[vsnet-alert 7412] IL Lup = 4U1543-47 bright outburst!

["Berto Monard" <LAGMonar@csir.co.za>]

Dear readers and CCD observers of the South,

I would like to stress that IL Lupi is located very close to a brigth
neighbouring star 'X' (approx 11.5R). Unless a large magnification can
be used (+ good tracking), it would be difficult to separate them for
photometric measurements especially with automated software.
IL Lup is located to the NW of its bright neighbour.

I have done a two hour run last night on IL Lup and the images show IL
Lup noticeably brighter than at quiescense. 

Photometric data processing show no noticeable brightness changes of
the combined area (IL Lup + X), something that could be expected in the
abscense of large flares.

For whatever reason, USNO A2.0 has no data on IL Lup or its neighbour.
Possibly this X star is very red as most of the stars in the
neighbourhood or they are reddened by the interstellar extinction
(A_V=2.1 mag). 

As Il Lup must be emitting much more blue light (accretion flow) I
would advice to take measures preferably in the B band. Despite the much
lower S/N some brightness evolution might be derived.


Regards,

Berto Monard
Bronberg Observatory
near Pretoria 

PS I will try to remeasure the data later today, using small area
circles... 
  

>>> Taichi Kato <tkato@kusastro.kyoto-u.ac.jp> 06/20/02 06:29AM >>>
Re: IL Lup = 4U1543-47 bright outburst!

   According to Chen et al. (1997) ApJ 491, 312, IL Lup underwent
three
historical X-ray outbursts (1971 August, 1983 August, 1992 April).

   The 1971 outburst reached 2.1 Crab, and the X-ray light curve
resembled those of "classical" X-ray novae (fast rise, slow
exponential
decay).  The 1983 outburst reached 10 Crab.  Although the fading
part of this outburst was not well observed, the data suggest that
the X-ray light curve was of similar type.  However, the 1992 outburst
(1.04 Crab), the decay time-scale was only 1.6 d, indicating that
this outburst had different characters from the previous outbursts
(more resembling V4641 Sgr outbursts??)

   During the 1983 outburst, optical observation confirmed the
beightening to V=14.9.  The quiescent counterpart is reported
to have V=16.7.  The reported interstellar extioction (A_V=2.1 mag)
makes IL Lup a promosing target for CCD (red bands) observers.

Regards,
Taichi Kato

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp