Multi Session Imaging

[paulgrover68]

Not sure if this is the right section, but I am sure one of the excellent mods will move it if needed.

Until recently I have been a single night imager. However clouds and the rotation of the planet can stop me getting all the data I want.

Plate solving has made it really easy for me to return to a target and point exactly at where I was during the last session. 

So I plan image over a couple of nights.

But...

How do I process the data?

One night is easy - Lights, Darks, Flats, Bias + DSS = photoshop fun.

Imaging on different nights will require different flats... so do I stack different nights separately? Do I combine  the resultant TIFFs  in photoshop?  Do I stack the TIFFs in DSS? I'm just kinda guessing!

 

I've seen file groups in DSS, but there seems to be not a lot of guidance on using them.

 

So what so you guys recommend?

[Wyvern]

Do you retake your calibration frames each session? I'm pretty lazy and tend to keep mine as long as they still work or I rotate the camera.

So unless I change any of my calibration frames I just process as normal. 

[don4l]

I think that the answer depends on your setup.

When I an doing narrowband I don't need "fresh" flats.  I'm currently using flats that I took last year.

If I am doing LRGB, then I need flats between every filter change.  For whatever reason, I don't see any effects of dust bunnies with the NB filters.

Flats also seem much more important when I image with my Tal200, than when I image with my FSQ106.  I've no idea if this is due to the different focal lengths.

I shoot darks about once a year - maybe less.  I don't use bias at all - preferring flat darks for my flat frames.

 

[AstronomyUkraine]

Posted by: @paulgrover68

Imaging on different nights will require different flats.

As long as you don't rotate your camera, or change your setup, flats can be used without the need to take fresh ones. I have used flats for weeks with no problem.

[AstronomyUkraine]

Posted by: @Wyvern

I'm pretty lazy and tend to keep mine as long as they still work or I rotate the camera.

Same here. I take my image train off the mount after each session, and don't touch anything, hence no need to take flats every night.

[DaveS]

I often keep calibration frames 6 months or more, only taking new ones when the configuration changes.

The OTA etc stays on the mount unless I'm doing some major work on it.

[paulgrover68]

Generally I've been shooting fresh flats after every session - just part of the routine I do.  While I usually take the camera off, I could always leave it in place.  

For the way tend to work (one target at a time) I'd not be moving focus or camera until done. So that actually makes life super easy.

The bonus is not having to do multiple flats... I hate shooting flats.

Thanks!

[Gina]

My imaging rig stays on the mount unless I have a problem to sort out.  Unless I change something the same flats last over multiple nights and multiple objects.