[vsnet-grb-info 4182] Retractions of previous Swift-BAT triggers

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5987
SUBJECT: Retractions of previous Swift-BAT triggers
DATE:    07/01/03 18:53:10 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. Barthelmy (GSFC) on behalf of the Swift-BAT Team

This corrects the classification of 27 Swift-BAT triggers since the beginning
of the mission.  In a few cases over the two year period, we did not issue
retraction announcements when there should have been one (in either Notice or
Circular form), for various reasons (e.g. we got busy with the next trigger,
we did not believe it was a non-GRB until just recently, or we just plain
forgot).

In some cases the classification issued in the real-time notice was wrong. 
For example, some notices said a trigger was cause by a GRB when in fact it
was a known source in a variable state, but the source was not in the catalog
used for the real-time notices.  In other cases the real-time classification
was indecisive (i.e. it contained words like "possible").  We apologize for
any inconvenience that the original incorrect classifications may have caused. 

In a few cases we thought we did not need to retract the trigger because we
thought nobody outside the Swift team was notified, when in fact partial
sets of Notices went out to the community.  A hole in the GCN Notice filtering
code was allowing the FOM_OBS and SC_SLEW Notices to be distributed to the
world.  That filtering code correctly blocked the bogus BAT_POS and
BAT_LIGHTCURVE Notices, but allowed the other two through.

The table below contains the Trigger Number, the Trigger Date and Time,
and a Comment about what we are currently classifying the trigger.

TRIGNUM  DATE      TIME        DESCRIPTION

106416   05 Feb 19 14:14:47    FSW bug, old ACS, Vela X-1 misidentified
114292   05 Apr 10 08:38:17    FSW bug, old ACS, Crab mididentified
114959   05 Apr 19 05:47:21    Noise fluctuation
117883   05 May 07 00:21:28    FSW bug, old ACS, known source misidentified
118087   05 May 07 13:33:52    Chance noise coinc with SAX0835.9+5118
123171   05 May 20 11:15:04    Noise fluctuation
131113   05 May 31 23:31:57    S/C drifting in Sun_Reference Safe_Hold mode
131156   05 Jun 01 04:24:45    S/C drifting in Sun_Reference Safe_Hold mode
131160   05 Jun 01 05:17:27    S/C drifting in Sun_Reference Safe_Hold mode
131177   05 Jun 01 10:07:47    S/C drifting in Sun_Reference Safe_Hold mode
131185   05 Jun 01 12:34:21    S/C drifting in Sun_Reference Safe_Hold mode
131213   05 Jun 01 14:55:47    S/C drifting in Sun_Reference Safe_Hold mode
131266   05 Jun 01 22:13:56    S/C drifting in Sun_Reference Safe_Hold mode
131395   05 Jun 02 10:41:45    S/C drifting in Sun_Reference Safe_Hold mode
142851   05 Jun 26 03:30:20    Chance noise coinc with SAX2224.9+5421
146134   05 Jul 15 23:56:08    FSW Bug, bad RA,Dec long Image-trigger
146547   05 Jul 18 13:20:32    FSW Bug, bad RA,Dec long Image-trigger
147704   05 Jul 25 15:57:52    FSW Bug, bad RA,Dec long Image-trigger
147857   05 Jul 26 19:33:36    Chance noise coinc with 4U 1746-370
148146   05 Jul 30 04:14:48    FSW bug, bad RA,Dec values in the notice
148715   05 Aug 02 23:56:16    Bad ACS, roll-only maneuver, Cyg X-1
152762   05 Aug 30 17:13;12    Noise in the Image-domain
158262   05 Oct 04 11;16:48    Chance noise coinc with EXO 0748-676 (or Possibly real EXO detection)
163240   05 Nov 09 21:33:36    Chance noise coinc with IGR00234+6141
178754   06 Jan 24 17:17:35    Chance noise coinc with sw333.4+17.4 (Probably)
179477   06 Jan 29 17:18:39    Chance noise coinc with IGR14175-4641
203045   06 Mar 28 13:50:14    Chance noise coinc with 1E1743.1-2843