[vsnet-gcvs 244] Re: IL Lup = 4U1543-47 bright outburst!

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

Re: IL Lup = 4U1543-47 bright outburst!

> 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). 

   This star 'X' is not particularly red, as inferred from the Tycho-2
photometry.  Given the extinction for IL Lup, red bands would be more
efficient in eliminating the contamination from the this star.

> 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.

   Use short exposure times (to avoid saturation from the nearby star),
and use PSF fitting when possible.  At this separation, a small aperture
also would yield acceptable results.  [In case anyone can send FITS images,
we will be able to make PSF photometry].

   By the way, what is HL Lup?  Is this object identical with IL Lup??

Regards,
Taichi Kato

VSNET Home Page

Return to Daisaku Nogami

---

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