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GCN Circular 315

Subject
GRB990510
Date
1999-05-11T12:56:04Z (25 years ago)
From
Brian Schmidt at Australian Nat. U. <brian@mso.anu.edu.au>
Tim Axelrod, Jeremy Mould,  and Brian Schmidt (Research School of Astronomy
and Astrophysics, The Australian National University) report the following
optical photometry of GRB990510 using
the Mount Stromlo 50inch + Macho Camera (measured with respect to the USNO
star at RA = 13:38:00.82, DEC=-80:29:11.7  for which we have assumed
R = 17.2, cf. Galama et al GCN 313). The following observations are Macho R
(effective lambda = 700nm), but transform almost identically to R_c.

      R mag     err   May (UT)   Telescope    

      18.24     0.02   10.514  MSO 50inch
      18.31     0.02   10.522  MSO 50inch
      18.30     0.02   10.529  MSO 50inch
      19.23     0.07   10.775  MSO 50inch
      19.31     0.07   10.783  MSO 50inch    
      19.25     0.04   10.791  MSO 50inch    


The absolute uncertainty in the calibration is not included. The decay
is consistent with a power law, with temporal decay index -0.88 +- 0.03.

Simultaneous observations in Macho-B (effective lambda = 510nm)
show a powerlaw decay of index -0.94 +- 0.04.

This message is citeable.


[GCN OP NOTE:  This circular was received at 20:26 11 May 99 UT,
but was delayed in distribution due to not having a prior vetting account.]
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