Central Bureau for Astronomical Telegrams
IAUC 8403: PKS 0405-385; 2004ef; C/2004 Q1
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Circular No. 8403
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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PKS 0405-385
G. Cimo, S. Ellingsen, S. Carter, and P. McCulloch, University
of Tasmania; and D. Jauncey and J. Lovell, Australia Telescope
National Facility, CSIRO, write: "We have observed a new episode of
rapid variability in the flux density of the quasar PKS 0405-385 on
hourly time scales. VLBI observations with the Australian Long
Baseline Array at 2.2 GHz in Apr. 2004 revealed variations at a
level of 10 percent with a period of 2 hr superimposed on a mean
flux density of about 1.6 Jy. Observations at 6.7 GHz with the
University of Tasmania Ceduna 30-m radio telescope over 10 days in
August show that this variability currently continues. Since its
discovery in 1996 (IAUC 6418), PKS 0405-385 has shown episodic
periods of extremely fast (intra-hour) variability at centimeter
radio wavelengths due to interstellar scintillation. The source
has alternated between long periods (years) of quiescence and short
(a few months) periods of intense activity. The reasons for the
sudden change in behavior are not understood, and observations at
radio and other wavelengths during the current active phase are
encouraged."
SUPERNOVA 2004ef IN UGC 12158
G. Folatelli, Las Campanas Observatory, together with M. Hamuy
and N. Morrell, on behalf of the Carnegie Supernova Project, report
that two optical spectra (range 400-730 nm) of SN 2004ef (cf. IAUC
8399), taken by W. Krzeminski on Sept. 7.16 UT with the Las
Campanas 2.5-m du Pont telescope (+ Modular Spectrograph) and by J.
Maza and E. Treister on Sept. 8.18 with the 6.5-m Clay telescope (+
Boller & Chivens Spectrograph), reveal that this is a type-Ia
supernova, supported by the presence of Si II at 635.5, 413.0, and
597.2 nm and by S II at 545.4 and 564.0 nm. Similar spectral
features have been observed in spectra of the normal type-Ia
supernovae 1994D and 1999ee at 10 days before maximum, which
suggests an early phase for 2004ef. The minimum of the Si II
635.5-nm line yields high expansion velocities of 16200 and 14500
km/s on each night, respectively, assuming the NED host-galaxy
recession velocity of 9290 km/s. An upper limit of 0.05 nm is
given to the equivalent width of the interstellar Na I D line,
indicating a low reddening by dust in the host galaxy.
COMET C/2004 Q1 (TUCKER)
J. J. Gonzalez, Leon, Spain, reports visual total mag 12.9 and
coma diameter 1'.5 on Aug. 26.14 UT (0.20-m reflector).
(C) Copyright 2004 CBAT
2004 September 9 (8403) Daniel W. E. Green
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