[Aavso-photometry] V2362 Cyg's companion

[arne]

I posted in February about the companion to V2362 Cyg, as copied
below.  The photometry quoted was obtained from Sonoita Research
Observatory.  Even though it was psf-fitting, the separation of
the two stars is about 5arcsec (4 pixels) and the measurement
was difficult.

On my Flagstaff observing run, I measured the companion under
better seeing conditions and with better pixel scale, using the
1.0m telescope.  Again using psf fitting, I obtained for
JD 2454247:

star          RA(J2000) DEC           V    B-V   U-B   V-Rc  Rc-Ic   V-Ic
V2362 Cyg  21:11:32.34 +44:48:03.7  14.56  1.51  0.61  0.12  -0.31  -0.20
companion  21:11:31.88 +44:48:03.2  15.22  0.70  0.33  0.42   0.46   0.88
with separation 5.0arcsec.  Photometry errors are 0.02mag or better.

Note that the Rc and Ic magnitudes are pretty bogus, now that
V2362 Cyg is in its nebular/emission stage.

There is about a 0.1mag difference between my new measures of the
companion and the SRO analysis, which I attribute to the difficulty
in splitting this close double at SRO at a time when V2362 Cyg
was still 1.5 magnitudes brighter than its companion. Another
less likely hypothesis is that the companion is slightly variable.
For future analysis, I would use the magnitudes listed above.
Arne
--------------------------
arne wrote:
 > As we have mentioned several times, V2362 Cyg has a close
 > visual companion that was unimportant during outburst, but which
 > now influences the photometry.  I have psf-fit the Sonoita
 > Research Observatory images, and come up with the following
 > magnitudes/colors for the companion:
 >
 > Photometry psf-fitted, 6 measures/3 nights (070108-070110)
 >    star        V     B-V    V-Rc   Rc-Ic
 > companion   15.325  0.866  0.431  0.484
 >               0.024  0.070  0.047  0.047
 >
 > Since V2362 Cyg is currently about V=13.8, this means that
 > including the companion will make the total magnitude brighter
 > by about 0.2mags at V.  The companion is 5arcsec due west
 > of the nova.  Unless you have very good seeing and pixelization,
 > I recommend using a fairly large aperture for observing V2362 Cyg,
 > probably something in the 20arcsec diameter range.  Northern
 > observers should be able to observe V2362 Cyg in the early dawn,
 > and it would be good to continue monitoring this field until the
 > nova returns to quiescence.
 >