From sullivan@wco.com Wed Mar 18 15:51:56 1998
Date: Fri, 13 Mar 1998 18:07:56 -0800 (PST)
From: Philip Sullivan
To: docents@vmoa.kenwood.ca.us
Subject: SN 1998S project
Some of you already know about supernova 1998S in NGC 3877 in Ursa Major.
This is the brightest SN in over a year and is well placed for observation
in the evening (17 arcmin directly south of Chi Urae Majoris). The
supernova was discovered Mar.3 at about 15th mag and is now approximately
mag 12, well within the reach of medium sized amateur telescopes.
1998S is a type II supernova (core collapse of single evolved star). Type
II's fade quite slowly and frequently rebrighten after their initial fading.
I believe that making a visual light curve of SN 1998S would be an very
interesting project for the Furgeson observatory docents (SCAS, VMAA). With
the 40" we should be able to get good estimates down to 15th mag (the limit
of the charts) as the SN gets fainter. Because the SN is right on the edge
of the galaxy's disk, it is difficult to do CCD (or PEP) photometry. It's
easier for the eye to ignore the background.
In a day or two, the moon will no longer interfere with observations. I
intend to do this project myself and invite any who are interested to
participate, either with me or on their own. Please let me know if you are
interested. I will email you the AAVSO chart with comparison stars down to
mag 15, as well as my most recent CCD image of the supernova. The chart can
be obtained directly from the AAVSO ftp site: ftp.aavso.org in the
pub/charts/uma directory.
Phil Sullivan
From sullivan@wco.com Wed Mar 18 15:13:52 1998
Date: Wed, 11 Mar 1998 18:40:13 -0800 (PST)
From: Philip Sullivan
To: rjw@alembic.com
Ron,
I've attached a better, and larger scale image of
SN 1998S (5.2KB) which I took on
the night of Mar. 8-9. I think following the light curve of 1998S would be
a nice project for the docents. In case anyone is interested in doing this,
I've attached a chart sequence complied by the Norwegian variable star
group. The information for the sequence stars is below. BTW, star number 1
is Chi Ursa Majoris.
Phil
Download Zipped .jpg and .fit image (42KB).
Download FITS image (uncompressed 132.5KB).
[Compiled by Bjorn H. Granslo (last update 1998 March 11)]
Below follows a list of field and sequence stars located within ~20'
from SN 1998S in NGC 3877:
-----------------------------------------------------------------------
Ident Star Name R.A. (2000.0) Decl. V-mag. B-V Ref. Notes
-----------------------------------------------------------------------
h m s o ' "
1 HIP 57399 11 46 03.0 +47 46 46 3.69 +1.18 H Sp. K0III
2 HIP 57349 11 45 31.0 +47 40 03 8.06 +0.62 H Sp. G2V
3 HIP 57385 11 45 55.5 +47 32 51 10.00 +0.78 H Sp. K0
4 TYC 3452-1157 11 47 12.9 +47 47 15 10.4 +0.6 T
5 TIC 3452-1079 11 47 39.9 +47 32 41 11.20: .... TI (b-r)=+0.5
6 TIC 3452-1149 11 45 44.9 +47 47 42 11.8 .... TI
7 GSC 3452-0905 11 47 09.0 +47 23 34 11.9 : .... G1
8 GSC 3452-1238 11 45 26.8 +47 48 32 12.2 : .... G2 (b-r)=+0.7
x GSC 3452-1101 11 45 35.6 +47 33 12 12.5 : .... G2 (b-r)=+1.1
y GSC 3452-1061 11 46 29.2 +47 31 09 12.6 : .... G2 (b-r)=+0.2
A GSC 3452-1170 11 46 20.1 +47 35 32 12.6 : .... G2 (b-r)=-0.3
B GSC 3452-1091 11 45 41.5 +47 32 47 13.2 : .... G2 (b-r)=+0.6
C GSC 3452-0978 11 45 30.1 +47 26 41 13.8 : .... G2 (b-r)=+1.1
D GSC 3452-0997 11 46 38.0 +47 27 36 14.5 : .... G1
E GSC 3452-0977 11 45 34.8 +47 26 49 15.0 : .... G1 (b-r)=+1.6
-----------------------------------------------------------------------
Supernova viewed with 40 inch.
Following is original message and images
From sullivan@wco.com Thu Mar 5 11:36:47 1998
Date: Thu, 5 Mar 1998 10:18:06 -0800 (PST)
From: Philip Sullivan
To: rjw@alembic.com
Subject: new bright supernova
Ron,
Here's a quickie first image of SN 1998S (jpeg 3KB).
It was reported Feb. 4 and
brightened from 15th to 13th mag in one day. It's the brightest SN to
appear in over a year and should be easily observable in medium sized
amateur telescopes. The SN is in NGC 3877, an 11.5 mag galaxy just south of
the bowel of UMa, about 17 arcmin north of Chi UMa.
(I went crazy trying to get a good image last night. I couldn't position
the galaxy anywhere in the field to eliminated the streak of scattered light
from Chi UMa (the streak of light above the galaxy). I'm going to change a
few things around in the configuation of the camera and focal reducer. I'll
try for a deeper and cleaner image on the next clear night. This was a two
minute exposure. As usual, the FITS (132KB) image
looks much better in my software than the JPEG.)
Phil
download 68KB .ZIP file of both jpeg and fits images.