Re: Custom Tracking Rate


Thank You Craig, that is what I was looking for.

Clear Skies, bud.


From: ap-gto@... on behalf of craig.young.m8@... [ap-gto]
Sent: Thursday, 23 March 2017 6:45 p.m.
To: ap-gto@...
Subject: [ap-gto] Re: Custom Tracking Rate

Hi Steven,

I have used custom tracking on several occasions to correct for refraction.  Here is what I do:

1. Take a 5 second image and select a star, subframe this and then take another 5 second image.

2. Using either a timer or a delay until next image, wait a period of time, say 60 seconds.  During this time measure precisely the center of the star from step 1 on the image (x,y pixel values).

3. At the end of the delay period a second image is taken and you will then see the star has moved some number of pixels in both x and y.  Again determine the center of the star and you now have two sets of pixel values (from step 1 and step 3).

4. Subtract the x and y values from measurement 2 and measurement 1, this gives you the drift in x, y over 60 seconds.  Multiply this by your plate scale to get the drift in arc-seconds.  Divide this by 60 to get arc-sec drift per second.

5. Put these two values into the custom tracking boxes and click set both now.  You should see the RA and DEC rates change on the status bar at the bottom of the APCC window.

Repeat these steps to make sure you put in the correct sign (drift direction correction) and make any further fine tune adjustments.


Join to automatically receive all group messages.