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Comet Jacques 24/8/14


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Hi,

Okay my first attempt at imaging a comet and I didn't really know what to expect, so when I saw the fuzzy blob, I thought it was a galaxy at first.  I then spent the next half an hour finding and calibrating on nearby bright stars and when I selected comet Jacques, it went straight back to the fuzzy blob, so I figured this had to be it.  I tried a few shots at 20 secs to get focus and then decided to go to 120 and then 180 seconds on luminance.  I shot 5 or 6 before I realised that the comet was moving so fast it's core was just a streaked line.  In the end I settled for 60 secs, but even this was too much for my C11 with 0.62x FR.

If I get chance again, I will try 30 seconds.  I also didn't realise that there would be any colour to speak of so just shot 30 frames in luminance (30 mins worth) and 10 darks before packing up.

Next came figuring out how to use DSS to stack a comet, the comet menu didn't appear until I select align with no stacking and then stacking from the menu on the left.  I had to play around with all of the settings to get anything decent and Comet and Stars looked the best.  I am thinking that my scope with it's long[ish] focal length is not the best tool for the job, but I did get the comet, coma and a bit of the tail so I am pleased for a first try.

Robin

Comet Jacques, 30 frames @ 60 secs, C11, 0.62x FR, SXVR-H18, Luminance only.

Comet-Jacques-2.jpg

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Thanks guy.

I had another go last night, this time with 40 sec exposures but using RGB.  I took one L, followed by 1 R and then so on.  I manged to make 12 repeats until the cloud rolled in.  So only about 8 minutes per channel and some of them have been scrapped due to cloud or movement.  As comet Jacques gets close to earth, it's apparent motion against the background stars is increasing and this was probably my last chance with this set up until it has passed.

There was no tail visible at all, even in the luminance channel with the brightness/contrast pushed.

Robin

Comet Jacques, C11, 0.62x FR, SXVR-H18, 12 exposures per channel (L-RGB)

Jacques-26-8-14-LRGB.jpg

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I had another go last night on Comet Jacques.  I know I said it would be moving too quickly, but the clear skies were just too much of a chance to pass up.  Imaging started just before 10pm and I finished at 12:30 when the cloud eventually arrived.  I therefore have a mass of LRGB data which I haven't even started processing yet, but it looked quite good on the screen.  Watch this space....

Robin

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Hi,

Okay last nights data processed.  As comet Jacques was making it's pass by earth it meant it was moving against the star background very quickly and I had to move the mount twice to keep it in the frame.  Unfortunately, this meant that 1/3 of the frames weren't really usable as DSS had data from all frames over a relatively small area and the field is very un-even.  The following is a result of 30 frames in each of LRGB taken from the middle of the session when the mount wasn't moved. 

I find colour balance almost impossible to set, but tried on the black and on the stars to balance and comet Jacques came out very blue.  Not sure if this correct, everyone else seems to show it with more green, but it looks wrong when I try that.

Again there is no tail, perhaps it is been masked by the comet itself, or perhaps it has faded to the point where it can't be seen?

Robin

Jacques-LRGB-28-8-14a.jpg

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