Flat light exposures after several targets


If I do several different targets in one night with Robotarget, and I use a rotator to frame them, will Voyager rotate to the correct angle for every target when I eventually do the flat frames?

Kind regards

Hi Roger,

99% of the time is not necessary to create a set of flat for each rotation or people will become crazy.
Just be sure your camera and filterwheel rotate together that for sure its true!

Anyway in the bad case you want to do flat for each rotation … you can rotate the rotator at the PA you want or use the mechanical PA stored in the FIT Headers. Use a Rotator rotate to block ad insert the PA or mechanical PA you need.

All the best

I would agree with Leonardo, with a but.

The but being that it can depend on your gear. I used to shoot sky flats every session because Voyager makes that very easy to do, but now I only do that with one of my scopes. My refractor I can recycle my flats for a long time with changes of camera angle as the camera, filter wheel and focal reducer all rotate together. Anything forward of that will be so far out of focus as to make no difference and the vignetting is quite symmetrical. My Newtonian however shows an amount of vignetting from the secondary mirror so changing the camera angle changes how that presents. For that scope I still do flats for each different camera pointing angle I have used.

Paul, you are on the 1% of cases …

I suggest to create a set of angles and do targets and flats with this angles (0,45,90,… generally what you want).

Use the DO IF EVEN/ODD DAY or DO IF DAY OF WEEK to run diffent sets of flat during the night (flat sequence files) according the array of angles.

Thanks Leonardo, that is something I had not thought of, using multiple fixed angles. That scope does not have automated rotation, so I have usually found groups of targets to shoot together at the same camera angle, that way I can use the same flats for multiple targets and still take advantage of the scheduler in Advanced to shoot multiple targets per night. Shooting flats every night is probably still an overkill, but it is in my default dragscript so if I do not need new flats I just delete them.

The real fix would cost me some money as that would be to fit a larger secondary mirror to remove that source of vignetting but I am more likely to get my roll off roof set up first.


Thanks for your input. I will need to do flats for every rotation angle. So you are saying that you can make a script that takes flats according to the fits header information? If that’s the case, my problem is solved.
As Im new to drag scripts and Voyager I would love to see what such a script would look like.

Kind regards