howto:astrometry
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howto:astrometry [2009/04/30 22:05] – corrections pkubanek | howto:astrometry [Unknown date] (current) – external edit (Unknown date) 127.0.0.1 | ||
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====== Image astrometry parameters ====== | ====== Image astrometry parameters ====== | ||
- | RTS2 is able to support on-line astrometry, with corrections being fed back to the telescope as correction | + | RTS2 is able to support on-line astrometry, with corrections being fed back to the telescope as correction |
- | * **XPLATE** and **YPLATE** - size of pixel in arcseconds in X and Y direction. This is specified by //--plate < | ||
- | * **FLIP** - that depends on readout direction and used optics. Can be also regarded as indication of negative XPLATE - e.g. arcseconds rose in different direction along X axis then is common. It is 1 for most cameras, the only exception so far is Andor, which have 0 flip for EM channel and 1 for non-EM channel. This is set in the driver and unless you put extra mirror in optics, should be correct. If needed, you can set flip with //--flip// parameter passed to camera daemon. Again, **FLIP** is visible in **rts2-mon**, | + | |
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* **ROTANG**, which is an angle of north direction from vector Y axis. It is 0 when north is up on images, 90 when north is towards left (and **FLIP** is 1). **ROTANG** changes on german equatorial mount (GEM) by 180 degrees if you cross pole and go to the opposite side of the sky - eg. from hour angle 2 to hour angle 14. Default mount **ROTANG** is specified by //-r// parameter, and shows as **MNT_ROTA** in **rts2-mon**. You can also edit it there. **MNT_ROTA** changes on GEM by 180 degrees automatically. Please be aware, that **ROTANG** written to the FITS file can be sum of different variables, all having **RTS2_DT_ROTANG** flag set when the variable is created. RTS2 sums all variables with **RTS2_DT_ROTANG** flag set to form resulting **ROTANG**, which is then written to FITS headers. Check your mount source code for details - e.g. for OpenTPL mount with derotator, derotator angle is added by this code: | * **ROTANG**, which is an angle of north direction from vector Y axis. It is 0 when north is up on images, 90 when north is towards left (and **FLIP** is 1). **ROTANG** changes on german equatorial mount (GEM) by 180 degrees if you cross pole and go to the opposite side of the sky - eg. from hour angle 2 to hour angle 14. Default mount **ROTANG** is specified by //-r// parameter, and shows as **MNT_ROTA** in **rts2-mon**. You can also edit it there. **MNT_ROTA** changes on GEM by 180 degrees automatically. Please be aware, that **ROTANG** written to the FITS file can be sum of different variables, all having **RTS2_DT_ROTANG** flag set when the variable is created. RTS2 sums all variables with **RTS2_DT_ROTANG** flag set to form resulting **ROTANG**, which is then written to FITS headers. Check your mount source code for details - e.g. for OpenTPL mount with derotator, derotator angle is added by this code: |
howto/astrometry.1241121954.txt.gz · Last modified: 2009/04/30 00:00 (external edit)