Getting the Angle of Rotation as Close as Possible on the 2nd Night


#1

Hey guys

Up to now i’ve only spent a single night on any one target, but i’ve recently taken up doing some Bi-Colour imaging, which obviously requires spending more than one session on any given target. My query is, on the 2nd night what is the best way to get as close as possible to the framing from the 1st night? My usual workflow is as follows:

  1. Save a sequence using the FMW.
  2. Centre on the object, then rotate manually to the correct angle. I don’t have a rotator so i just eyeball this part and repeat until i’m within my margin of error (3°).

Recently on my first attempt at revisiting a target (which all went fine) i noticed afterwards that there was more rotational difference between the 2 night’s images than i was happy with. On the 2nd night, i just loaded up the original saved sequence, without realising that on this night i could have been out by +3° whereas on the 1st night it could have been -3° (so potentially the maximum difference could be as high 6° !) and i now know that this degree of error is too much for me.

Now, i know i can obviously just reduce the margin of error down to say 1° but in this case that could still potentially mean a total difference from Night 1’s images of 4°, so, long story short, is there a more straightforward way for me on the 2nd night to tell SGP to centre and rotate on one of my frames from the 1st night?
I know how to Centre on a previously saved image, but i don’ t know if SGP will tell me how much to rotate to in order to match it.

I get the feeling i’m missing something really simple here!

Cheers guys


#2

You can set up SGPro for manual rotation and it will inform you any errors you have to your allotted angle specified.
I have set made sets of full 360 degree bands that fit my cameras so when SGPro informs me of my error I can rotate my camera accordingly. As you have stipulated you are using an image from the previous night to centre your target.

Steve


#3

Hi Steve

I’m already using the manual rotator. That is how I get the framing right when I run a sequence (i.e I get the pop-up message saying to rotate x degrees clockwise/anti-clockwise). What I’m just not sure about, is how to get the same pop-up message if I choose instead to centre on a previously taken image rather than just running the sequence again.
I’m yet to try centering & rotating on a previous night’s image, and i’m sure it must be easy enough to do, so I just thought I would ask on here first.

Cheers.


#4

@xiga

  1. Open a previous image in SGPro
  2. Right click it and plate solve the image
  3. From the results dialog, choose to use the solve to set centering information for your target (make sure the target exists before solving)
  4. In the target’s settings make sure that both “center on” and “rotate to” are checked
  5. Ensure you are using a rotator and start the sequence

#5

Boom! And there it is. I knew it had to be simple :grinning:
Thanks Ken!


#6

Sorry I mi-read your post. I thought you were achieve the centring routine that Ken has so eloquently posted and that the rotation was the issue.

Steve


#7

Quick follow-up question Ken.

What if you have more than 1 target in the sequence. Does SGP always add the results of the plate solve to the 1st target in the list, or does it depend on whether certain ones are ticked?


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