TABLE OF CONTENTS:
1. Introduction and Background:
The GCN system distributes location information derived from the
Interplanetary Network (IPN) @ UC Berkeley and
the IPN @ GSFC.
There are 3 variations of this IPN-based set of Notices.
These IPN Notices are different than the regular GCN Notice
(which contain burst information from a single instrument detection)
in that these IPN Notices combine burst information from 1, 2, 3 or more spacecraft.
The IPN is a system of spacecraft that use gamma-ray arrival time information
at multiple spacecraft to triangulate the direction of a GRB.
The mission-instruments that currently (as of Aug 2008) constribute to the IPN are:
Mars_Odyssey-HEND, Mars_Odyssey-GRS, RHESSI, KONUS-Wind, Swift-BAT, MESSENGER-GRNS,
Suzaku-WAM, INTEGRAL-SPIACS, SuperAGILE, AGILE-GRID, AGILE-MCAL, Fermi-GBM, and Fermi-LAT.
Kevin Hurley (UCB),
khurley@sunspot.ssl.berkeley.edu is the PI for the IPN.
2. The IPN Notice Types:
There are three variations of GCN/IPN information:
(1) IPN_RAW,
(2) IPN_POS, and
(3) IPN_SEGMENT.
These types along with their inputs and outputs are summarized in Table 1.
2.1) The IPN_RAW type comes in two sub-types:
(a) a timestamp-only from a countrate increase detection by a single spacecraft, and
(b) an IPN annulus (discontinued) derived when two spacecraft detect the same burst.
The annuli are narrow (2-30 arcmin) and have a radius of 0-90 deg on the sky.
Here is the announcement for this new Notice type (the 2008 implementation).
See the list of archived Raw Notices.
2.2) The IPN_POS type is the result of a 3 (or more) spacecraft IPN timing triangulation solution.
These are burst positions with small error boxes (as opposed to the annuli, segments, or timestamps described below).
(On rare occaisions there will be two error boxes in the IPN_Position Notice
instead of the usual single error box.)
Here is the announcement for this new Notice type (Sep 2000).
See the list of archived Position Notices.
2.3) The IPN_SEGMENT type combines the intersection of a 2-spacecraft-IPN annulus and an error circle
from spacecraft-instrument that produces a large error circle. Combining the annulus plus an error circle
yields a segment section along the annulus.
In the past (1995-2001), this large error circle instrument was BATSE.
This IPN_SEGMENT type might resume by using Fermi-GBM as the large error-circle instrument.
The annuli segments are long (2-10 deg) and narrow (2-30 arcmin).
See the list of archived annulus Segment Notices.
| TYPE | NUM S/C | CONTRIBUTION CONTENT | OUTPUT CONTENT |
|---|---|---|---|
| IPN_RAW(1) | 1 | A single Rate Increase Timestamp | A single Timestamp |
| IPN_RAW(2) | 2,3,.. | 2 (or more) instruments with Rate Increase Timestamps | A combined Timestamp with multi-missiong flag bits |
| IPN_RAW(3) | 2 | A Rate Increase Timestamp from each s/c | Full annulus |
| IPN_POS | 3,4,5... | A Rate Increase Timestamp from each s/c | Error box |
| IPN_SEGMENT | 2 | A Full Annulus and a BATSE Error Circle | Annulus segment DISCONTINUED |
3. The "IPN" Notice Sequence of Activities:
The following 3 sections describe the sequence of activities, data contributors,
and the processing involved to produce the respective Notice types.
3.1) For IPN_RAW:
a) Any of the ~8 mission-instruments that contribute to the IPN systen (as of Aug 08)
search their respective data sets looking for countrate increases.
Some missions use human-search techniques and others use automated searches.
b) If the increase is determined to be due to a burst (as determined by humans in the loop
using the lightcurve shape and spectral information), then a message is sent to GCN
giving the date and time of the burst. The automated searches send to GCN.
c) A daemon on the GCN imports this message, converts it to the standard GCN format,
and distributes it to those sites that have this IPN_RAW type enabled.
d) GCN compares the newest IPN Timestamp message to the previous messages
and if a temporal match is found, then a 2nd IPN_RAW notice is distributed with the appropriate flagbits
indicating which mission-instruments contributed and combined timestamp. (This temporal match
makes the GRB-ness very high compared to a single-mission timestamp which is commonly noise.)
