Imaging a comet - Anyone know much about this?

[Peje]

22 minutes ago, geoflewis said:

Hi Pete,

I haven't done any comets for a few years, but I've tried unguided, as well as guiding on either comet nucleus or a nearby star.

This image of C/2104 Q2 Lovejoy was taken in Jan 2015, as unguided (but tracked using NEQ6) 1 min subs with my DSLR + Nikon 180mm prime camera lens wide open at F2.8. If I recall correctly I first aligned and stacked on the comet nucleus using a sigma median combine which loses the star trails, then blended that with a 2nd stack aligned on the stars also using median combine to lose the comet.

To give an idea how fast some comets move against the background stars please see the below gif of Comet C/2013 US10 Catalina comprising 32x2 minute subs, so just over 1 hour duration. This image was taken through my 4" APO guiding on the comet nucleus.

....and a static image from the same 32 subs using the double stack method as described for Lovejoy - note that trails for some of the brighter stars are still showing...

Good luck, they are fun to do.

Cheers, Geof

Thanks for that great info, it's very useful. Moving back to the DSLR will be advantageous as it gives me a nice large FoV so I'll have plenty of scope to crop away rough edges.

I think the plan will be to go for 1min subs, possibly guided, and aim for a couple of hours of data.

That should offer me enough detail in the comet while also giving me a good starfield. From there I think the PI comet script should get me close to where I want to be.

A good thing about this method is I can practice it with the comet being dim, that should give me a feel for how well it's going to work.

[Peje]

10 hours ago, geoflewis said:

To give an idea how fast some comets move against the background stars please see the below gif of Comet C/2013 US10 Catalina comprising 32x2 minute subs, so just over 1 hour duration. This image was taken through my 4" APO guiding on the comet nucleus.

 

This is great info, coincidentally Catalina was the comet I failed at a few years ago! I think this thread has given me all the information I need to have a crack at comets this summer.... big thanks to everyone.

[Owmuchonomy]

17 hours ago, Peje said:

That looks really good, can you give some more capture info?

Exposure Length per sub? How many subs?

Hi Pete it was 39 x 120 secs exposures.