SN 1998S in NGC 3877
SN 1998S in NGC 3877
(V-band CCD image taken at Ouda Station, observer Daisaku Nogami)
Dear VSNetters,
According to IAU Circular 6829, Supernova 1998S was detected in NGC 3877 on Mar. 3 UT by BAO Supernova Survey. It was about 15.2 mag (unfiltered) on the discovery frame, and then rised to 13.5 mag (also unfiltered) on Mar. 4.3 UT.
The location of SN 1998S is:
R.A. = 11h46m06s
Decl. = +47o29'.0 (2000.0)
which is 16" west and 46" south of the nucleus of the host galaxy. The spectroscopy shows featureless continuum but probably with a broad H-alpha emission, which indicates that this SN is of type-II in very early phase.
The location of SN 1998S is embedded on the host galaxy. So the photometry is rather difficult; but it is very challenging and the results should be very useful. Following Observations are greatly praisworthy.
Clear Skies, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp
Akimasa Nakamura (a-nakamu@mx2.nisiq.net) has forwarded the following prediscovery observation of SN 1998S, measured by him from a CCD image taken by K. Kawakami (Kochi University).
1998 Mar. 2.70 UT mag 16.0: instrument: 20.3cm(F6.3) Schmidt-Cassegrain + unfiltered CCD. exposure: 60 sec. comparison star: Hipparcos Nakamura comments the subtraction of the galaxy background was difficult. SN1998S 980302.70 160:C Nma+Kawakami
H/T comparison stars around SN1998S (including some Stroemgren measurements)
114533.7 +474014 (2000.0) V=8.065(4) b-y=0.394(2) m1=0.165(3) c1=0.306(4) beta=2.580(2) 114531.0 +474003 (2000.0) 807 0.61 TYC3452.1132.1 plx=9.2(5.5) (0.01 0.01) 114916.7 +474806 (2000.0) 899 0.99 TYC3452.1143.1 plx=-2.3(10.9) (0.02 0.03) 114916.7 +474806 (2000.0) 901H 0.99 HIP057650 plx=2.90(1.32) (0.02 0.03) 114555.5 +473250 (2000.0) 987 0.90 TYC3452.1093.1 plx=-1.1(18.5) (0.04 0.06) 114908.8 +473828 (2000.0) 1039 0.62 TYC3452.1288.1 plx=4.8(26.2) (0.05 0.06) 114711.2 +474655 (2000.0) V=10.481(-) b-y=0.343(-) m1=0.187(-) c1=0.445(-) beta=2.650(-) 114712.9 +474715 (2000.0) 1042 0.55 TYC3452.1157.1 plx=17.2(27.0) (0.07 0.08) 114355.3 +471744 (2000.0) 1053 0.56 TYC3452.728.1 plx=35.1(28.3) (0.06 0.07) 114358.2 +471136 (2000.0) 1055 0.28 TYC3452.511.1 plx=19.9(22.1) (0.06 0.07)
Supernovae Collegues:
A photometric sequence of comparison star magnitudes for use in securing magnitude estimations of SN1998S near the area of NGC 3877 is presented. The information is gleaned from "The Guide Star Photometric Catalog I."(Lasker et. al, ApJ., Volume 68, #1 "Supplement Series", September, 1988). The finder chart/area is designated P-169 (~2.7 degrees [+/-] away from the host galaxy [star A], in P.A. ~268 degrees [+/-], {almost due west from NGC 3877})(Note: The comparison star coordinates are in epoch 1950. GSC star numbers are also included, if you prefer to utilize epoch 2000.0 coordinates.
It might also be noteworthy to mention that the GSC rendered magnitudes in this instance are pretty close to the photometrically measured magnitudes found in data from the abovementioned work.
Star(GSC#) RA (1950.0) Dec V-Mag.* B-V ____________________________________________________________ A (3451:733) 11h27m10.8s 47d33'36" 8.89 0.96 B (3451:960) 11h26m48.8s 47d35'25" 11.21 0.61 C (3451:444) 11h26m50.9s 47d22'49" 12.49 0.70 D (3451:728) 11h27m48.3s 47d34'03" 13.78 0.59 E (3451:440) 11h26m58.6s 47d36'31" 15.11 0.45 ____________________________________________________________ * = no error values indicated in GSPC data are noted here.Best Regards,
Steve
Norwegian Astronomical Society - Variable Star Section
***** COMPARISON STARS FOR SUPERNOVA 1998S IN NGC 3877 *****
[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
-----------------------------------------------------------------------
Identifications are from TA E-Circular 1278 (capital letters) and
NAS.VSS (others). Positions are given to an accuracy of 0.1s in R.A.
and 1" in Decl. V-magnitudes followed by a colon (:) are uncertain.
Accurate photometry is currently available only for stars 1, 2 and 3.
Star 1 is Chi UMa. Star 5 appears to be double. References to positions
and magnitudes are H = Hipparcos Catalogue, T = Tycho Catalogue,
TI = Tycho Input Catalogue, G1 = Guide Star Catalogue, Ver. 1.1 [GSC]
(single entry), G2 = GSC (mean of two entries). Colour indices (b-r)
are based on the PPM USNO-A1.0 catalogue. The catalogues were accessed
via the VizieR service of CDS, and the compiler wish to thank CDS for
this service.
Yours sincerely,
Bjoern H. Granslo
(bgranslo@astro.uio.no)
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