Central Bureau for Astronomical Telegrams
IAUC 6848: N Sgr 1998; GRB 970508
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Circular No. 6848
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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NOVA SAGITTARII 1998
M. Della Valle, Astronomy Department, Padua University; and A.
Pizzella and M. Bernardi, European Southern Observatory, report:
"Preliminary analysis of a spectrum of N Sgr 1998 (IAUC 6846, 6847),
obtained at La Silla with the 1.54-m Danish telescope (+ Danish
Faint Object Spectrograph and Camera; range 370-760 nm, resolution
about 1 nm) on Mar. 24.3 UT, confirms this object to be a galactic
nova caught during an early stage. The continuum appears dominated
by emission lines of the Balmer series, flanked by weak P-Cyg
profiles, Fe II (multiplets 42, 48, 49, 74, 224), and N II and Na I
lines. The massive presence of iron and the relatively slow faint
expansion velocities inferred from the FWHMs of H-alpha and H-beta
(1600 and 1800 km/s, respectively) suggest that this nova may
belong to the Fe II class (see Williams 1992, A.J. 104, 725)."
Visual magnitude estimates: Mar. 23.687 UT, 7.4 (A. F. Jones,
Nelson, New Zealand); 24.12, 8.3 (L. Kiss, Szeged, Hungary); 24.139,
8.1 (K. Hornoch, Lelekovice, Czech Republic); 24.183, 8.5 (P.
Schmeer, Bischmisheim, Germany); 24.21, 7.6 (J. M. Trigo,
Benicassim, Spain).
GRB 970508
A. J. Castro-Tirado and J. Gorosabel, Laboratorio de
Astrofisica Espacial y Fisica Fundamental, Madrid; T. Galama and P.
Groot, University of Amsterdam; J. van Paradijs, University of
Amsterdam and University of Alabama at Hunstville; and C.
Kouveliotou, Universities Space Research Association, report: "R-
band images have been obtained by J. H. Telting, B. Garcia-Lorenzo,
and L. Jones (Isaac Newton Group Telescopes) with the 4.2-m
William Herschel Telescope on La Palma on Mar. 20/21. At the same
position of the optical counterpart to GRB 970508 reported by Bond
(IAUC 6654), the co-added image (13700 s) reveals an object 5.4 mag
fainter: R = 25.20 +/- 0.25 (based on the secondary standards
given by Sokolov et al. 1998, at
http://xxx.lanl.gov/abs/astro-ph/?9802341). This is about 1.0 mag
brighter than expected from the extrapolation of the power-law
decline (R = 26.18 +/- 0.09), suggesting that the optical light is
dominated by the host galaxy. Assuming its location at z = 0.8
(Metzger et al. 1997, Nature 387, 879), this corresponds to an
absolute blue magnitude of -17.9 +/- 0.5, placing the object below
the knee of the galaxy luminosity function."
(C) Copyright 1998 CBAT
1998 March 24 (6848) Daniel W. E. Green
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