GRB 000408

A. Henden (USRA/USNO), C. Luginbuhl (USNO),
B. Canzian (USNO) on behalf of the USNO GRB Team,
Vijay Mohan, S. B. Pandey and Ram Sagar, UPSO (Nainital),
David Alcalde and David Martinez-Delgado, IAC (Tenerife),
Jose Maria Castro Ceron, ROA (San Fernando),
Alberto Castro-Tirado,
     LAEFF-INTA (Madrid) and IAA-CSIC (Granada),
and Javier Gorosabel Urkia, DSRI report:

We have observed the entire preliminary IPN
error box for GRB 000408 (GCN#626
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 ) as well
as the refined error box (GCN#632
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 )
from several sites and on both available nights.
Because of the shape of the error box, mosaics were
used at each site, limiting the depth of exposure
for any particular field.  Only R-band observations
were made.  A log of the observations is given below.

TEL.       MARCH (UT)      TEXP   RA      DEC    
--------------------------------------------------
IAC80   8.9352 --  9.0103  3800 9:10:41 +66:34:15
IAC80   9.0094 --  9.0140   200 9:09:39 +66:34:15
IAC80   9.0141 --  9.0187   200 9:08:39 +66:34:47
IAC80   9.0176 --  9.0223   200 9:07:42 +66:35:15
IAC80   9.0210 --  9.0257   200 9:06:41 +66:35:47
IAC80   9.0248 --  9.0294   200 9:11:41 +66:34:50
IAC80   9.0292 --  9.0338   200 9:12:40 +66:34:21
IAC80   9.0327 --  9.0373   200 9:13:42 +66:33:52
IAC80   9.0360 --  9.0407   200 9:14:41 +66:33:20
IAC80   9.0360 --  9.0407   200 9:14:41 +66:33:20
IAC80   9.9319 --  9.9741  3600 9:08:26 +66:33:28
UPSO    9.7667 --  9.7724   500 9:48:41 +66:35:15
UPSO    9.7764 --  9.7821   500 9:10:27 +66:35:08
USNO    9.136  --  9.225   1800 9:13:41 +66:33:51
USNO    9.128  --  9.216   1800 9:12:02 +66:33:51
USNO    9.121  --  9.209   1800 9:10:20 +66:33:51
USNO    9.145  --  9.233   1800 9:08:41 +66:33:51
USNO    9.153  --  9.241   1800 9:07:01 +66:33:51
USNO   10.154  -- 10.176   1800 9:13:41 +66:33:51
USNO   10.176  -- 10.198   1800 9:12:02 +66:33:51
USNO   10.130  -- 10.152   1800 9:10:20 +66:33:51
USNO   10.199  -- 10.229   1800 9:08:41 +66:33:51
USNO   10.229  -- 10.251   1800 9:07:01 +66:33:51

POSS-II/F for this field is not available through
DSS.  However, it is available through the USNO
PMM pixel database.  We have placed three files
on the anon ftp server that cover the error box:
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb000408-1.jpg
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb000408-2.jpg
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb000408-3.jpg
in order of increasing RA.  A finder chart from POSS-I
with the refined error box marked on it is at:
http://www.dsri.dk/~jgu/grb000408/grb000408.dss.gif

No candidate was found above the POSS-II plate limit.
The two deep exposure sets from USNO were blinked
to look for transients below the POSS-II plate
limit.  While several candidates are present,
none is entirely convincing at a limiting
magnitude of approximately R=21.5.  However, for
completeness, here are the two best candidates
inside the error box, both R=20.5 or fainter:
A  09:11:04.82  +66:33:31.3  J2000
B  09:08:51.36  +66:33:36.5  J2000 

Preliminary BVRI all-sky calibration of the central
part of the error box can be found at
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb000408.dat
The external zero-point errors for this file are estimated
to be +/- 0.05mag.  Refinement of this photometry
will be performed in late April if an OT is discovered.

Further data analysis is in progress.

[GCN OPS NOTE (11 Apr 00):  The co-authors S.B.Pandey & David Martinez-Delgado
were added to the list.]

K. Hurley, R. M. Kippen, and T. Cline, on behalf of the Ulysses,
BATSE, and NEAR GRB teams, report:

We have derived a refined error box for GRB000408 (=BATSE
8069, GCN 626
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 ), whose area is ~60 sq. arcmin.  Its coordinates
are:

  RA(2000)                 DEC(2000)            
9 h  9 m 17.91 s     +66 o 34 '  49.78 "  (CENTER)
9 h 11 m 30.33 s     +66 o 32 '  31.07 "  (CORNER)
9 h  8 m 10.97 s     +66 o 33 '  43.86 "  (CORNER)
9 h 10 m 24.59 s     +66 o 35 '  54.27 "  (CORNER)
9 h  7 m  3.18 s     +66 o 37 '   2.96 "  (CORNER)


Further refinements are still possible.

K.S. Baliyan, U.C. Joshi, S. Mondal, S. Chandrasekhar, J.K. Jain
   and B.G. Anandrao (MIRO-PRL, Ahmedabad, India) report:
   
   Optical afterglow follow up observations of the grb000408 were
   made covering IPN error box (GCN 626
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 ) on April 9, 2000, beginning
   16:15 UT. The 1024*1024 CCD (FOV 6'*6') mounted on 1.2 M IR
   telescope at Mt Abu IR Observatory, operated by Physical Research 
   Laboratory, Ahmedabad- India, was used to get 600 seconds
   exposures each in V and I filters at each location covering the 
   error box. 
   The data analysis is in progress and an image will be put on the
   laboratory web page when available. We also intend to continue
   observations of the optical counterpart tonight as well.
 
   This message may be cited.

H. S. Park, R. Porrata (LLNL), G. G. Williams, D. Hartmann (Clemson),
K. Hurley (UCB), S. Barthelmy (GSFC)
report on behalf of the LOTIS collaboration:

The realtime BATSE trigger came at 7:37 pm local time when the sky
was too bright for observation. However, Lotis' wide-field-of-view
sky patrol data covered the grb000408 IPN error box (GCN 626
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 ) 
1.64 hours after the burst (15241s UTC). Comparison of the 
images with the previous sky patrol images, the Digital Sky Survey, 
and the Guide Star Catalog reveal no OT within the IPN error box 
brighter than m = 15.0 (5-sigma). No astronomical filter was used 
during these observations. Further analysis is in progress.

This message may be cited.

K. Hurley, S. Barthelmy, R. M. Kippen, and T. Cline, on behalf
of the Ulysses, BATSE, and NEAR GRB teams, report:

Ulysses, BATSE, and NEAR observed GRB000408 (=BATSE 8069)
at 9348 s UT.  As observed by Ulysses, this burst had a
T90 duration of 2.5 s, a 25-100 keV fluence of 7.4x10^-6 erg/cm^2,
and a peak flux over 0.5 s of 3.7x10^-6 erg/cm^2 s.  Preliminary
triangulation gives a ~200 sq. arcmin. error box with the
following coordinates:

     RA(2000)           DEC(2000)
9 h 10 m 31.86 s    66 o 34 '  35.72 "  (CENTER)
9 h 14 m 57.83 s    66 o 30 '  25.93 "  (CORNER)
9 h  7 m 41.72 s    66 o 33 '  18.90 "  (CORNER)
9 h 13 m 19.82 s    66 o 35 '  43.51 "  (CORNER)
9 h  5 m 56.89 s    66 o 38 '  22.95 "  (CORNER)

It should be possible to refine this error box considerably
within 24 h, when the high time resolution data become
available.