Comet Photography

[Gerry Casa Christiana]

Hello all

Ive heard that it's possible to do photography of the 45P comet as it's around I hear BUT how do you do it guys and girls? What do you do for tracking? What's the slew rate? I'm using eqmod to run things. Can anyone help on settings and the like including exposure times. 

Many thanks

Gerry

[ronin]

The only answer I can thing of it that you have to make a few presumptions that may be incorrect but that hopefully do not impact on the result.

Basically you presume that it is not moving relative to the stars for the duration of your imaging of it. It will be but assuming the duration is "short" then it is treated as if "stationary" reletive to the stars. So you image it like any other object.

Agreed that overnight - 24 hours - it's position will have altered but as said that is ignored.

You will therefore need a set of RA/Dec coordinates for it each night, in order to locate it. Sidereal rate will be probably the best option, agreed it is not but it is likely not on the ecliptic not at the sidereal rate and may be going in reverse (then again Mars, Jupiter, Saturn and all the ones outside our orbit do this at one time or another).

Guess you need to get you images in a "short" time, does an hour sound fair? Certainly not half tonight and the other half the next time it is clear as the stars then cannot be aligned.

In a way I am half familiar in this as the Meade I have has no idea of The Sun. It does not exist in order to prevent you slewing off to the sun to take a peek. So to see the Sun I have to find the RA+Dec for that day and enter it as a custom object, in a similar manner. Also Solar rate is not Sidereal rate and naturally I don't have a solar rate as there is no sun. All similar to tracking this comet. My problem is during the day 2 star alignment is not easy (= damn impossible).

 

[Owmuchonomy]

7 hours ago, Gerry Casa Christiana said:

Hello all

Ive heard that it's possible to do photography of the 45P comet as it's around I hear BUT how do you do it guys and girls? What do you do for tracking? What's the slew rate? I'm using eqmod to run things. Can anyone help on settings and the like including exposure times. 

Many thanks

Gerry

Looking at some of the videos on Twitter, normal EQ sidereal is fine despite 45P being classed as a 'fast' comet.  If you are doing time lapse over a whole evening/night you may have to adjust your position slightly to keep the object centred.  Personally I wouldn't adjust the position so that the comet 'moves' through the frame.

[Bizibilder]

If using EQMOD with Carte du Ceil then you can download the comets ephimerides and it will allow you to slew to the comet easily enough.  Keep your exposure times down to a minute or two if you can and then take lots of "subs" - maybe 20-30 over an hour.  If you then use a stacking program like Deep Sky Stacker you can load your subs and get the software to "stack on comet" (for which you will need to manually tell the program where the comet is on each frame as I recall) and you will get a stack of the comet with the stars trailing on the image.

Something like this: (Comet Jaques in 2014)