Pinpoint Guider Calibration MaximDL Plugin
This MaximDL plugin is used to accurately and quickly calibrate the guider speed and angle, which is later used by Maxim while guiding a long exposure.
Historically, this calibration was performed by
selecting a star on a guide cam exposure, then moving the mount for
10-20 seconds and seeing how the star moved. This process was repeated
in both directions on both axes.
This measurement process was quite
slow and sometimes imprecise, since it relied on the single star
centroid measurement being accurate, plus it was impacted by backlash
in the mount gears giving low readings.
The way this plugin works is that it analyzes a plate-solved exposure which was taken using the guide camera, using the results of the plate solution to determine the exact camera angle and rate.
The plugin will work with images solved using either the full version of Pinpoint or the LE version shipped with MaximDL.
The plate solution of the image requires that there are sufficient
stars to compare to the catalog, this shouldn't be an issue for
external guide scopes, but dual ccd cameras or those using off-axis
guiders may have too narrow a fov to solve.
A future version of the
plugin may allow its use with dual ccd cameras with a narrow fov, by
using a solved main ccd image and translating the data to the smaller
guide ccd.
Usage:
Take an exposure through the guide camera with sufficient duration to get enough stars to plate solve.
Plate solve the image using pinpoint.
Run the plugin, which will prompt the user to enter the mount guide rate, in fractions of sidereal tracking rate, e.g. 1, 0.5, 0.25 etc.
The plugin will display the results on the screen and also automatically set the guide parameters within MaximDL.
NB. The computed guide rates will be normalized to Dec=0 so you should enable Declination compensation in the Maxim guider settings to allow it to adjust the rates according to the current mount Declination value.
Config options:
· Mount guide rate in fractions of sidereal rate, e.g. 1, 0.5, 0.25 etc.
Version history:
v1.0 - Initial release.
PinpointGuiderCalibration v1.0
If you download this to give it a go, please post feedback on the MaximDL
Yahoo group, or email me directly at: winfij_AT_gmail_DOT_com
One final note - if you have any errors, please note the exact error messages
and let me know!
Regards,
John