[vsnet-alert 9408] V5558 Sgr: rapid decline, spectrum at maximum by Fujii, comparison with V723 Cas

[Taichi Kato]

   As reported by several observers, V5558 Sgr has undergone
a rapid decline immediately following the recent brightness
peak.

   For comparison, the peak phase of V723 Cas lasted for 6 days,
followed by 1 mag within 1 day.  The peak phase of V5558 Sgr
lasted for ~4 days.

   A spectrum taken by Fujii-san during the peak maximum (July 11) 
resembles that of V723 Cas during the corresponding phase.

http://www1.harenet.ne.jp/~aikow/etc/v5558_sgr_20070711.gif
(weaker Balmer emission lines; Fe II emission lines almost
disappeared; moderately reddened F-type continuum, presumably
supergiant-like - more detailed description will be reported
after Fujii-san's inspection of the data)

   The spectral development of V723 Cas during this phase was
reported by Iijima et al. A&A 338, 1006 (1998).  We can expect
similar rapid evolution at this stage.

  YYYYMMDD(UT)   mag  observer
  20070702.542  7.57y  (Kazuhiro Nakajima)
  20070702.551  7.34V  (Kazuhiro Nakajima)
  20070702.564  6.76Rc  (Kazuhiro Nakajima)
  20070702.566  8.00B  (Kazuhiro Nakajima)
  20070703.129  7.443C  (Pi of the Sky)
  20070703.460    77  (Peter F. Williams)
  20070704.134  7.416C  (Pi of the Sky)
  20070705.560    71  (A. Kamiya)
  20070705.567  7.27V  (Kazuhiro Nakajima)
  20070705.572  6.69Rc  (Kazuhiro Nakajima)
  20070705.583  8.00B  (Kazuhiro Nakajima)
  20070705.585  7.39y  (Kazuhiro Nakajima)
  20070705.633  6.03Ic  (Hiroyuki Maehara)
  20070705.634  6.70Rc  (Hiroyuki Maehara)
  20070705.634  7.22V  (Hiroyuki Maehara)
  20070705.637  8.03B  (Hiroyuki Maehara)
  20070705.638  7.23y  (Hiroyuki Maehara)
  20070706.390    75  (Peter F. Williams)
  20070706.926    72  (Wolfgang Kriebel)
  20070707.422    73  (Peter F. Williams)
  20070707.567    71  (Hitomi Ishii)
  20070707.647    71  (Atsuko Takahashi)
  20070708.135  6.847C  (Pi of the Sky)
  20070708.344  6.75V  (Mike Linnolt)
  20070708.560    69  (Hitomi Ishii)
  20070708.601    69  (Atsuko Takahashi)
  20070709.135  6.668C  (Pi of the Sky)
  20070709.553    68  (Hitomi Ishii)
  20070709.560    67  (Atsuko Takahashi)
  20070709.895    66  (Jose Ripero)
  20070710.917    65  (Jose Ripero)
  20070711.134  6.719C  (Pi of the Sky)
  20070711.376    71  (Peter F. Williams)
  20070711.625    68  (Yutaka Maeda)
  20070711.909    67  (Jose Ripero)
  20070712.136  6.625C  (Pi of the Sky)
  20070712.494    71  (Peter F. Williams)
  20070712.895    72  (Jose Ripero)
  20070712.969    75  (Gary Poyner)