[vsnet-chat 786] Re: 1998T (ISN)

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

Dear Supernova observers,

Dr. Howerton wrote:

>There is some question as to whether my visual observations of SN 1998T
>in IC 694 are of the correct object.  My software (Guide 6.0) shows NGC
>3690 to be the larger, elongated, northeastern galaxy; IC 694 is the
>smaller, nearly circular, and southwestern galaxy.  The image from the
>ISN site marking the supernova seemed to point to a bright spot in the
>southwestern galaxy.

As I noted on isn_chat or other places (or I have mis-posted?), IC 694
is the eastern galaxy of Arp299 complex. Please check at:
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/SNe/sn1998t.html , and
http://vsnet.ggw.org/asras/snimages/sn1998t.html .

The ISN image was pointed to the NGC 3690 core (which is
undeterminable, though), not to SN 1998T. It has removed from the 
page, now.

Many galaxy catalogs (including Arp original catalog too!) are
confusing about the identifications of these galaxies. RC3 takes the
western one as IC 694. I do not have Guide 6.0, but it seems that the
identification is reverse. 

The identification of these two are by Wynn-Williams (1991), ApJ, 377,
426, which was refered by the checker on IAUC, Dr. A. Filippenko. 

>The object I have been studying is a stellar object which lies in the
>northern half of the southwestern galaxy.  Archived images I have pulled
>off the web do show a number of stellar objects in northern half of this
>galaxy.

It should be the knot C of NGC 3690 (see above reference paper). But if
the variability you noticed is real, it can be the other supernova. 
This galaxy complex have produced many supernovae in these 10 years. 
The confirmation is urgently needed.

Best wishes,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

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