Central Bureau for Astronomical Telegrams
IAUC 4959: 1990B; 1990C
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Read IAUC 4960
Circular No. 4959
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
SUPERNOVA 1990B IN NGC 4568
N. Suntzeff, Cerro Tololo Interamerican Observatory, reports:
"Preliminary CCD photometry of SN 1990B obtained at the CTIO 0.9-m
telescope by M. Perez and L. Wells gives: Jan. 24.33 UT, V= 16.06,
B = 17.67; 25.36, 16.19, 17.75. According to M. M. Phillips,
spectrophotometry at the CTIO 1.5-m by M.-T. Ruiz indicates that SN
1990B was at this time roughly one week past maximum. From the few
type Ib supernovae that have been measured in B and V, one would expect
an intrinsic color B-V = +0.7 one week after maximum (Phillips and
Leibundgut, private communication), implying a reddening of 0.9 in
E(B-V). This is consistent with the very red continuum colors and
strong Na D absorption reported by Filippenko (IAUC 4953) and seen in
the CTIO spectrophotmetry."
N. Panagia, Space Telescope Science Institute; and A. Cassatella,
R. Gonzalez-Riestra, A. Talavera and W. Wamsteker, ESA IUE Observatory,
communicate: "SN 1990B was observed with the IUE long-wavelength camera
(190-320 nm) on Jan. 27.333 UT (120 min) and Feb. 4.324 (189 min).
No signal was detected at the coordinates provided by Dopita and Ryder
(IAUC 4953). The lack of detection provides an upper limit to the
supernova flux around 295 nm of about 1.4 x 10**(-15) erg cm-2 s-1 A-1.
This is lower by a factor of about 80 than the flux of 5.4 x 10**-(14)
erg cm-2 s-1 A-1 observed at the maximum of the type Ia supernova 1981B
in NGC 4536 after allowance for a 1.5 times greater distance to NGC 4536.
This result confirms SN 1990B as a type Ib supernova. Our SN 1990B
upper limit is also lower by about a factor of 5 than the expected flux
at maximum estimated by scaling the flux of the prototype type Ib
supernova 1983N in M83, assuming equal reddening and taking into account
a 2.5-mag difference in distance modulus. We conclude that either
SN 1990B is more heavily reddened than SN 1983N (at least 1 mag of
additional visual extinction), or on Jan. 27 SN 1990B was already a
couple of weeks past ultraviolet maximum."
SUPERNOVA 1990C IN ANONYMOUS GALAXY
C. Pollas, Observatoire de la Cote d'Azur, remarks that the offset
of this object (IAUC 4950) should be 3" east from the galaxy's nucleus.
R. P. Kirshner, Center for Astrophysics, reports that the object was
observed with the Multiple Mirror Telescope on Jan. 30 by J. P. Huchra,
who finds it to be a faint compact H II region with a redshift near
0.018. Although the object is not on the Palomar Sky Survey, it is
evidently not a supernova.
1990 February 7 (4959) Gareth V. Williams
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