TABLE OF CONTENTS:
The GCN system has been modified to incorporate the distribution of GRB locations detected by the COMPTEL instrument on the CGRO spacecraft.
About 5 times a year, there is a GRB in the FOV of COMPTEL that is bright enough for COMPTEL to produce a location.
Like all the other sources of GRB locations within the GCN system, users can elect to receive (or not) this COMPTEL source as well.
The GCN/COMPTEL Notices are archived within the GCN website in the Table of COMPTEL GRBs.
The sequence of activities that produces these GCN/COMPTEL Notices is:
a) If BATSE detects a GRB and it is determined to be in the COMPTEL FOV,
then GCN captures and ftp's the COMPTEL telemetry data to UNH (5 min).
b) A UNH daemon monitors for the incoming telemetry file, processes it, and
creates an Initial location (3-4 min).
c) If the COMPTEL detection significance is > 4.0 sigma,
The Initial location is e-mailed back to GCN, where it is imported, parsed, and
distributed to those sites requesting this notice type (<1 min).
Else, a "could_not_localize" notice is issued.
d) A more systematic grid-search is done on the data and an Update location is issued (8 min).
e) On rare occasions, a piece of the automatic processing does not work as planned,
and then the duty-scientist intervenes to get an improved location.
When this happens, i) additional Updates may be issued; or ii) the Initial location
may be delayed (longest delay to date is 45 minutes).
Baring a processing problem, the total time delay is ~7-8 minutes for the Initial Notice.
and ~15-16 minutes for the Updated Notice.
There are two Notice sub-types for the COMPTEL program. The two sub-types are (1) COMPTEL detected a GRB and the coordinates are listed or (2) COMPTEL did not detect the GRB. Samples of the E-mail, Pager and Short-form Pager distribution methods of the two GCN/COMPTEL Notice sub-types are attached below. The format is very similar to that used for the other sources of GRB locations within the GCN system. Many of the fields are the same except the intensity is now in units of number_of_events, and there is also a detection_significance field.
The Internet socket formats are similarly modified from the others in the GCN system and are described in detail in the socket definition document. Both sub-types are type=30.
Unlike the four sub-types for the BATSE Notices (Original, Final, MAXBC, and LOCBURST), there is no individual filtering for the two COMPTEL sub-types. If a site elects to receive COMPTEL Notices, it will receive both sub-types (the POSITION Notice and the No_detection Notice).
Sites can elect to receive COMPTEL notices. This filtering of the COMPTEL source of notices is controlled by a flag bit in the "sites.cfg" file. There are also dis/enable flag bits for each COMPTEL Notice sub-type. Sites can elect to receive the POSITION notices, but not the No_detection Notice if they so choose. This may be useful to some sites that do not want to receive the approximate 70 No_detection notices per year, but do want to receive the about 5 detection notices per year.
The uncertainty in the location will depend on the source intensity, the spectrum (number of high-energy gamma photons), and its relative position in the COMPTEL FOV. The average 1-sigma statistical accuracy is 1.13deg. Systematic uncertainties are about 30arcmin. The error boxes tend to become elongated (generally in azimuth) as the burst position falls further from the zenith.
Sites should properly recognize Alanna Connors, R. Marc Kippen, and the duty scientist at the time of the burst (either one of the above; or C. Alex Young, S. Kappadath, or J. Ryan) for COMPTEL-RBR; and Scott D. Barthelmy and Paul Butterworth (GSFC for GCN) in any publications discussing follow-up observations using these GCN/COMPTEL locations.
For further information on this, please contact
Alanna Connors (for COMPTEL issues),
Scott Barthelmy (for GCN issues),
or see the
COMPTEL
and
these GCN web pages.
Examples of the two sub-types of the e-mail formats are shown below.
There is an Initial and an Update for the "saw" sub-type, and an Initial
for the "no_saw" sub-type.
The "/////" divider bars are NOT part of the messages.
