[BAA Comets] 174P Echeclus long exposure tonight

[Nick James]

Peter,

Many thanks for this image and for sending me the FITS files. I've 
measured the coma diameter and magnitude and these are plotted on the 
attached. The surface brightness of the outer coma is now so low that we 
are not detecting its full extent hence your latest points are some way 
off the linear prediction and these points have not been used in the 
line fit.

The figure shows a comparison between your image and an image taken 
using iTelescope T24 before Christmas. Both of these are at the same 
scale and have N up. There was a fainter patch south of the nucleus and 
in your latest image this continues with the northern half of the coma 
much brighter than the southern.

Please keep this object under observation using the deepest exposures 
you can get although, as Richard has pointed out, the two stars 
immediately to the NW will be a real pain over the next few nights.

Nick.



On 04/01/2018 22:01, Peter Carson wrote:
> Hi All,
> See http://www.astromania.co.uk/174P_20180104_1915_PCarson.jpg for my 48 
> minute exposure of 174P Echeclus earlier this evening 2017 Jan 4th. It 
> appears to be showing a faint near circular "shell". Is anyone else 
> seeing this?
> My other 174P images are here 
> http://www.astromania.co.uk/comet_174p_echeclus.html
> 
> Peter Carson
> 
> _______________________________________________
> Comets-disc mailing list
> Comets-disc at lists.britastro.org
> http://lists.britastro.org/mailman/listinfo/comets-disc

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