3.2) For IPN_POS:
a) The GCN system also runs "auto_near" (now defuuct) and "auto_konus" programs.
These two programs automatically receive daily transfers of data from the two spacecraft,
process them looking for GRBs, and when GRBs are found,
the extracted lightcurves (with timing information) are sent to K.Hurley's daemon at UCB.
b) A daemon on the UCB machine monitors for incoming NEAR and KONUS light curves,
and when it detects one it looks to see if the appropriate section
of the Ulysses data has been received from JPL/DSN.
If that portion of the data has not arrived,
it continues to periodically check until it does arrive.
c) Depending on the relative timing of the GRB and the data dumps through the DSN,
the wait can be 1-25 hours (more on the weekends).
d) When the Ulysses data has been transferred from JPL,
it is searched for a matching GRB and when a significant enough match is found,
IPN annuli are calculated and the resulting position(s) is sent back to GCN for distribution.
3.3) For IPN_SEGMENT: (DISCONTINUED)
The IPN_SEG Notices use the data from two different spacecraft.
The exact sequence of steps is:
In the CGRO-BATSE era:
a) When the GCN program detects a burst in the BATSE telemetry stream,
it produces a BATSE light curve in the 20-100 keV energy band
using the 1-sec sampled DISCLA data,
and sends that light curve to a machine at UCB. (T+5 min)
b) A daemon on the UCB machine monitors for incoming BATSE light curves,
and when it detects one it looks to see if the appropriate section
of the Ulysses data has been received from JPL/DSN.
If that portion of the data has not arrived,
it continues to periodically check until it does arrive.
c) Depending on the relative timing of the GRB and the data dumps through the DSN,
the wait can be 1-25 hours (more on the weekends).
d) When the Ulysses data has been transferred from JPL,
it is searched for a matching GRB and when a significant enough match is found,
an IPN annulus is calculated and sent back to GSFC.
e) This annulus is combined with the latest/best
BATSE-Original/-Final/-MAXBC/-LOCBURST/-AD error circle that is available
and a notice is composed and sent
to all GCN sites (this is the human-in-the-loop part).
The GCN system captures and automatically transfers to Kevin Hurley (UC Berkeley)
the BATSE light curve for a GRB. This gets the appropriate data to UCB a couple days
before the Huntsville BATSE team could do so, thus eliminating a couple days
from the total time delay. The range of time delays (T_burst to Notice_time)
is on average 24 to 48 hours (with the shortest being 11 hours to date).
The GCN system also processes the telemetry downloads from the Wind-KONUS and NEAR-XGRS instruments,
finds & extracts the GRBs in those data, and sends the lightcurves to the IPN daemon at UCB.
And from then on the sequence of processing events is the same, and the distribution
of the various IPN Notices types is the same. The time delays for these Notices
are comparable to the BATSE-Ulysses-based Notices, because the TM download latencies
of Wind and NEAR are comparable to Ulysses (CGRO-BATSE is the only real-time system, currently).
In the Fermi-GBM era:
It is the same as above except that the BATSE lightcurve is replaced with the GBM lightcurve, and
the BATSE error circle is replaced with the GBM error circle, and
Ulysses is replaced by a combination of non-earth-orbit spacecraft.
This GBM-form of the IPN_SEG notice has not yet been implemented.
IPN_RAW:
SubType 1) Since this type contains only the timestamp of a GRB/Transient/noise
(and sometimes an annulus on the sky), it is envisioned that this Notice type
is suitable for those sites that want to time-correlate any detections in their instruments
with those mission-instruments in the IPN network. (This might include not only
wide-angle optical cameras, but also neutrino, gravitational radiation,
and TeV detectors; although, of course, anybody is free to receive this Notice type.)
Not all timestamp notices will be followed up with localization information;
please contact Kevin Hurley and/or Valentin Pal'shin (khurley AT ssl.berkeley.edu,
val AT mail.ioffe.ru) if you need further information on an event.
SubType 2) Since this means 2 (or more) mission-instruments detected rate incrases
at the same time (within the light-travel time window wrt thir locations inthe solar system,
the confidence level that the even is astrophysical (ie not noise) is greatly increased.
It can bus used by follow-up team to determine if a given event is real or not.
