Pointing Issue

Monday, August 21, 2017 12:50 PM

Problem(s) Encountered:

Communication loss when attempting to slew to target. Telescope stop -->

telescope start --> TCS restart (& re-initialize) --> jskycalc restart resumed


Pointing error discovered immediately after this problem; the telescope slew-to-target missed the target, a miss later determined to be about (13.25, 0.5) arcmin in (RA, dec), or > 5 times the width of the field of view.

We were able to correct the pointing and resume science with a minor

modification of the example  reset telescope coordinates  procedure in the

jskycalc13m manual; instead of looking for a bright star, we used nova.astrometry.net  to determine the current field center and then fed those coordinates into jskycalc in order to  reset telescope co-ordinates.  Once this procedure was complete, the slew-to-target was close enough to correct that the science target fell within the field of view and could be centered using the paddle controls. At the end of the night, with the telescope at zenith, the encoders showed (-004, -009), which seems acceptably close to recommended rough values. This procedure requires the internet connection to work, but it does remove the need to hunt for a bright object and is reasonably quick.


Contained above.