Blogging about my astronomical endeavors - astrophoto, outreach and solar eclipse expeditions.
Sunday, March 18, 2012
Project for a cloudy day
Plot of the regions of sky where my imaging system cannot go without a pier flip.
I sometimes find that my scope can't point at the planned target due to a conflict between the camera and the tripod. The solution is to do a 'pier flip' - i.e. to rotate in RA by 180 degrees. However, after a some time tracking I'll need to flip back because now the camera-tripod conflict arises anew. I'd like to try and map out the regions of sky which are problematic so that I can take them into account when planning. Hence, during this cloudy day I set up in the living room and started mapping out what my limitations are. First, I set the scope on the west side of the mount when pointing at the meridian (I call this my 'normal' configuration), put the RA setting circle at 18hrs. Next, I put the dec. at 0,10,20,30..90 deg and for each value noted down at what (if any) RA value there was a camera-tripod conflict. I then did the same thing with the scope on the east side of the mount (I call this my 'pier flip' configuration). Using a planetarium program (time set to June 24 at midnight for which RA=18hrs passes the meridian) I then translated my RA, dec. limitation values into az, alt. values. The result is shown in the figure where zenith is in the middle and the horizon runs around the circumference with azimuth angles indicated. For each configuration I have a region where I can't point, shown in red and blue. Now, if only I could figure out a way to use this information in an easy manner to predict if and when pier flips will be required for a given object on a given date. Does anyone know of a good way to do this?