SubType 3) This subtype contains an annulus, and as such, is only useful to the IPN Teams
as part of further/on-going analysis to refine the location of the event to a box.
IPN_POS:
These can be used like any of the other error box/circle position notices
by follow-up instruments with small (10-20 arcmin) FOV.
IPN_SEG: (DISCONTINUED)
These can be use by either (a) instruments with large FOVs (1-10 deg), or
(b) by small FOV instruments that are willing to tile the annulus segment.
For IPN_RAW Notice type, the annuli are narrow (2-30 arcmin) and have a radiius of 0-90 degrees.
The timestamp-only subtypes do not have any positional information.
For IPN_POS Notices,
the error boxes will be in the several arcmin and above range.
For about 55% of the Notices there will be only a single error box,
but because 3 spacecraft yield only 2 unique annuli and these 2 annuli cross in 2 locations,
there can be 2 error boxes reports (~25% of the cases).
A 4th spacecraft or other directional information from some spacecraft
(e.g. imaging from SAX-WFC or north/south ecliptic hemispheres from Wind-KONUS, etc).
For IPN_SEG Notice type, the annuli segments are long (2-10 deg) and narrow (2-30 arcmin)
yielding an error box area of 4 sq.arcmin to 5 sq.deg.
| TYPE | SHAPE | SIZE |
|---|---|---|
| IPN_RAW(1) | - | - |
| IPN_RAW(2) | - | - |
| IPN_RAW(3) | Full annulus | 2-30 arcmin wide, 0-90 deg radius |
| IPN_SEGMENT | Annulus segment | 2-30 arcmin wide by 2-10 deg long DISCONTINUED |
| IPN_POS | Box | (10-20) by (60-180) arcmin |
For IPN_RAW Notice type, the delay between the trigger time and the notice
will be a function of the downlink times of the various missions,
but most delays will not exceed one day, and should be considerably shorter in most cases.
For IPN_POS Notices, there will be an additional delay of 4-24 hours
while the humans-in-the-loop calculate the various annuli to produce an error box.
6. Distribution Methods & Filter Functions:
Unlike all the other GCN notice types, the IPN_SEG Notices are currently only available
via the full-format e-mail distribution method. The data set is not compatible
with the Pager (long and short forms), or the Internet socket methods.
See Table 3 for a breakdown of what Notice IPN Types are available via which distribution methods.
| METHOD | RAW | SEG | POS |
|---|---|---|---|
| Socket | YES | NO | YES |
| XML_Socket | YES | NO | YES |
| YES | YES | YES | |
| Pager | YES | NO | YES |
| SPager | YES | NO | YES |
| Subject | YES | NO | YES |
| Subject hh:mm | YES | NO | YES |
| VOEevet_email | YES | NO | YES |
| VOEevet_Socket | YES | NO | YES |
Sites can elect to receive each of the 3 IPN Notice types on a Type-by-Type basis.
There is a separate dis/enable bit for each type. There is no SubType filtering
(ie Timestamp-only vs Annulus) for the IPN_RAW type.
Filtering method "Visible" and "Night" do not apply the IPN_RAW and IPN_SEGMENT types.
However, Timedelay and ErrorBox_size filters do apply to all 3 types, as do many of the other ~13 filtering functions.
For all 3 types, the format of the full-format e-mail form (appended below)
is very similar to the other sources in the GCN.
It is based on a "TOKEN: value" scheme to allow for both
the easy reading by humans and the easy parsing by computer daemons.
The packing format and content of the socket packet method is also very similar
to that used in the other socket packets. Those GCN sites using the Internet socket method
should refer to the socket definition document
to get the details (packet types 31, 32, and 39).
8.1) IPN_RAW
Both variations of the Notice type are shown in Section 10.3 (the Timestamp-only and the Annulus).
8.2) IPN_POS
Both variations of this Notice type are shown in Section 10.1
The single-box form is like the other notice type with the exception
that it has the RA,Dec locations for the 4 corners of the box specified.
The two-box form has the center and 4 corners of the second box also given.
8.3) IPN_SEG (DISCONTINUED)
After the twenty or so lines of the "TOKEN: value's", a set of RA,Dec,Distance values
sampled along the center-line of the annulus segment are listed.
These RA,Dec values span the plus/minus 3-sigma confidence limits along the arc
based on the uncertainty (statistical plus systematic)
of the mission-instrument that provided the error circle.
