[vsnet-alert 9978] V635 Cas = 4U 0115+63 X-ray outburst

[Taichi Kato]

   V635 Cas = 4U 0115+63 is undergoing an X-ray outburst.

cf.
http://swift.gsfc.nasa.gov/docs/swift/results/transients/weak/4U0115p634/

   The reported optical brightening in R (by ~0.8 mag) is not very
apparent in recent visual observations.  V-band CCD observations would
clarify the nature of apparent color-dependent behavior.

  YYYYMMDD(UT)   mag  observer
  20080201.899   154  (Gary Poyner)
  20080208.778   154  (Gary Poyner)
  20080209.792   155  (Gary Poyner)
  20080210.806   154  (Gary Poyner)
  20080211.801  <151  (Gary Poyner)
  20080213.822  <151  (Gary Poyner)
  20080216.808  <151  (Gary Poyner)
  20080217.805  <151  (Gary Poyner)
  20080218.812  <146  (Gary Poyner)
  20080224.873   155  (Gary Poyner)
  20080226.798   154  (Gary Poyner)
  20080304.805   154  (Gary Poyner)
  20080309.835   154  (Gary Poyner)

   The object underwent several optical outbursts, notably in 1999 reaching
mag 14.5, but remained less active in recent years, including the 2004
September event (see below).

===

ATEL #1427                                                           ATEL #1427

Title:          Optical activity of 4U 0115+63
Author: V.Larionov (Astronomical Institute of St.Petersburg University,Russia),
                A.Arkharov (Pulkovo Observatory, Russia)
Queries:        vlar at astro.spbu.ru
Posted: 17 Mar 2008;  4:16  UT
Subjects:       Infra-Red, Optical, X-ray, Request for Observations, Neutron
                Stars, Transients

Recent high-energy observations (ATEL#1426) report the onset of a new
X-ray outburst of the binary X-ray pulsar 4U 0115+63. Our optical and NIR
monitoring results show remarkable similarity of its current behavior to
that observed during previous major outburst of 2004 September (see Reig,
Larionov, Negueruela et al., 2007, A&A, 462, 1081), in the sense that the
X-ray outburst occurs when optical level is close to its maximum (currently
R~13.6), following several months of enhanced activity. That kind of behavior
supports the model of decretion disc model, as suggested by Reig et al.
A part of our recent R-band light curve can be uploaded from ftp://observ.astro.spbu.ru/uploads/vlar
/4u0115/4u0115.eps
Observations in all energy ranges are highly desirable.