[BAA Comets] Visual equivalent magnitude of C/2013 US10

[Nick James]

Got up at 4:30 this morning expecting a clear sky but actually had a 
howling gale and many fast-moving clouds. Anyway, it cleared (mostly) by 
around 05:15 and this morning's pic of C/2013 US10 can be found here:

http://www.nickdjames.com/2013US10/2013us10_20151223_0555_ndj.jpg

I get a VEM of 6.7 in a 370 arcsec radius aperture using UCAC-4 V mags. 
This is around 0.5 mags fainter than the brightest visual estimates at 
the moment and I don't yet understand why this is since the coma 
diameters reported visually are smaller than I'm getting.

Probably my last view now until early January.

Nick.