(In the past this was the BATSE-Original/-Final/MAXBC/-LOCBURST/-AD locations;
and now it will be the Fermi-GBM error circles.)
The distance value is the angular distance between the error-circle location
and the sampled position along the arc.
[Note: Earlier forms (pre 12Dec97) of these IPN_SEGMENT Notices did not have
the distance column and only had the "Most Probably" location identified.]
The packing format and content of the socket packet method is also very similar
to that used in the Original packets (type=1). Those GCN sites using the Internet socket method
should refer to the socket definition document
to get the details (this is packet_type=32).
For more information, please contact:
Scott Barthelmy (NASA-GSFC) (301-286-3106)
scott@lheamail.gsfc.nasa.gov
for GCN matters, and
Kevin Hurley (UCB)
khurley@sunspot.ssl.berkeley.edu
or
Valentin Pal'shin (Ioffe Physico-Technical Institute)
val@mail.ioffe.ru
for IPN related issues.
Shown below are two full-format email examples of the two subtypes:
(Note the contents are somewhat constructed to show the variety
of the data product -- do not take these values as real GRBs.)
===================== A Timestamp-only Notice Example =======================
TITLE: GCN/IPN RAW NOTICE
NOTICE_DATE: Mon 30 Jul 12 20:18:31 UT
NOTICE_TYPE: IPN Time_only
TRIGGER_DATE: 16137 TJD; 211 DOY; 12/07/29
TRIGGER_TIME: 39374.23 SOD {10:56:14.23} UT
COMMENTS: IPN_RAW timestamp-only notice.
COMMENTS: The Suzaku-WAM instrument contributed to this notice.
===================== An Annulus Notice Example =============================
TITLE: GCN/IPN RAW NOTICE
NOTICE_DATE: Thu 21 Aug 08 05:03:30 UT
NOTICE_TYPE: IPN Annulus
TRIGGER_NUM: 1234
GRB_DATE: 14699 TJD; 234 DOY; 08/08/21
GRB_TIME: 7226.27 SOD {02:00:26.27} UT
IPN_CENTER_RA: 75.409d {+05h 01m 38s} (J2000)
IPN_CENTER_DEC: +55.199d {+55d 11' 56"} (J2000)
IPN_RADIUS: +54.8501d
IPN_WIDTH: +0.2202d = 13.21 [arcmin] = 792.36 [arcsec]
IPN_WINDOW: n/a [sec]
EVENT_DUR: 22.19 [sec]
SUN_POSTN: 150.67d {+10h 02m 41s} +11.99d {+11d 59' 22"}
SUN_DIST: 148.40 [deg]
MOON_POSTN: 18.71d {+01h 14m 50s} +13.01d {+13d 00' 47"}
MOON_DIST: 22.54 [deg]
COMMENTS: IPN annulus notice.
COMMENTS: This is definitely a GRB.
COMMENTS: The Suzaku-WAM instrument contributed to this notice.
COMMENTS: The Konus-Wind instrument contributed to this notice.
Details of the content of the IPN_RAW E-mail: The "trig_num" is some mission-specific identification number. It is optional; not all missions-instruments have an identification number. The "grb_date" is the Truncated Julian Day of the burst trigger, eg. TJD=13370 is 01 Jan 2005. The "grb_time" is the UT seconds-of-day (SOD) of the burst trigger. The "ipn_center_ra" & "ipn_center_dec" are the RA,Dec coordinates of the center of the IPN annulus (J2000). This field is valid only if the "trigger_id" 2^0 bit is a 0. The "ipn_radius" is the radius to the center of the IPN annulus. This field is valid only if the "trigger_id" 2^0 bit is a 0. The "ipn_width" is the 3-sigma width of the IPN annulus. The units are 0.0001-degrees (ie the fl.pt. error was multiplied by 10000 and then integerized). This field is valid only if the "trigger_id" 2^0 bit is a 0. The "ipn_window" is the amount of time slop that the Timestamp could vary depending on the direction of the burst wavefront (eg for a LEO s/c, this would be +-0.022 sec, and for Mars Observer, it would range from +/-250 sec to +/-1250 sec depending on the relative positions of Mars and Earth). The "event_duration" is the duration of the event in the specified instrument (see Misc flag bits). (Note that the different mission-instruments have different sensitivities and energy windows, so for a given GRB, there will be variations in this value from one instrument to the next.)
