[vsnet-alert 2006] Re: "SN 1998di", new He CV

[Yamaoka Hitoshi <yamaoka@rc.kyushu-u.ac.jp>]

Dear vsnet-ers,

> Using USNO stars, this stellar object was about 17.0-17.5 magnitude
> at 1991 Sep. 2. (I will examine it more presicely again. )  

I have overestimated the magnitude because I have used saturated stars
as references.  And now I have gotten dimmer USNO stars. 

At a grance, this starlike point seems about the same magnitude as the
star (a) on 19h24m39s.41,+59o41'57".60, and slightly dimmer than the
star (b) on 19h24m40s.79,+59o41'34".48, and slightly brighter than the
star (c) on 19h24m49s.87,+59o41'42".33. The magnitudes (USNO V
equivalent) of these stars are 19.25 (a), 19.28 (b), and 19.26 (c),
respectingly.  This implys that the stellar magnitude is around 19.25
mag or so. 

However, the contamination of the background galaxy is fatally great.
The substraction of galaxy (somehow assumed surface) is necessary for
further preciseness.  The contour map of this region shows at a grance
that this stellar image could not brighter than 20.5 mag or so.  

Other independent estimate is urged. 

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

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