Central Bureau for Astronomical Telegrams
IAUC 6723: GRB 970616; GRB 970815
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Circular No. 6723
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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GRB 970616
P. J. Groot and T. J. Galama, University of Amsterdam; K.
Hurley, University of California at Berkeley; and C. Kouveliotou,
Universities Space Research Association, on behalf of a larger
collaboration, report: "Keck II images of GRB 970616, taken on June
21.6 and July 11.6 UT (unfiltered) and July 1.6 (R-band), show that
the error box of the second ROSAT source, coinciding with the first
ASCA variable source (IAUC 6687, 6722), contains four objects with
(clockwise from north) magnitudes R = 24.8 +/- 0.15 (object A),
25.9 +/- 0.25 (B), 26.1 +/- 0.25 (C), 25.8 +/- 0.25 (D). For the
image, see http://www.astro.uva.nl/paulgr/grb/grb970616.html.
Located at the west and northeast edges, respectively, of the error
box are two brighter objects, at R = 23.2 +/- 0.1 (object E) and
21.7 +/- 0.1 (F). None of these sources shows variation > 0.3 mag.
Note also that the variability of the star reported by Galama et al.
on IAUC 6687 reflects incorrect filter information for the June
21.6 observation; it shows no variability exceeding 0.1 mag between
June 21 and July 11."
GRB 970815
Groot et al. also write: "Observations of the error box of GRB
970815 (IAUC 6718, 6722) with the 1-m JKT reflector at La Palma on
Aug. 16.10, 16.95, and 19.01 UT (V band) and the 3.5-m telescope at
Apache Point Observatory on Aug. 16.3 and 16.5 (Sloan g' band) show
no sources with variability > 0.25 mag for V < 21.5."
S. R. Kulkarni, S. C. Odewahn, and S. G. Djorgovski,
California Institute of Technology; D. A. Frail, National Radio
Astronomy Observatory; R. F. Goodrich, Keck Observatory; and L. M.
Maxfield, University of California at Berkeley, report: "We
observed the field of GRB 970815 in the Gunn i band using the CCD
camera at the Palomar 1.52-m (P60) telescope during about Aug.
18.19-18.35 UT. No statistically-significant variable sources
changing by > 0.3 mag over the 4-hr interval were found, down to
the limiting i-band magnitude of 20.5. Additional images were
obtained at the Keck-II 10-m telescope during Aug. 20.26-20.29,
reaching a limiting mag of I about 24-24.5. No significantly-
variable sources changing by > 0.5 mag over the period of 2 days
were found, down to the limit of the P60 data. Very Large Array
observations were made of the error box on Aug. 16.64, 17.10, and
21.13 at wavelengths of 6 and 3.6 cm. No reliable source
detections were made inside this region above 0.35 mJy."
(C) Copyright 1997 CBAT
1997 August 26 (6723) Daniel W. E. Green
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