Here are two examples of the full e-mail distribution method.
The first is an example of a 1-box Notice. In addition to the usual first few ilnes
which are common to all GCN Notices, ther eis the RA,Dec for the center of the error box,
then the RA,Dec of the 4 corners of the error box,
the radius of the circle which circumscibes the diamond-shapped box,
the area of the box in square arcminutes, the peak flux, fluence, and duration
of the burst (if known; in first example they are not known;
they are in the second example), and
then the usual locations/distances of the Sun amd Moon, plus some comments.
The second example is that of a 2-box Notice. All the fields for the 1-box Notice are present,
plus there is an additional RA,Dec for the center of the second box and the RA,Dec's for its 4 corners.
The time interval for the PEAK_FLUX measurement may or may not be present from Notice to Notice.
===================== A Single Box Notice Example =============================
TITLE: GCN/IPN POSITION NOTICE
NOTICE_DATE: Sun 03 Sep 00 18:59:47 UT
NOTICE_TYPE: IPN Single Box
IPN_NUMBER: 190
GRB_DATE: 11776 TJD; 233 DOY; 00/08/20
GRB_TIME: 31024.00 SOD {08:37:04.00} UT
GRB_IPN_RA: 120.1544d {+08h 00m 37s} (J2000),
120.1616d {+08h 00m 39s} (current),
119.5881d {+07h 58m 21s} (1950)
GRB_IPN_DEC: -17.1604d {-17d 09' 36"} (J2000),
-17.1622d {-17d 09' 43"} (current),
-17.0217d {-17d 01' 17"} (1950)
GRB_ERROR1_RA1: 120.0077d {+08h 00m 02s} (J2000)
GRB_ERROR1_DEC1: -17.2444d {-17d 14' 39"} (J2000)
GRB_ERROR1_RA2: 120.5493d {+08h 02m 12s} (J2000)
GRB_ERROR1_DEC2: -16.7594d {-16d 45' 33"} (J2000)
GRB_ERROR1_RA3: 119.7892d {+07h 59m 09s} (J2000)
GRB_ERROR1_DEC3: -17.5441d {-17d 32' 38"} (J2000)
GRB_ERROR1_RA4: 120.3031d {+08h 01m 13s} (J2000)
GRB_ERROR1_DEC4: -17.0753d {-17d 04' 30"} (J2000)
GRB_ERROR: 21.28 [arcmin radius, 3 sigma]
GRB_BOX_AREA: 196 [sq.arcmin]
GRB_PEAK_FLUX: unknown [erg/cm2/sec]
GRB_FLUENCE: unknown [erg/cm2]
GRB_DURATION: unknown [sec]
SUN_POSTN: 149.82d {+09h 59m 17s} +12.30d {+12d 17' 42"}
SUN_DIST: 41.55 [deg]
MOON_POSTN: 27.27d {+01h 49m 05s} +5.65d {+05d 39' 10"}
MOON_DIST: 94.42 [deg]
COMMENTS: IPN triangulation localization.
COMMENTS: This is a preliminary, 3 sigma error box.
COMMENTS: GCN message is being issued.
