Hi folks,

The attached shows a presentation of my images for this object from this morning 11/2/21 0038 to 0305 UT (2hr 3mins of 610 longpass (ie Red+IR) data). 16" newtonian, ASI1600MM, reducer to f2.9.

The first image is stacked on the comet, and the next two images are stars from the 'star stack' of the same dataset with similar peak intensities to the comet.

I do believe its non-stellar. I've subtracted two stars from each other (bottom right, no residual), and a star from the comet, and the comet leaves distinct residuals, even when the central intensity is zero or slightly negative. Slight scaling was used to allow for differences in intensity (done in FITSWORK).

Image scale is 0.65"/pixel. Residual of ~6 pixels across implies a size of 3.9".

I took care to use two example stars from the centre of the FOV (where the comet ended up)and the edge (near where the comet started in the first images) so any variation in PSF across the sensor could be seen. None is obvious.

I think this is reasonably conclusive....! We have a comet!

Cheers

Nick

From: Nick James <ndj@nickdjames.com>
Sent: 11 February 2021 07:54
To: Nick Haigh <happylimpet@hotmail.com>
Subject: Re: [BAA Comets] C/2021 A2 NEOWISE image.

Nick,

Here's my attempt from last night. Not much evidence of cometary
activity from this.

Nick.

On 11/02/2021 00:44, Nick Haigh wrote:
> OK Im on it! You know how to press my buttons!!!!!
>
> As you say, moving fast, so its bang on one side of my sensor at 0030 and will pass off the top at 0500...should be plenty of time. I assume I can stack this.....I'll find a way.
>
> Im using coordinates off NASA Horizons...I assume theyre accurate? Fingers crossed and nothing ventured.....definitely a suitable target.
>
> Weather is saying high cloud developing but hopefully not too badly, it usually overestimates it.
>
> Cheers! Will let you know what I get.