In order to plan an imaging mission it is sometimes vital to know ahead of time the actual angle of the CCD in relation to the sky.

There are a couple of ways to find the current Position Angle (PA)or Orientation, but keep in mind that the PA of a system can change over time due to routine use and maintenance.

The easiest way to find the PA is to check the Telescope Information Page on the website.  By clicking any of the numbered links on this page, you can see data about each specific telescope - including it's PA.  Keep in mind that the PA listed on the website is an approximate value, however, as maintenance and normal use can change this slightly and in some cases - quite a bit.

This leads to the second, and much more accurate option:

Each imaging session produces a run log that is attached to the emailed Usage Receipt for that run.  Inside this log is a section that looks like this:

12:12:57 04:12:57 Plate-solve pointing image.

12:12:58 04:12:58 57 image stars found

12:12:58 04:12:58 Trying to plate solve last exposure...

12:12:59 04:12:59 Plate Solved! 32 stars matched.

12:12:59 04:12:59 Average residual is 0.62 arcsec.

12:12:59 04:12:59 Pointing error is 1.300 arcmin @ angle 313.08

12:12:59 04:12:59 True focal length is 392.1 cm.

12:12:59 04:12:59 True image center (J2000): 15h 01m 27.0s -00? 31' 29.29"

12:12:59 04:12:59 Imager sky position angle is 88.3 deg.

12:12:59 04:12:59 Performing Corrective Slew to Center Target.

12:12:59 04:12:59 Start slew to 70_7...

12:12:59 04:12:59 (wait for slew to complete)

12:13:08 04:13:08 (slew complete)


This will always appear near the very beginning of the log file, before the first image is taken.  The line highlighted in yellow will give the current accurate position angle for the system at the time of imaging.


While we do update the web site regularly, slight (and even large) variations can occur during routine operation, or more often, during maintenance of the system.  This is especially true for the systems located in Spain, California, and Utah, as iTelescope rents our piers in these locations and does not have a staff member on site.


If you do notice a variation, please let us know by contacting support, and we adjust the website accordingly.