===================== A Double Box Notice Example =============================
TITLE: GCN/IPN POSITION NOTICE
NOTICE_DATE: Sun 03 Sep 00 18:59:02 UT
NOTICE_TYPE: IPN Double Box
IPN_NUMBER: 187
GRB_DATE: 11776 TJD; 233 DOY; 00/08/20
GRB_TIME: 31024.00 SOD {08:37:04.00} UT
GRB_IPN_RA: 120.1544d {+08h 00m 37s} (J2000),
120.1616d {+08h 00m 39s} (current),
119.5881d {+07h 58m 21s} (1950)
GRB_IPN_DEC: -17.1604d {-17d 09' 36"} (J2000),
-17.1622d {-17d 09' 43"} (current),
-17.0217d {-17d 01' 17"} (1950)
GRB_ERROR1_RA1: 120.0077d {+08h 00m 02s} (J2000)
GRB_ERROR1_DEC1: -17.2444d {-17d 14' 39"} (J2000)
GRB_ERROR1_RA2: 120.5493d {+08h 02m 12s} (J2000)
GRB_ERROR1_DEC2: -16.7594d {-16d 45' 33"} (J2000)
GRB_ERROR1_RA3: 119.7892d {+07h 59m 09s} (J2000)
GRB_ERROR1_DEC3: -17.5441d {-17d 32' 38"} (J2000)
GRB_ERROR1_RA4: 120.3031d {+08h 01m 13s} (J2000)
GRB_ERROR1_DEC4: -17.0753d {-17d 04' 30"} (J2000)
GRB_IPN2_RA: 134.3352d {+08h 57m 20s} (J2000)
GRB_IPN2_DEC: -8.8200d {-08d 49' 11"} (J2000)
GRB_ERROR2_RA1: 134.4769d {+08h 57m 54s} (J2000)
GRB_ERROR2_DEC1: -8.7360d {-08d 44' 09"} (J2000)
GRB_ERROR2_RA2: 133.7972d {+08h 55m 11s} (J2000)
GRB_ERROR2_DEC2: -8.9647d {-08d 57' 52"} (J2000)
GRB_ERROR2_RA3: 134.8437d {+08h 59m 22s} (J2000)
GRB_ERROR2_DEC3: -8.6931d {-08d 41' 34"} (J2000)
GRB_ERROR2_RA4: 134.1915d {+08h 56m 46s} (J2000)
GRB_ERROR2_DEC4: -8.9054d {-08d 54' 18"} (J2000)
GRB_ERROR: 21.28 [arcmin radius, 3 sigma]
GRB_BOX_AREA: 196 [sq.arcmin]
GRB_PEAK_FLUX: 2.7e-06 [erg/cm2/sec] in a 0.50 sec interval
GRB_FLUENCE: 3.9e-05 [erg/cm2]
GRB_DURATION: 39.0 [sec]
SUN_POSTN: 149.82d {+09h 59m 17s} +12.30d {+12d 17' 42"}
SUN_DIST: 41.55 [deg]
MOON_POSTN: 27.27d {+01h 49m 05s} +5.65d {+05d 39' 10"}
MOON_DIST: 94.42 [deg]
COMMENTS: IPN triangulation localization.
COMMENTS: This is a preliminary, 3 sigma error box.
COMMENTS: GCN message is being issued.
This shows the format of the GCN/IPN_SEG e-mail messages sent to all GCN sites.
The format is of the form "TOKEN: value(s)" on each line.
This format is a reasonable compromise between
human readable and machine readable/parsable formats.
A more detailed explanation of the contents of this notice type is given after this example.
TITLE: GCN/IPN/HUNTSVILLE LOCALIZATION
NOTICE_TYPE: Final (based on the Huntsville AD Report location)
NOTICE_DATE: Tue Feb 10 02:09:09 GMT 1998
TRIGGER_NUM: 6593
GRB_DATE: 98/02/08
GRB_TIME: 12:50:59.93 UT
BACO_RA: 55.38d {+03h 41m 31s} (J2000)
BACO_DEC: -72.28d {-72d 17' 01"}
HUNT_RA: 61.09d {+04h 04m 21s} (J2000)
HUNT_DEC: -75.50d {-75d 29' 45"}
HUNT_ERR: 1.63 [degees radius, statistical only]
B_H_DELTA: 3.57 [deg]
HUNT_SC_AZ: 301.30 [deg]
HUNT_SC_EL: -22.20 [deg] {Zen_angle=112.20}
SUN_POSTN: 321.98d {+21h 27m 54s} -14.95d {-14d 57' 09"} (Current)
SUN_B_DIST: 76.80 [deg]
MOON_POSTN: 106.91d {+07h 07m 38s} +18.25d {+18d 14' 44"} (Current)
MOON_B_DIST: 96.81 [deg]
ANNULUS_RA: 344.6931d {+22h 58m 46s} (J2000)
ANNULUS_DEC: -12.2244d {-12d 13' 27"}
ANNULUS_RADIUS: 74.510 [deg]
ANNULUS_WIDTH: 0.072 [deg] (Total width)
COMMENTS: GRB. SINGLE PULSE. COMPLEX. STARTS AT ABOUT T-10S.
COMMENTS: DURATION ABOUT 50S.
COMMENTS: VISIBLE ABOVE 300 KEV.
