(vsnet-obs 2971) OIII emission in V705 Cas
Regarding the recent fading of V705 Cas and comments made by Mr. Kato on this star's current 'nebular phase', observers with an OIII or Lumicon UHC filter may want to try an interesting experiment. These filters will easily enhance this variable's brightness in relation to other field stars. By alternately moving the filter back and forth over the view, V705 Cas will appear to brighten and dim much like a stellar planetary nebula. It is a fascinating way to witness this star's OIII emissions.
Bob King, AAVSO observer
In response to Reinder Bouma's note re. V705 Cas.
I too have been puzzled by observations of V705 Cas posted to VSNET over the past few weeks or so, except that I have found it strange that some observers were reporting it so faint!
I can state with every confidence that the object which I have been monitoring is NOT GSC 4008.1363. I have been observing this nova since discovery in 1993 (300+ observations), and am absolutely confident that I am estimating the nova's brightness and not a field star. Both the TA and AAVSO charts identify the same object, which rules out any ID problem.
I have just made an observation of V705 Cas, taking great care (as usual) with the estimate. Although slightly fainter than last night, I still make it brighter than my Dutch friends. The observation is...
Jun 16.993 16-2 12.7 Class 1 40cm Seq. TA (Star 18 on the TA seq.(133 AAVSO) looks a little bright to me)
I take it that the magnitude of GSC 4008.1363 noted by Reinder in his message (approx. 12.5) was a combined one, as this star is obviously a double.
Concerning the message on the fading of V705 Cas: We observed this nova for about 20 nights continously during this winter with 1 meter telescope and a CCD. Our results indicate a continous fading of the nova: about 0.1 mag in the V band from 16/11/95 to 13/1/96, and about 0.2 mag in the I band from 25/8/95 till 13/1/96. Since we use just part of the ccd we cannot tell the exact valuses, however it seems consistent with the report.
Our observations also indicate a sinusoidal varioation of about 0.08 peak to peak mag in the I band and a bit less in the V filter The period is around 5.5 hours. (See I.A.U.C. No. 6234) This cannot explain the 1 mag difference between the various reports, but can add to the effect mentioned.
It also seems that the variation weakened during our observations, and it may fit to a fading of the white dwarf which causes less reflected light from its companion.
V705 Css fading page
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