[vsnet-sdor 10] Re: HD 5980 rapid fading

[Taichi Kato <tkato>]

   Forwarded message from Dr. Koenigsberger is attached.  Please keep
a close eye on this object!

Date: Wed, 18 Oct 2000 14:51:30 -0500 (CDT)
From: Gloria Koenigsberger <gloria@astroscu.unam.mx>
Subject: Re: [vsnet-sdor 9] HD 5980 rapid fading

Dear Dr. Kato,

Luis Corral kindly sent me the message he received from you, regarding
the rapid fading of HD 5980.  I am very interested in this object, since
I am convinced that there will be another eruptive event in the near
future.  In the case of the data you sent, however, I have calculated
the orbital phases using the ephemerides P=19.266 and T_0=2443158.7,
and find that your observations correspond to the orbital phases between
0.2 and 0.4, which coincide (at 0.36) with the eclipse of Star A (the LBV/eruptor)
by Star B (presumably the original WR star), although a drop by 0.7mag
does seem a LARGE drop for visual magnitudes; I don't have my data here,
but I think that the usual amplitude of the light curve used to be around
0.3 mag.  I would very much appreciate
it if you could keep me posted on HD 5980's behavior, particularly
because we have submitted a proposal for observations with HST, and
any major change in its flux levels would affect  the exposure time
calculations, in case the proposal is approved.  Furthermore, it would
be very interesting to know if the short-period photometric oscillations
reported by Sterken and Breysacher (1997, A&A 328, 269), which have
a period of ~0.25 day, are still present.  Data such as you are acquiring
are extremely valuable, and I thank you for sharing them with the
community.

With best regards,
Gloria Koenigsberger


------------- Begin Forwarded Message -------------

Date: Wed, 18 Oct 2000 23:55:12 +0900 (JST)
From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
To: vsnet-ecl@kusastro.kyoto-u.ac.jp, vsnet-sdor@kusastro.kyoto-u.ac.jp
X-Distribute: distribute [version 2.1 (Alpha) patchlevel=24]
Subject: [vsnet-sdor 9] HD 5980 rapid fading

HD 5980 rapid fading

  YYYYMMDD(UT)   mag  observer
  20001015.776   107  (A. Pearce)
  20001016.787   110  (A. Pearce)
  20001017.806   114  (A. Pearce)

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