FIRE IN THE SKY ASTRONOMICAL OBSERVATORY
Here is an updated image of SN1998ar. 1. ST-6, G-11 at F6.3 2.Date: 4-24-98 at 2:33:19 UTC 3. Raw ccd magnitude:15.84Observer Jim Wentworth (fire in the sky astronomical observatory)
Some background data on SN1998aq from Hitoshi Yamaoka
Dear SN fans,
Dr. Rodrigues, M1 group, Spain, has pointed out the confusion in identification of SN 1998ar in NGC 2916. I have checked his image and I perfectly agree with him. I guess it is necessary for those who have observed this SN to check out whether the observed star was truely SN or not.
I have measured the locations of point-like sources around NGC 2916 with DSS-1 image and 5 GSC stars. Belows are the results, adding the position of SN 1998ar reported on IAUC 6877.
R. A. (2000.0) Decl. offset from core
Core of NGC 2916 9h34m57s.69 +21o42'18".8 --------
Star A 9h34m57s.88 +21o42'30".7 2"E, 12"N
Star B 9h34m57s.08 +21o42'54".5 8"W, 32"N
SN 1998ar 9h34m58s.86 +21o42'57".5 17"E, 39"N
Star A seems to be a foreground star. The magnitude of this star is
estimated as 15.5 mag or so on DSS1 image. Besides, Star B looks like
a condensation (bright region) of the host galaxy. It is about 16 mag
or so on the same image.
I have also checked the image taken by Dr. Wentworth, which can be accessed at http://www.RochesterAstronomy.org/snimages/sn98ar1.html . It was taken on Apr 24.1UT (its caption was referred), which time is consistent to the time of magnitude reported by himself on vsnet as 15.35C. His image has clearly shown Star A and Star B, and stellar-looking knot exists near the location of SN 1998ar (Star C). Star C seems to be dimmer than Star B, and comparing GSC 14.8 mag star and fainter neighbouring stars, its magnitude is about 1.5 mag dimmer than GSC 14.8 mag star; which tells that SN was about 16.3 mag. However, on the DSS image, there are the blobby knots near to the location of SN. Star C can be the integrated spot of these blobs and SN, so this magnitude should be taken as an upper limit.
This discrepancy can be due to mis-identification of SN. Could the observers of this SN check the images and the identifications?
Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp