ASTAP is a free stacking and astrometric solver (plate solver) program for deep sky images. It works with astronomical images in the FITS format, but can import RAW DSLR images or XISF, PGM, PPM, TIF, PNG and JPG images.
It has a powerful FITS viewer and the native astrometric solver can be used by CCDCiel, NINA, APT, Voyager or SGP imaging programs to synchronise the mount based on an image taken.
This is free and open source software.
Features include:
- Native astrometric solver, command line compatible with PlateSolve2.
- Stacking astronomical images including dark frame and flat field correction.
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- Filtering of deep sky images based on HFD value and average value.
- Alignment using an internal star match routine, internal astrometric solver.
- Mosaic building covering large areas using the astrometric linear solution WCS or WCS+SIP polynomial.
- Background equalizing.
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- FITS viewer with swipe functionality, deep sky and star annotation, photometry and CCD inspector.
- FITS thumbnail viewer.
- Results can be saved to 16 bit or float (-32) FITS files.
- Export to JPEG, PNG, TIFF( ASTRO-TIFF), PFM, PPM, PGM files.
- FITS header edit.
- FITS crop function.
- Automatic photometry calibration against Gaia database, Johnson -V or Gaia Bm
- CCD inspector
- Deepsky and Hyperleda annotation
- Solar object annotation using MPC ephemerides
- Read/writes FITS binary and reads ASCII tables.
- Some pixel math functions and digital development process
- Can display images and tables from a multi-extension FITS.
- Blink tab.
- Track and Stack function
- Photometry tab
- Inspector tab for measuring curvature.
- Mount analyse tab.
- Live stacking tab.
- Cross-platform support – runs under Linux (32 and 64 bit), Raspberry Pi (32 and 64 bit), macOS 64 bit, and Windows 32 & 64 bit.
Website: www.hnsky.org/astap.htm
Support:
Developer: Han Kleijn
License: Mozilla Public License

ASTAP is written in Pascal. Learn Pascal with our recommended free books and free tutorials.
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