[BAA Comets] 2017 S3

[David Swan]

Nick,

I thought I'd have a go with your Comphot software on my reduced 10 x 10s stacked image from 4 July - there wasn't much visible movement of the comet against the background in that time. I get the following output. Does it seem sensible?

Thanks,

David Swan

Scale: 0.99 "/pix, FoV 30.2x20.1 arcmin, PA: 26.2 deg, ZP: 26.97 mag
Sky background before normalization (non-offset): 15179.6  (16.49 mag/sqarcsec)
# Sky background before normalization (offset): 15179.6  (16.49 mag/sqarcsec)
# Sky background: 15179.6 (non-offset) 15179.6 (offset)
# RMS noise estimator has non-zero border (5)
# Residual sky background in offset stack: 0.0. RMS sky from fixed 198.5
# Centroid at 884 608, Max pixel is 5553.9
# Annulus inner radius 55.0 arcsec, ringlevel 158.0
# Annulus inner radius 71.5 arcsec, ringlevel 99.3
# Total pixels requested but outside frame: 0
#   5.6 |    101  200301 | 1983.2 1635.3   101 200301 165169 200301 | 13.72 13.72
#  11.3 |    421  446998 | 770.9 752.8   320 246697 240885 431699 | 12.85 12.89
#  16.9 |    933  722549 | 538.2 541.2   512 275551 277105 708982 | 12.33 12.35
#  22.6 |   1641 1017156 | 416.1 418.0   708 294606 295939 1008792 | 11.96 11.97
#  28.2 |   2561 1313977 | 322.6 317.8   920 296823 292339 1301828 | 11.68 11.69
#  33.8 |   3705 1603778 | 253.3 249.8  1144 289802 285790 1583402 | 11.46 11.48
#  39.5 |   5013 1866414 | 200.8 201.3  1308 262639 263342 1851587 | 11.30 11.31
#  45.1 |   6557 2116803 | 162.2 163.4  1544 250390 252219 2102661 | 11.16 11.17
#  50.8 |   8293 2350290 | 134.5 131.3  1736 233489 227908 2331346 | 11.05 11.06
 10x10  20x20  30x30  40x40  50x50  60x60
 13.72  12.85  12.33  11.96  11.68  11.46 # Counts
 13.72  12.89  12.35  11.97  11.69  11.48 # Median annuli
Total integrated magnitude: 11.06 (radius 56.4 arcsec)



________________________________________
From: Comets-disc <comets-disc-bounces at lists.britastro.org> on behalf of Nick James <ndj at nickdjames.com>
Sent: 03 July 2018 23:11:57
To: BAA Comets discussion list
Subject: Re: [BAA Comets] 2017 S3

Please keep this comet under observation and submit magnitude reports
promptly. Recent images are in our archive here:

http://www.britastro.org/cometobs/2017s3/index.html

and a chart of its position over the next couple of months is attached.

Nick.


On 04/07/2018 06:10, seargent at ozemail.com.au wrote:
>
> The sudden surge in brightness would be atypical for a dynamically new
> comet, but I suppose that this one could be a "pseudo-new" object,
> i.e. a dynamically evolved comet that was  ejected to Oort Cloud
> distances following a previous perihelion passage. Unlikely I think,
> but if that happens to be true, the survival prospects of this comet
> would look a lot better!Cheers,David
>
> ----- Original Message -----
> From: "BAA Comets discussion list"
> To:"BAA Comets discussion list"
> Cc:
> Sent:Tue, 3 Jul 2018 21:06:42 +0000
> Subject:[BAA Comets] 2017 S3
>
>       Although there is talk of 2017 S3 being bright because of an
> outburst, it may just be brightening a little more rapidly than
> expected.  Observers are suggesting that it is diffuse, yet for a
> recent outburst it should be well condensed.  I'll need some more
> observations before making any predictions, but I might be prepared to
> get up early at the beginning of August.  The comet is not well
> placed at perihelion or afterwards.
>
>     Regards,
>
>   Jonathan Shanklin

>
>
>
> _______________________________________________
> Comets-disc mailing list
> Comets-disc at lists.britastro.org
> http://lists.britastro.org/mailman/listinfo/comets-disc
>