Central Bureau for Astronomical Telegrams
IAUC 4334: 1987A
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Circular No. 4334
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-495-7244/7440/7444
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
The following provisional magnitudes were measured with the
Australian National University's 0.6-m reflector at Siding Spring
Observatory by J. Dawe and R. H. McNaught: Mar. 5.484 UT, V =
4.36, B-V = +1.15, U-B = + 1.48; 5.643, 4.39, +1.13, +1.38.
M. G. Pastoriza and T. Storlhi-Bergmann, Instituto de Fisica,
Porto Alegre, communicate: "Using the 1-m telescope and 2D-Frutti
detector at Cerro Tololo Interamerican Observatory, we observed
the spectral region from 370 to 700 nm at 0.5-nm resolution during
Feb. 27-Mar. 5. The general pattern of the spectrum is that of a
type II supernova like 1979C in M100, dominated by Balmer lines
with P-Cyg profiles blueshifted by different amounts, as follows:
1987 UT H alpha H beta H gamma H delta
Feb. 27.01 - 8.7 -16.7 - 4.6 -13.7 - 2.5 -11.9 - 3.7
28.01 - 6.6 -15.9 - 2.9 -12.1 - 1.4 -12.6 - 2.4 -12.5
Mar. 1.07 - 5.8 -15.4 - 1.7 -12.5 0.0 -10.4 - 2.1 -10.1
2.06 - 3.8 -14.6 - 1.9 -11.3 - 0.7 -10.6 - 1.9 -10.3
3.04 - 3.0 -14.0 - 1.4 -11.5 - 0.8 -10.4 - 2.2 - 9.7
4.02 - 3.5 -13.3 - 0.6 - 9.9 + 1.5 - 8.3 - 1.0 - 8.8
5.01 - 2.7 -14.7 0.0 - 9.0 + 1.7 - 9.2 - 1.8 - 8.8
The pairs of columns refer to emission and absorption, respectively,
and velocities are in units of 10**3 km/s. The observed expansion
velocities decreased by about 3000 km/s during the first three
days, leveling off on Mar. 4 and 5. Fe II 458.3 and 494.8 nm
emission lines were also observed. The 458.3/H gamma ratio increased
from 1 on Feb. 26 to 2 on Mar. 5. On Mar. 2 an absorption line
identified as Mg I 518.3 nm appeared, reaching half the depth of
H beta on Mar. 5. Another absorption feature developed on Mar. 5 that
could be He I 587.5 nm, Na I 589.0 nm or a blend of the two."
G. de Vaucouleurs, University of Texas, has also drawn attention
to the possibility (cf. IAUC 4329) that SN 1987A is a type IIp
object at premaximum halt. He adds: "The maximum may occur about
Mar. 20-25 at mag about 2.5. The corresponding absolute magnitude M about
-16.2 for an apparent LMC distance modulus of 18.7 (de Vaucouleurs
1980, PASP 92, 579) agrees closely with the mean of type IIp objects
(M about -16.1) on the short distance scale (de Vaucouleurs 1979,
Ap.J. 227, 754). For a long distance scale (H0 about 50 km s-1 Mpc-1)
to be correct SN 1987A would have to reach mag about 1.0 at maximum."
1987 March 7 (4334) Brian G. Marsden
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