[BAA Comets] Fw: Fw: [CometObs] C/2013 X1 outburst ?

[mmatti at westnet.com.au]

Hi Folks,

I understand the caution of calling it an outburst, but the morphology is 
indicative of a gasseous eruption, with a brightening amplitude of 1 
magnitude and a sharp increase in coma size.
This should follow up with obvious ion tail activity, not yet seen with this 
comet. It has been predominately dusty.
Via various visual observers, timing of the outburst appears to have 
occurred after Jan 3.07UT:mag 9.7
Jan 3.71UT mag 8.8
Jan 3.87UT mag 8.5
Jan 4.30UT  mag 8.4
Jan 4.47UT mag 8.2
Jan 5.32UT mag 8.0
Find attached photos by Justin Tilbrook showing morphology pre and post.
kind regards,
Michael Mattiazzo


-----Original Message----- 
From: Shanklin, Jonathan D.
Sent: Tuesday, January 05, 2016 9:57 AM
To: BAA Comets Discussion List ; denis buczynski
Subject: Re: [BAA Comets] Fw: Fw: [CometObs] C/2013 X1 outburst ?

I managed a brief observation this evening, as there was an unexpected 
clearance, however cloud encroached again fairly quickly.  I made it around 
a magnitude brighter than on the 31st, however I was using a different 
sequence and conditions were not good.  It did not look markedly different, 
being a similar DC3 and diameter 4' in the 25x100B.  I think it is premature 
to say that there is an outburst, as the observations are scattered and 
still adequately fitted by a normal light curve, albeit one where the comet 
is brightening rapidly.  Points to note:
It is still 2au from the sun, and receding from the earth.
Observing conditions and instrument can make a big difference to the 
apparent brightness
Different observers have different photometric sensitivities and there can 
be a magnitude or more difference in their estimates.

Jonathan Shanklin
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