For those sites/people that use daemons and/or incoming e-mail filters,
the "Subject" lines for the two notices are fixed, and the strings are:
1) GCN/COMPTEL_POSITION
2) GCN/COMPTEL_POSITION
//////////////////////////////////////////////////////////////////////////////
TITLE: GCN/COMPTEL BURST POSITION NOTICE
NOTICE_DATE: Sun 05 Oct 97 19:28:53 UT
NOTICE_TYPE: COMPTEL Initial
TRIGGER_NUM: 6440
GRB_DATE: 10667 TJD; 219 DOY; 97/08/07
GRB_TIME: 66309.08 SOD {18:25:09.08} UT
GRB_COMPTEL_RA: 284.69d {+18h 58m 46s} (J2000),
284.65d {+18h 58m 36s} (current),
283.83d {+18h 55m 19s} (1950)
GRB_COMPTEL_DEC: -39.29d {-39d 17' 23"} (J2000),
-39.29d {-39d 17' 35"} (current),
-39.36d {-39d 21' 30"} (1950)
GRB_ERROR_RA1: 288.31d {+19h 13m 14s} (J2000)
GRB_ERROR_DEC1: -38.01d {-38d 00' 35"} (J2000)
GRB_ERROR_RA2: 284.33d {+18h 57m 19s} (J2000)
GRB_ERROR_DEC2: -36.51d {-36d 30' 35"} (J2000)
GRB_ERROR_RA3: 281.33d {+18h 45m 19s} (J2000)
GRB_ERROR_DEC3: -41.00d {-41d 00' 00"} (J2000)
GRB_ERROR_RA4: 285.49d {+19h 01m 58s} (J2000)
GRB_ERROR_DEC4: -42.59d {-42d 35' 23"} (J2000)
GRB_COMPTEL_INTEN: 31 [events]
GRB_COMPTEL_SIGNIF: 4.0 [sigma]
SUN_POSTN: 137.74d {+09h 10m 57s} +16.26d {+16d 15' 20"}
SUN_DIST: 143.11 [deg]
MOON_POSTN: 183.76d {+12h 15m 03s} -0.23d {-00d 13' 56"}
MOON_DIST: 98.26 [deg]
PROG_VERSION: 12.00
COMMENTS: COMPTEL GRB location.
COMMENTS: Error box indicates 2-sigma statistical
COMMENTS: confidence limits only.
COMMENTS: -----
COMMENTS: Please DO NOT reply to this message!
COMMENTS: Address questions to either:
COMMENTS: Alanna Connors(aconnors@comptel.unh.edu)
COMMENTS: Bernie McNamara(bmcnamar@nmsu.edu)
//////////////////////////////////////////////////////////////////////////////
TITLE: GCN/GRO_COMPTEL BURST POSITION NOTICE
NOTICE_DATE: Fri 31 Oct 97 15:22:55 UT
NOTICE_TYPE: GRO-COMPTEL Update
TRIGGER_NUM: 6440
GRB_DATE: 10667 TJD; 219 DOY; 97/08/07
GRB_TIME: 66309.08 SOD {18:25:09.08} UT
GRB_COMPTEL_RA: 284.73d {+18h 58m 55s} (J2000),
284.69d {+18h 58m 45s} (current),
283.87d {+18h 55m 29s} (1950)
GRB_COMPTEL_DEC: -39.25d {-39d 15' 00"} (J2000),
-39.25d {-39d 15' 11"} (current),
-39.32d {-39d 19' 07"} (1950)
GRB_ERROR_RA1: 288.66d {+19h 14m 38s} (J2000)
GRB_ERROR_DEC1: -38.13d {-38d 07' 47"} (J2000)
GRB_ERROR_RA2: 284.89d {+18h 59m 34s} (J2000)
GRB_ERROR_DEC2: -36.27d {-36d 16' 11"} (J2000)
GRB_ERROR_RA3: 280.60d {+18h 42m 24s} (J2000)
GRB_ERROR_DEC3: -41.16d {-41d 09' 35"} (J2000)
GRB_ERROR_RA4: 284.52d {+18h 58m 05s} (J2000)
GRB_ERROR_DEC4: -43.16d {-43d 09' 35"} (J2000)
GRB_COMPTEL_INTEN: 31 [events]
GRB_COMPTEL_SIGNIF: 4.0 [sigma]
SUN_POSTN: 137.74d {+09h 10m 57s} +16.26d {+16d 15' 20"}
SUN_DIST: 143.15 [deg]
MOON_POSTN: 183.76d {+12h 15m 03s} -0.23d {-00d 13' 56"}
MOON_DIST: 98.29 [deg]
PROG_VERSION: 12.00
COMMENTS: GRO-COMPTEL GRB location.
COMMENTS: Error box indicates 2-sigma statistical
COMMENTS: confidence limits only.
COMMENTS: -----
COMMENTS: Please DO NOT reply to this message!
COMMENTS: Address questions to either:
COMMENTS: Alanna Connors(aconnors@comptel.unh.edu)
COMMENTS: Bernie McNamara(bmcnamar@nmsu.edu)
COMMENTS: *****************************************************
COMMENTS: Burst location uncertainty contour (2-sigma) follows.
