Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 1603

GRB021004: restart of optical decay
2002-10-07T23:10:09Z (22 years ago)
Nicola Masetti at IASF,CNR,Bologna <>
N. Masetti, G. Pizzichini (IASF/CNR, Bologna), C. Bartolini, A. Guarnieri,
A. Piccioni, E. Maiorano, A. Simoncelli (Dip. Astronomia, Univ. of
Bologna) and A. De Blasi (INAF - Astron. Obs. of Bologna) report:

"On 2002 October 7 we have imaged the optical counterpart (Fox et al., 
GCN #1564) of GRB021004 (=H2380; GCN #1565) in the R band with the
1.52-m Loiano telescope (plus BFOSC) of the Astronomical Observatory of
Bologna. Our 30-minutes observation, which started at 18:45 UT, was 
carried out under poor seeing conditions (the seeing was ~3 arcsec).

Using the R-magnitude calibration of Henden et al. (GCN #1583), we find 
the optical afterglow of GRB021004 at R = 20.4 +- 0.1.
Therefore, the decline seems to have started again after the halt remarked
by Stanek et al. (GCN #1598); this is suggestive of a step-like decay
behaviour similar to that displayed by GRB000301c (Masetti et al., 2000,
A&A, 359, L23).

This message is quotable.".

[GCN OPS NOTE (07oct02):  This Circular was received at 21:46 UT,
but was delayed due to a change in the submittor's vetted address.]
Looking for U.S. government information and services? Visit