in the Netherlands.

Compared with PS2, ASTAP has two advantages:

  • Telescope pointing offsets of 30 degrees or more are no problem for ASTAP.
  • Focal length and pixel size setting are less critical then PS2.

The current SGP implementation is using the PlateSolve2 command-line. In the long run I would prefer that SGP would implement the ASTAP native command-line. That allows some additional setting like defining the search area in degrees. But that has no hurry. Let’s demonstrate first if the current implementation works for the SGP users.

ASTAP will behave differently then PS2 or based solvers. It should work straight out of the box and most users will not require and setting change. Just in case of solve problems, go to the following checklist:

Checklist for successful solving with ASTAP:

  • images should be preferable raw and unstretched.
  • Severe Image saturation should be avoided. Exposure time of 1, 2 5, 200 or 100x200 seconds stacked are no problem but a single 20 min exposure of the Milky Way could be a problem.
  • Stars should be pretty round. (if not is they will be skipped as double stars or galaxies)
  • Minimum of about 20 to 30 stars should be visible (this could be just above noise level. Exposure time of 1 or 2 seconds can work)
  • Image height should be at least 1000 pixels.
  • Image height in degrees should be defined within maybe 30% accuracy or better. (so in SGP the focal length, sensor size should be set correctly)

For the last point, if you open in ASTAP viewer an unsolved FITS image saved by SGP, the image dimensions in degrees as shown in the ASTAP status bar should be correct. After a solve in the viewer the image dimensions will be updated and should be the same. If they change a lot after a solve in the ASTAP viewer, you better update the focal length, sensor size settings in SGP.

A more extended checklist is available at:

p.s. the donation button has fixed.



Hi Han!

We will absolutely go back and retrofit in whatever way seems best (after the 3.1 release). I am wondering though, before we did this, if you had ever given any though to creating a localhost API server for requesting plate solves. Integrating with command line tools can be very fragile and a lot of the commands given by SGPro are “blind”. This can result in a situation where users are unaware of what happened when things go wrong.

Either way, thank you for ASTAP… it looks absolutely fantastic.

I just installed ASTAP. It was so quick and easy.

Download/install the program. Download/install the catalog. DONE.

Works really well. About 3 seconds to solve for me. That’s actually much faster than PS2 when you add in the display time PS2 tacks on at the end.
Nicely implemented Ken.
Great program Han. Thanks.

Yah that is one of the things I like about it. That 10 second close box timer on PS2 adds up like crazy when I do a model run of 100 points. 100 X 10 = 1000 seconds of close dialog box delay…