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

[Arne Henden]

Results from this morning with the 1.0m, Using Richard's calibration:
   JD2453430.0286  V  17.48  0.03
   JD2453430.0348  Ic 13.23  0.03

The variable is in a crowded field with two very close companions.
The magnitudes above are aperture magnitudes that include the companions.
I will have to psf-fit the frames to do a better job, and I'll do that
after I've calibrated the field to deeper limits at BVRI in about
two weeks.
   I've placed a 4.5x4.5arcmin V-band finding chart at:
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/temp/v2361cygv.jpg
Arne


Richard Miles wrote:
> 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
> 
> 
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