The program is also available at sourceforge:
Probably the best download link for high demands.
I’m a little reluctant to make a calculated comparison. PlateSolve2.exe and Astrometry.net based programs are all robust solvers. I’m confident now this also applies for ASTAP. Performance of Astrometry.net is very dependent on the settings. Each solver has it’s strengths. But generic I can say the following:
For small offsets, ASTAP solver will beat Astrometry.net in speed.
For large offsets, ASTAP will beat PlateSolve2. A test a few day ago with a 50 seconds exposure starting with a 180 degrees offset, so a full sky scan so through both Northern and Southern hemisphere took 380 seconds. So a blind solve starting with an offset of 90 degrees will be found in 190 seconds. So in practice an offset of 30 degrees will be found quickly. PlateSolve2 can’t do that. This by a brute force method, not by previously prepared index files as for Astrometry.net.
For problematic images, probably Astrometry.net is the best. For short exposures of a few seconds taken in twilight, ASTAP and PlateSolve2 have a a very similar performance. The star detection routine in ASTAP is robust.
Astrometry.net and ASTAP don’t need a correct image scale. An image scale offset of 50% can be acceptable for ASTAP. PlateSolve2 is very critical on the image scale.
Maybe not of interest for SGP, but ASTAP native executables are available for MSWindows and Linux. PlateSolve2 and Astrometry,net require an virtual environment.
Both Astrometry.net and ASTAP provide deepsky annotation. The deepsky database of ASTAP is better (based on HNSKY database)
Rather then judging my arguments, I would suggest to try it. Execute ASTAP and load a FITS image in the viewer and hit the solve button. Better hit the Σ button(ctrl+A), tab ALIGNMENT, button “Find astrometric solution current image” At the bottom have a look to the log. In this tab you can set a few things like binning for images larger then 3000 pixels wide but most likely no more settings changes are required. If you load an JPEG image, provide the expected center position in the viewer and the image height in degrees in the tab ALIGNMENT.
I you happy with the performance, rename astap.exe to PlateSolve2.exe and place it in the users directory to substitute PlateSolve2. Add the 290 files of the G17 star catalog in the same directory. Activity will be show by a small tray icon only. Confidence will be reported as 999 indicating ASTAP is reporting.
Note of warning, If you imaging at more then 3000 pixels wide, first set binning at x2 or x3 in the tab Alignment and leave the program with FILE, EXIT to save this.
ASTAP is still in active development and still beta, but soon will be at version 1.0. First solver version was released maybe in April 2018. Improvements are still included.
The internal astrometric solver works best with raw unstretched and sharp images of sufficient resolution where stars can be very faint. Heavily stretched, very long exposures or photo shopped images are problematic. It requires minimum about 30 stars in the image. Images containing of a few hundred stars are ideal. For star rich images it reduce the detection limit to limit the number of stars. This will only work for unstretched images.
This became a long piece. Hope this helps.