This IPN localization is preliminary. The "total width" of the annulus
was selected to include all known uncertainties and systematics. The final
analysis will reduce this width. All follow-up queries should be addressed to
Kevin Hurley (UC Berkeley, khurley@sunspot.ssl.berkeley.edu).
The center of the IPN annulus is tabulated below along the segment
that intersects the Huntsville error circle. The Distance column is
the sky-angle distance between the Huntville location and the sampled position
on the arc segment. The position of maximum probability plus
the 1-, 2-, & 3-sigma containment probabilities (statistical+systematic)
are marked.
A detailed description of the format, content, and meaning of this
document is given in the URL: http://gcn.gsfc.nasa.gov/gcn/ipn.html
(J2000)
RA DEC Distance
54.194 -80.169 4.88 <=== +3-sigma probability
54.347 -80.089 4.80
54.498 -80.009 4.71
54.649 -79.927 4.63
54.799 -79.844 4.54
54.948 -79.760 4.45
55.096 -79.675 4.36
55.243 -79.588 4.27
55.389 -79.501 4.18
55.535 -79.413 4.09
55.679 -79.323 4.00
55.823 -79.233 3.90
55.965 -79.141 3.81
56.106 -79.048 3.71
56.247 -78.954 3.61
56.386 -78.859 3.51
56.525 -78.763 3.42
56.662 -78.666 3.31
56.798 -78.567 3.21 <=== +2-sigma probability
56.933 -78.467 3.11
57.067 -78.366 3.01
57.200 -78.264 2.90
57.332 -78.161 2.79
57.463 -78.057 2.69
57.592 -77.951 2.58
57.720 -77.845 2.47
57.847 -77.737 2.36
57.973 -77.628 2.25
58.098 -77.518 2.13
58.222 -77.406 2.02
58.344 -77.294 1.91
58.465 -77.180 1.79
58.585 -77.065 1.67
58.703 -76.949 1.56 <=== +1-sigma probability
58.820 -76.832 1.44
58.936 -76.714 1.32
59.051 -76.594 1.20
59.164 -76.474 1.08
59.276 -76.352 0.96
59.387 -76.229 0.84
59.497 -76.105 0.72
59.605 -75.980 0.60
59.712 -75.853 0.49
59.817 -75.726 0.39
59.922 -75.597 0.31
60.025 -75.468 0.27
60.126 -75.337 0.29 <=== Max probability
60.226 -75.205 0.37
60.325 -75.073 0.47
60.423 -74.939 0.59
60.519 -74.804 0.71
60.614 -74.668 0.84
60.708 -74.531 0.97
60.800 -74.393 1.11
60.892 -74.254 1.25
60.981 -74.114 1.39
61.070 -73.973 1.53
61.157 -73.831 1.67 <=== -1-sigma probability
61.243 -73.688 1.81
61.327 -73.544 1.96
61.411 -73.400 2.10
61.493 -73.254 2.25
61.573 -73.107 2.40
61.653 -72.960 2.54
61.731 -72.812 2.69
61.808 -72.663 2.84
61.884 -72.513 3.00
61.958 -72.362 3.15
62.031 -72.210 3.30 <=== -2-sigma probability
62.104 -72.058 3.45
62.174 -71.905 3.61
62.244 -71.751 3.76
62.313 -71.596 3.92
62.380 -71.441 4.08
62.446 -71.285 4.23
62.511 -71.128 4.39
62.575 -70.971 4.55
62.637 -70.812 4.71
62.699 -70.654 4.87
62.760 -70.494 5.03 <=== -3-sigma probability
-------------------------------- THE END --------------------------------
Details of the content of the IPN_SEGMENT E-mail:
GCN/IPN/Huntsville GRB Location Notices
Ver: 10 Apr 95 SDB
Attached above is an example of a new capability of GCN.
GCN is distributing the GRB localizations determined by the
Interplanetary Network (IPN). Kevin Hurley is the PI for the IPN operation.
Since IPN localizations depend on the Ulysses spacecraft (and the GRO-BATSE
instrument), the time delays between the GRB and these notices will be
in the 1 to 3 day time range (when we eventually get all the procedures down).
Clearly, this is much different than the "few seconds" delays of the
BATSE-Original Notices, but the idea is to provide a global service
within the GCN network of sites and operations. This service will allow
for a more speedy analysis of the appropriate sub-region in observations
made by wide FOV instruments. Also, the already existing GCN distribution
network will allow for more timely follow-up observations by instruments that
have small FOVs (comparable to IPN arc segments). And in late '96, the IPN
network be able to produce small boxes, instead of annuli segments,
when the Russian Mars 96 spacecraft comes online.
