Hi Richard,

I do have an animation from the previous night too:

http://www.nickdjames.com/Comets/2020/2020f3_20200721_ndj.gif

but I have had to use shorter stacks since I had a lot of cloud on that
night. It doesn't show as much motion.

Most of the work has been scripting this process so that I can run it
automatically on all the sub images with exactly the same settings and
then vary the settings to see what works best. Now that it is scripted
it taks around 30s to process 100s of subframes into a movie (including
alignment, filtering and stretching) on my Xeon based PC.

I'm waiting for the next clear night to do a longer run.

Nick.

On 27/07/2020 16:16, Richard Miles - rmiles.btee at btinternet.com (via
baa-comet list) wrote:
> That's quite a lot of work, Nick, but well worth it - I was surprised to
> see knots of material flowing down the tail in your animation.
>
> I agree that a Theta of 10 degrees is a good choice with the L-S filter.
> Your 1.3" pixels means that 2 pixels is about 2.6", so that translates
> to 4 pixels radius or so on my system. I'll go with 3.5 pixels radius
> (0.68"/pixel).
>
> I have about 46 minutes worth of i filter imaging (~300 frames) from the
> day before (July 21) and 97 minutes  (~700 frames) from July 20. Not
> sure when I'll be able to tackle these! The comparison of 3 animations
> over 3 days might also show up something new.
>
> Cheers,
> Richard
>
> ----- Original Message ----- From: "Nick James" <ndj@nickdjames.com>
> To: <baa-comet@simplelists.com>
> Sent: Monday, July 27, 2020 1:55 PM
> Subject: Re: [BAA Comets] NEOWISE close-up
>
>
>> I've only just got around to processing my images of C/2020 F3
>> (NEOWISE) from July 22. An animation is here:
>>
>> http://www.nickdjames.com/Comets/2020/2020f3_20200722_ndj.gif
>>
>> This shows a field of view of 33x22 arcmin processed using a
>> Larson-Sekanina filter with r=2, th=10 deg. There are 9 frames each of
>> around 330s duration (from 2143 - 2228). You can clearly see motion in
>> the tail and material spiraling out from the centre of the coma. The
>> small black dot at the centre of the coma is the reference pixel for
>> the filter.
>>
>> I have done quite a few experiments with this data and I think the
>> parameters I have chosen are the best compromise to show detail and
>> motion (i.e. around 300s integrations and L-S with r=2, th=10).
>>
>> It always amazes me that so much relative motion is visible in active
>> comets over such a short period of time.
>>
>> Nick.
>>
>>
>> On 21/07/2020 12:51, Richard Miles - rmiles.btee at btinternet.com
>> (via baa-comet list) wrote:
>>> Thanks Nick.
>>> I wonder what the rotation period of the nucleus is?
>>>
>>> My 10' x 7' close-up image processed first with the Larson-Sekanina
>>> filter, the second using a rotational gradient filter is here on my
>>> BAA Members' Page:
>>> https://britastro.org/node/23409
>>>
>>> The frames spanned from 21:50-22:14 UT on 2020 July 20.
>>>
>>> Richard