ReCal Procedure in APCC


M Hambrick
 

I have been re-reading the APCC manual and came across a statement that has me wondering if I am doing ReCals correctly. I have a portable setup, and although I usually get pretty well aligned, it is not perfect and the objects I slew to may not be centered very well in the images.

In the GoTo/ReCal tab instructions it states that you can only use the ReCal option if APCC has the target object in its memory. I will typically do a ReCal as follows:

  1. I have APCC and MaxIm DL connected to the mount (MaxIm via the AP V2 Driver).
  2. After starting everything up and getting everything going, I will slew to a bright star using the catalog and GoTo command in the MaxIm DL Observatory Control window.
  3. After the slew is complete, I take an image and see where the star lies in the image.
  4. I will center the star by using the crosshairs and right click mouse option "point telescope here" command from MaxIm.
  5. After centering the star as described above, I go to the GoTo/Recal tab in APCC and enter the RA and Dec coordinates for the star (Sirius in this case) into the boxes, then click ReCal.
  6. When the confirmation box appears, I click OK.
Is this procedure valid ? 

Mike


Roland Christen
 

Yes, your procedure is valid.

Roland

-----Original Message-----
From: M Hambrick <mhambrick563@...>
To: main@ap-gto.groups.io
Sent: Wed, May 11, 2022 9:43 pm
Subject: [ap-gto] ReCal Procedure in APCC

I have been re-reading the APCC manual and came across a statement that has me wondering if I am doing ReCals correctly. I have a portable setup, and although I usually get pretty well aligned, it is not perfect and the objects I slew to may not be centered very well in the images.

In the GoTo/ReCal tab instructions it states that you can only use the ReCal option if APCC has the target object in its memory. I will typically do a ReCal as follows:

  1. I have APCC and MaxIm DL connected to the mount (MaxIm via the AP V2 Driver).
  2. After starting everything up and getting everything going, I will slew to a bright star using the catalog and GoTo command in the MaxIm DL Observatory Control window.
  3. After the slew is complete, I take an image and see where the star lies in the image.
  4. I will center the star by using the crosshairs and right click mouse option "point telescope here" command from MaxIm.
  5. After centering the star as described above, I go to the GoTo/Recal tab in APCC and enter the RA and Dec coordinates for the star (Sirius in this case) into the boxes, then click ReCal.
  6. When the confirmation box appears, I click OK.
Is this procedure valid ? 

Mike

--
Roland Christen
Astro-Physics


Howard Hedlund
 

Hi Mike,

As Roland wrote, the procedure is valid, but be careful.  The GoTo coordinates may have been precessed into JNow, while the star coordinates you read may be J2000.  

The safest and simplest is to use the Sync in MaximDL to sync on the star.  Be sure to sync on the target star.  If you simply press sync, it may sync on the centering coordinates which will mess you up.  The synced coordinates should be consistent with regard to epoch.  The driver and APCC will convert the sync command into a recal.

HKH


M Hambrick
 

Thanks to both.

Mike