[Aavso-photometry] Nova Cyg 2005 (V2361 CYG) - Dramatic fade

[Richard Miles]

Earlier today I imaged this object through V and I filters.

The nova was visible in I images (20 x 30sec stacked, 6-cm aperture) from 
which an I magnitude of 13.5 +/- 0.3 was determined.

However in V, it was fainter than V=15.5.

Previous observations have shown the nova to redden continually.  The last 
V-I measure, being made some 11 days after discovery of the nova, gave a 
value of +4.12.  Extrapolating the trend in V-I color, I estimate that this 
has now reached V = +5.7 +/- 0.7 some 17 days following discovery.

Given the I mag measure and the V-I estimate, the probable V mag at 
JD2453429.297, is V = 19.2 +/- 0.8

N.B.  It looks like this nova will have faded in V by 10 magnitudes in just 
17-18 days following its discovery.  Am not sure if this is some kind of 
record for a nova.

Clearly, more V, R or I observations of this object would be welcomed 
especially since it is likely to brighten again at some point.  Following 
the object in the I-band would seem to be appropriate.  Not sure if any 
professional observatory is in a position to take Visible/NIR spectra of 
this unusual nova.

Richard Miles