COMMENTS: 50 contour points, J2000 coordinates in deg
COMMENTS: IP RAsc Decl IP RAsc Decl
COMMENTS: -----------------------------------------------------
COMMENTS: 01 287.30 -39.89 26 282.42 -39.19
COMMENTS: 02 287.50 -39.59 27 282.20 -39.43
COMMENTS: 03 287.68 -39.27 28 282.00 -39.67
COMMENTS: 04 287.82 -38.95 29 281.80 -39.91
COMMENTS: 05 287.89 -38.61 30 281.60 -40.15
COMMENTS: 06 287.86 -38.25 31 281.43 -40.40
COMMENTS: 07 287.70 -37.92 32 281.29 -40.67
COMMENTS: 08 287.61 -37.76 33 281.17 -40.94
COMMENTS: 09 287.46 -37.62 34 281.10 -41.25
COMMENTS: 10 287.30 -37.50 35 281.27 -41.52
COMMENTS: 11 287.12 -37.39 36 281.69 -41.61
COMMENTS: 12 286.76 -37.26 37 282.11 -41.64
COMMENTS: 13 286.37 -37.18 38 282.53 -41.70
COMMENTS: 14 285.98 -37.11 39 282.97 -41.71
COMMENTS: 15 285.59 -37.09 40 283.39 -41.66
COMMENTS: 16 285.20 -37.17 41 283.81 -41.58
COMMENTS: 17 284.82 -37.27 42 284.21 -41.46
COMMENTS: 18 284.46 -37.41 43 284.59 -41.32
COMMENTS: 19 284.14 -37.61 44 284.96 -41.16
COMMENTS: 20 283.85 -37.80 45 285.33 -41.02
COMMENTS: 21 283.59 -38.01 46 285.70 -40.88
COMMENTS: 22 283.34 -38.24 47 286.07 -40.73
COMMENTS: 23 283.12 -38.48 48 286.43 -40.57
COMMENTS: 24 282.88 -38.71 49 286.75 -40.36
COMMENTS: 25 282.65 -38.95 50 287.04 -40.14
COMMENTS: -----------------------------------------------------
COMMENTS:
COMMENTS:
//////////////////////////////////////////////////////////////////////////////
TITLE: GCN/GRO_COMPTEL BURST POSITION NOTICE
NOTICE_DATE: Sun 05 Oct 97 19:32:52 UT
NOTICE_TYPE: COMPTEL Initial
TRIGGER_NUM: 6440
GRB_DATE: 10585 TJD; 137 DOY; 97/05/17
GRB_TIME: 1139.40 SOD {00:18:59.40} UT
COMMENTS: COMPTEL was not able to localize this GRB.
COMMENTS: Rapid COMPTEL localization of this burst
COMMENTS: is not possible.
COMMENTS: -----
COMMENTS: Please DO NOT reply to this message!
COMMENTS: Address questions to either:
COMMENTS: Alanna Connors(aconnors@comptel.unh.edu)
COMMENTS: Bernie McNamara(bmcnamar@nmsu.edu)
Examples of the two sub-types of the (regular) pager formats are shown below. There are no "Subject" lines for the e-mails sent to the pager companies because the Subject line would use up valuable character counts from the maximum displayable for the body of the message. The RA,Dec are Current Epoch.
////////////////////////////////////////////////////////////////////////////// GCN/GRO_COMPTEL GRB Initial RA=284.69d DEC=-39.29d TIME: 18:25:09.08 UT I=31 GRO-COMPTEL GRB Coordinates.
////////////////////////////////////////////////////////////////////////////// GCN/GRO_COMPTEL GRB Update RA=284.73d DEC=-39.25d TIME: 18:25:09.08 UT I=31 GRO-COMPTEL GRB Coordinates.
////////////////////////////////////////////////////////////////////////////// GCN/GRO_COMPTEL GRB Initial TIME: 00:18:59.40 UT GRO-COMPTEL was not able to localize this GRB.
Examples of the two sub-types of the short-form pager format are shown below. There are no "Subject" lines for the e-mails sent to the pager companies because the Subject line would use up valuable character counts from the maximum displayable for the body of the message. And it was the very limited display character count of some companies that motivated the short-form pager method in the first place. The RA,Dec are 1950 Epoch.
////////////////////////////////////////////////////////////////////////////// GRO-COMPTEL RA=283.87 DEC=-39.36d
////////////////////////////////////////////////////////////////////////////// GRO-COMPTEL was not able to localize this GRB.
An example of the Subject-only pager/cell_phone format is shown below. Only the "Subject" line for these e-mails sent to the pager companies because that's the only part of the e-mail they display on the pager/cellphone. The RA,Dec are Current Epoch.
////////////////////////////////////////////////////////////////////////////// GRO-COMPTEL RA=283.87 DEC=-39.36d
////////////////////////////////////////////////////////////////////////////// GRO-COMPTEL was not able to localize this GRB (Trig=6439).