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Date: Sat, 17 Apr 93 03:38:35 JST
From: Hitoshi Yamaoka <g78261a@kyu-cc.cc.kyushu-u.ac.jp>
Subject: visual estimate
Newsgroups: sci.astro
From: sheaffer@netcom.com (Robert Sheaffer)
Subject: Re: Observations of SN 1993J - Mag approx 10.9
Organization: Netcom - Online Communication Services (408 241-9760 guest)
Date: Fri, 16 Apr 1993 04:51:55 GMT
Once again I observed SN1993J using a 12.5" reflector, under suburban
skies, 16 April 04:20 UT. It appears essentially the same brightness
as two nights ago, perhaps marginally fainter. I would estimate
it as approx. 1/2 magnitude brighter than comparison star A (11.4), which
would make it 10.9. Comparison star X (which is actually a double of
two stars of very nearly equal brightness) is given as 10.5 in the SAO,
which presumably is the combined magnitude. SN is well below this
brightness, but is a little brighter than either singly.
One of the comparison stars - I believe it is D - must have an invalid
magnitude on the charts, as it is clearly brighter than "advertised"
(12.4); it must be approx 10.5, which is evident in the photo GIF from
the University of Iowa (in which NGC 3031 is mislabelled "M31" instead
of M81). Perhaps this star is variable. This star is actually brighter
than the SN by a few tenths of a magnitude.
--
Robert Sheaffer - Scepticus Maximus - sheaffer@netcom.com
Past Chairman, The Bay Area Skeptics - for whom I speak only when authorized!
"Marxism and feminism are one and that one is Marxism"
- Heidi Hartmann and Amy Bridges,
quoted by Catharine MacKinnon above the first chapter
of her "Toward a Feminist Theory of the State"
--- 8< --- 8< --- 8< --- 8< --- 8< ---
From: wgd@se.houston.geoquest.slb.com (Bill Dillon)
Newsgroups: sci.astro
Subject: Re: A question-what Mag.is SN1993J.??
Date: 15 Apr 93 14:31:13 GMT
Organization: GeoQuest Systems Inc. Houston
Nntp-Posting-Host: brahms.se.houston.geoquest.slb.com
In article <C5Hp8J.4It@cs.dal.ca> andromed@Hail.ATM.Dal.Ca (Mike Boschat) writes:
>hello;
>
> Just a quick question....how come observations of supernova
>1993J are so varied in magnitude..? I've so far seen it posted
>from 11 Mv to 10.6 Mv, now I hear its back to 11 Mv..what the
>heck is it..?
> Mike Boschat
Hello Mike!
I estimated SN 1993J's magnitude at 10.6 early this morning (April 15.18) using
comparison stars of magnitudes 10.7 and 10.5 from the Supernova search charts
by Thompson and Bryan. The observation was made using a 28 cm schmidt-
cassegrain telescope.
It's interesting that this born-again supernova is nearly as bright as its
maximum in late March!
As to the scatter, people may be using different magnitude estimates for the
comparison stars, and there is some background light from the galaxy that must
make reducing CCD observations a little tricky. Finally, the supernova itself
may be changing on short time scales.
Regards,
Bill
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