The format of the GCN/IPN notices will be:
(1) A header of the pertinant numbers (in the standard GCN e-mail notice style)
suitable for easy parsing by programs. The GCN and HUNTSVILLE
locations of the GRB are given along with the angular distance between the two.
The Huntsville location is preliminary and may differ slightly from the "final"
location that will appear in the BATSE catalog. The position of the Sun & Moon
are given plus their separations from the GCN location as a reference
for optical observers. There are four fields for the IPN annulus:
the RA & Dec of the center of the annulus, the radius of it, and the total width
of the annulus.
(2) Some comments describing the status/accuracy of this localization and
any "special" comments on that specific burst.
(3) The arc segment in RA,Dec tabular form. The location along the arc segment
that has the maximum probablilty of the GRB location is marked. This position
is not a rigorous quantitative determination, but a determination made by a
human folding in the locations and sizes of the sizes of the BATSE-LOCBURST and
HUNTSVILLE error circles. While every effort will be made to choose this
location correctly, it should be used by observers only as a guide in making
their follow-up observations. Eventually, I would like to be able to mark
the table with plus and minus 3 sigma points which can also be used as a guide.
Down the road, it may be possible to distribute all of this location information
in graphical form via postscript files (or similar).
Fields Descriptions:
TITLE: GCN/IPN/HUNTSVILLE LOCALIZATION or
GCN/IPN LOCALIZATION
It depends on how much information went into the solution.
NOTICE_TYPE: Original or Final
The "Original" notices contain only the BATSE-Original location
and the 1-sec BATSE DISCLA data light curve to cross-
correlate witht he Ulysses lightcurve data.
At a later time, the finer time-resolution BATSE data is
available for the lightcurve cross-correlation and the
Huntsville BATSE team GRB location is available for
the "Final" notice.
TRIGGER_NUM: This is a number assigned by the on-board BATSE flight
software. It sequentially and uniquely identifies each
trigger.
DATE_TIME: The starting year/month/day hour:minute:second (UT)
of the GRB as determined by BATSE.
BACO_RA:
BACO_DEC: The BACODINE GRB RA & Dec location:
in decimal degrees; xxx.xx {0.00 to 359.99}
+/-xx.xx {-90.00 to +90.00}
The RA= HHh MMm SSs Dec= DDd MM' SS" format is included,
so that humans need not repeat a tedious calculation.
HUNT_RA:
HUNT_DEC: The Huntsville GRB location (Final notices only).
B_H_DELTA: The separation between the BACODINE & Huntsville locations.
(Final notices only).
HUNT_SC_AZ:
HUNT_SC_EL: The Huntsville location in GRB Spacecraft Az,El coordinates:
in decimal degrees; xxx.xx {0.00 to 359.99}.
in decimal degrees; +/-xx.xx {-90.00 to +90.00}.
The Zenith angle (90-El) is given as a convenience for the
two z-axis instruments.
(Final notices only).
SUN_POSTN:
SUN_B_DIST:
MOON_POSTN:
MOON_B_DIST: Sun & Moon Positions: There are four fields which give
the RA,Dec locations (current epoch) of the Sun & the Moon
and their angular distance from the burst location
(in decimal degrees). The Sun & Moon locations are also
given in HMS,d'" notation as well.
The Sun position is accurate to +/-0.01 deg.
The Moon location is accurate to +/-1 deg.
These fields are a convenience to the human recipients
who are planning follow-up observations.
ANNULUS_RA:
ANNULUS_DEC:
ANNULUS_RADIUS:
ANNULUS_WIDTH: The RA,Dec center of the IPN anulus:
in decimal degrees; xxx.xx {0.00 to 359.99}
+/-xx.xx {-90.00 to +90.00}
The RA= HHh MMm SSs Dec= DDd MM' SS" format is included.
The radius of the anulus in decimal degrees,
and the total width of the anulus; where total width means
that it is assigned to include statistical and all known
systematic errors.
COMMENTS: A brief description of the burst. It can be multiple lines.
Typically, the duration and something about the light curve
structure ("one peak", "multiple peaks", "FRED", etc).