Central Bureau for Astronomical Telegrams
IAUC 6725: 1997de; 1997dd; GRB 970815
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Circular No. 6725
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1997de IN NGC 6769
Alexander Wassilieff, Palmerston North, New Zealand, reports
his discovery, on two CCD images taken with a 0.36-m f/4 reflector
(+ SBIG ST-7 camera) on Aug. 27, of an apparent supernova (mag
about 18.2) located 14".5 west and 20".6 north of the center of NGC
6769 (R.A. = 19h18m.4, Decl. = -60o31', equinox 2000.0). The star
does not appear on a similar image taken on 1994 July 9, nor does
it appear on the Digital Sky Survey. B. Schmidt, Mount Stromlo and
Siding Spring Observatories, reports via R. Evans that Brendan
Downs (at Camp Duckadang, Queensland) independently found SN 1997de
with a 0.31-m telescope (+ CCD) on Aug. 27.7, the offset noted as
16" west and 22" north of the center of NGC 6769.
N. Suntzeff, Cerro Tololo Interamerican Observatory (CTIO),
reports that spectrophotometry (range 320-900 nm; resolution 900)
was obtained by J. Maza on Aug. 28.0 UT with the CTIO 4-m
telescope. M. Phillips and Suntzeff find the spectrum of SN 1997de
to be that of a type-Ia event, about 4 weeks after maximum. There
is significant Na I absorption (0.23 nm) at 3900 km/s (at the
redshift of the host galaxy).
SUPERNOVA 1997dd IN NGC 6060
Suntzeff also reports that spectrophotometry (obtained as
above) of SN 1997dd leads Phillips and himself to deduce this
object to be a peculiar type-II supernova. H-alpha is clearly
present but weak, and the redward emission is particularly weak.
H-beta is extremely weak. Strong Ca II absorption at 390 and 840
nm is present, as is the absorption feature (Na I/He) at 580 nm.
The spectrum appears to be intermediate between types II-P and Ib,
and it is very similar to the spectrum SN 1987K, 7-9 days after
maximum. SN 1997dd is thus expected to evolve rapidly into a type-
Ib/c supernova.
GRB 970815
M. T. Adams, M. Ward, F. Ma, A. Howell, L. Wang, and J. C.
Wheeler, McDonald Observatory, report: "The field of GRB 970815
was observed with the primary-focus camera on the McDonald
Observatory 0.76-m telescope. The images cover a field 46' x 46',
centered on the RXTE burst position. The limiting magnitudes of
the images are: Aug. 17.2 UT, R = 20.2, I = 19.9; 21.2, R = 20.4,
I = 20.5; 25.2, I = 21; and 27.2, V = 21, I = 21. No objects
brighter than R = 19.0 and I = 19.5 showed variability > 0.4 mag in
the entire field during these observations."
(C) Copyright 1997 CBAT
1997 August 28 (6725) Daniel W. E. Green
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