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Pointing Control System

PCS takes observer requested coordinates, transform them to mount an optical axis position, commands telescope (through MCS and MCSPU), and read back axis positions to construct achieved (where the telescope is pointing) coordinates.


Try to restart PCS if it malfunctioned. Check MCPU connection and TCS error messages for possible problem descriptions.


  • slalib/tcspk/tpk stack for telescope pointing and related transformations

Testing PCS

PCS comes with a test suite, stored in pcs/test directory. There is a file, specifying how to run the tests. Tests use irc client (which needs to be in $PATH for tests to run). Screenshot below shows run of a test.


Know problems

PCS is, as any software, over-engineered in some areas and have deficiencies in the other.

Rich offsets

PCS allows for RA/Dec, Galactic coordinates, Alt-Az and DETXY offsets. RADEC and DETXY are regularly used, Galactic offsets and Alt-Az weren't used in last 3 years (so far I was able to grep in the logs). I would like to drop at least Galactic offsets options, to make the PCS code cleaner and better readable.

Only RADEC and DETXY offsets are supported for NS targets

I believe supporting Alt-Az offsets make sense for NS targets as well.

Alt-Az offsets transforms to RA-DEC

Alt-Az offsets are transformed into changes in RA/DEC target coordinates, and then RA/DEC are used. This allows the offset to change from AZ to ALT as the object sets. Also issuing Alt-Az offset and the absolute 0 0 Alt-Az offset will not move telescope back to the target position. Question is whatever we would like to mitigate this problem.

NS and S tracking on sides

The current incarnation of PCS does not allow for NS tracking on one side and sidereal tracking on the other side. This mode can be potentially usefull for e.g. obtaining asteroid and steller (callibration) spectra simultaneously.
I Attachment Action Size Date Who Comment
Screenshot-20180426154733-961x1020.pngpng Screenshot-20180426154733-961x1020.png manage 282 K 26 Apr 2018 - 22:48 PetrKubanek pcstest
VirtualTelescopes-Pointing-2002.SPIE.4848.125W1.pdfpdf VirtualTelescopes-Pointing-2002.SPIE.4848.125W1.pdf manage 188 K 20 Aug 2019 - 18:51 PetrKubanek Wallace SPIE paper 2002 - rigorous algorithm for telescope pointing
Topic revision: r5 - 20 Aug 2019, PetrKubanek
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