BZ Cam: Some brightenings

T. Watanabe (VSOLJ) reported the brightening (13.5mag on February 9) of BZ Cam (VY Scl-type novalike variable), which had been undergoing the second historical fading (vsnet-alert 4162).

A short article submitted by I.L.Andronov

(vsnet-alert 4354)

Intermediate state of BZ Cam

I.L.Andronov (1,2), K.Gazeas (2), P.G.Niarchos (2)
1 Department of Astronomy, Odessa State University, Ukraine
2 Department of Astrophysics, Astronomy and Mechanics,
  Athens University, Greece

The star BZ Cam = 0623+71 was recently reported to be decreasing
in brightness by T. Watanabe ([vsnet 1965] BZ Cam preprint),
who observed the star declining from 12.3 (JD 24 51061.269)
to 13.9 (JD 51551.125). The characteristic time for this interval
is dt/dm=294+-7 days/mag.
   We have observed the star in V filter with the 40-cm telescope
of the Athens University observatory by using the ST-8 CCD camera
on March 6/7, 2000 (JD 24 51610.375-.491) during 3.5 hours. The
comparison star "4" was used (Henden and Honeycutt, 1996) with
   BZ Cam varied from 12.9 to 13.2, far either from the last value
13.9 observed by T.Watanabe or from the value 14.13+-0.03 expected
from continuation of the linear decline.
   Thus we conclude that the star is bright again, with an incline
much faster (<60 days) than the decline from the same magnitude
(~250 days assuming linear decrease).
   The previous observations of this star in 1991 have shown
the power law shape of the periodogram for fast variability:
S(f) ~ f^{-g} with a power index g=1.08+-.05 in U and 0.86+-0.04
in R (Shakhovskoy et al., 1992a) or 1.51+-0.13 (Patterson et al.,
1996). It is interesting to check, whether this parameter is
dependent on the mean brightness, as, e.g. in AM Her
(Shakhovskoy et al., 1992b). More details on the "red noise"
in cataclysmic variables may be found in Andronov (1999ab),
see also

Andronov I.L.: 1999a, "Red noise" from the accreting magnetic
  white dwarfs. - Astron. Soc. Pacif. Conf. Ser., v 169., 326-336.
Andronov I.L.: 1999b, "Wavelet analysis of the irregularly spaced
  time series".- in: "Self-Similar Systems", eds. V.B. Priezzhev,
  V.P. Spiridonov, Dubna, Russia, JINR, 1999, 57-70.,
Henden A.A., Honeycutt R.K: 1996, "Secondary photometric standards
  for northern nova-like cataclysmic variables", PASP, 107, 324-346.
Patterson J., Patino R., Thorstensen J.R., Harvey D., Skillman D.R.,
  Ringwald F.A.: 1996, "Periods and quasiperiods in the cataclysmic
  variable BZ Camelopardalis", AJ 111, 6, 2422-2430.
Shakhovskoy N.M., Efimov Yu.S., Andronov I.L., Kolesnikov S.V.:
  1992, BZ Camelopardalis = 0623+71 : The Cataclysmic Variable
  inside a Bow-Shock Nebula.- in: "Planetary Nebulae. Abstracts",
  Innsbruck, 1992, p.80; IAUSymp. 155, Kluwer, 1993, 407.
Shakhovskoy N.M., Kolesnikov S.V., Andronov I.L. : 1992b,
  "AM Herculis at the low state: The circular polarization
  disappeared", in: 'Magnetism in Stars', Moscow, Nauka Publ.,
  p. 148-154.

T. Watanabe reported a brightening (12.6mag) on March 8 and estimate the increasing speed is 1.1mag/33days = 30 days/mag (from 13.7 to 12.6, assuming linear increase) (vsnet-alert 4361).

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