TABLE OF CONTENTS:
The GCN/TAN system has been modified to incorporate the distribution
of positions of GRBs detected by the SuperAGILE instrument, and
detections and lightcurves by the MCAL instrument on the AGILE spacecraft.
About 5-10 times per year, there will be a GRB in the FOV (field of view)
of the SuperAGILE instrument that is bright enough to be localized.
AGILE transmits these localizations through the ORBCOMM system
to the ground within 30 min after the trigger.
The SuperAGILE team processes these messages and sends them to GCN/TAN.
If that burst position meets the site's filtering criteria, then it gets that Notice.
About 20 times per year a ground-based automatic search algorithm identifies
a GRB or GRBlike transient event among the on-board MCAL self-triggers,
and an AGILE_MCAL_ALERT Notice type is distributed.
Like all the other sources of GRB information within the GCN/TAN system,
users can elect to receive each of these SuperAGILE and MCAL Notice types.
The GCN/AGILE SuperAGILE Notices are archived within the GCN/TAN website in the Table of AGILE GRB Ground Notices.
The GCN/AGILE MCAL Notices are archived within the GCN/TAN website in the Table of AGILE MCAL Alert Notices.
Schedule: The distribution of AGILE_MCAL_ALERTs will begin in May 2019.
2) Notice Types, Content, and Purpose
There are 5 (3 burst-related + 1 transient-related + 1 test) SuperAGILE types,
1 AGILE spacecraft Notice type. and the 1 AGILE-MCAL Notice type.
They are:
2.1) Wakeup Position Notice contains the RA,Dec location for the burst detected by SuperAGILE.
They are issued 0 or 1 times per burst.
Since the Wakeup position is based on the least-possible amount of data in the processing
(just a small initial portion of the burst's lightcurve),
it has the lowest significance in the localization process. Even so,
the uncertainty in the position is ~30 arcmin for the bursts.
2.2) Ground Position Notice contains the RA,Dec location that has undergone
further automated analysis and processing on the ground.
They are issued 0 or 1 times per burst.
This reduces the location uncertainty range to 3 arcmin.
This downlinking and the automated processing means the total time delay is 1-2 hours.
2.3) Refined Position Notice And for some bursts, a third and final notice will be generated
when humans have gotten into the loop and made some improvement (refinement) into the location calculation.
The typical time delay ranges from 2 to 5 hours.
They are issued 0 or 1 times per burst (and on rare occaisions more than 1 per burst).
2.4) Transient Notice is identical in format and content to the GRB Position Notice
except that they contain RA,Dec locations of sources that are non-GRBs: Transients.
The occurrance rate of the Transient Notices is not yet detemined (it might be zero).
2.5) Pos_Test Notice is identical in format and content to the 3 Position Notices
except that the test notices contain computer-generated RA,Dec locations and all the other fields.
These test Notices are generated by the GCN/TAN computer every ~3.6 hrs.
They allow the receiving site to practice on the Position Notice types.
2.6) Pointing Direction -- DISCONTINUED
The AGILE spacecraft spends nearly all of the time in "stare" mode.
Every 14-30 days, AGILE starts a new "pointing session" by staring at a new region of the sky.
(On rare occaisions, the pointings can be as short as a couple days.)
But while it is "staring" during this pointing session, the spacecraft is slowly drifting
across the sky at a rate of about 1 deg per day. The Pointing Direction Notice
gives the instantaneous RA,Dec of the bore sight of the spacecraft, and it gives
the "start" and "end" times of the pointing session.
These Pointing Notices are generated every 8 hours.
2.7) MCAL Trigger Notice (Added May 2019) A GRB deposits in the MCAL Instrument.
The AGILE minicalorimeter (MCAL) is a non-imaging detector composed
of 30 CsI(Tl) scintillation bars, with a total on-axis geometrical
area of ~1400 cm^2, and sensitive in the 400 keV - 100 MeV energy range.
MCAL can self-trigger on transient events and acquire data, in an operational mode
managed by a fully configurable on-board trigger logic.
This trigger logic is based on the principle that a transient phenomenon produces
a count rate above a certain threshold over the background rate.
As the background strongly depends on energy and timescales, it is evaluated
by using different ratemeters (RMs), estimated on different
Search Integration Time (SIT) windows: these are handled by static hardware
logics (acting on 0.293 ms, 1 ms, and 16 ms timescales),
that impose a fixed threshold on the background rate, and by dynamic software logics
(acting on 64 ms, 256 ms, 1024 ms, and 8192 ms timescales),
that impose an adaptive threshold, dynamically evaluating the
background rate for each period of time.
On-board triggers can be issued due to transient events of astrophysical
(i.e., GRBs) or terrestrial (i.e., TGFs) nature, as well as spurious data
acquisitions due to detector intrinsic noise or charged particle background.
For this reason, an offline search algorithm is aimed at identifying
GRB and GRBlike transient events in the MCAL data, providing and
delivering a ALERT_MCAL_TRIGGER, in case of detection.
The AGILE MCAL ALERT notice type reports on events that trigger MCAL instrument on AGILE.
These notices alert the community on transient events that trigger the
AGILE MCAL on-board trigger logic in one or more predefined timescales
(i.e., sub-ms, 1 ms, 16 ms, 64 ms, 256 ms, 1024 ms, and 8192 ms), and are
successively selected and identified as GRBs by an offline burst search
algorithm that yields total significance values greater than 5 sigma.
The MCAL ALERT notice type contains: the trigger number, the date & time of the trigger,
the total counts in the pulse and in the peak and the significance in unit of sigma,
the background level, the trigger_time window (sub-ms to 8 sec) and the full integration time,
a url pointing to the lightcurve, the energy window, and the Lon, Lat of the spacecraft
at the time of the trigger.
As of 12-May-2020, there are 19 events in 11 months duration -- 1.7 evts/months.
The automated on-board SuperAGILE flight software
will generate GRB position notifications in real time.
(In addition, human-involved analyses of the data may sometimes result
in a revised position within a few hours after the burst.)
The timescales and localization precisions of the various Notice types are as follows:
TIME SINCE LOCATION
TYPE BURST PRECISION COMMENTS
========= ============ ========== ===================
Wakeup ~30 min ~30 arcmin On-board procesing
Ground 1-2 hrs 3 arcmin Ground processing
Refined ~2-5 hr 3 arcmin Humans in the loop
MCAL 40-130 min n/a Ground processing of the MCAL triggers
The sequence of activities for a typical burst follows:
1) The SuperAGILE instrument detects a burst (a trigger).
2) The Wakeup message is generated and transmitted.
3) Then after some ground processing, the Ground is generated and sent.
4) And finally, further ground processing (usually involving humans in the loop)
a Refined message is generated and sent.
The SuperAGILE-to-GCN/TAN-to-World Procedure:
All 3 types of SuperAGILE messages go through or originate in the SuperAGILE intrument operations
and are then set to GCN/TAN.
GCN/TAN reformats the messages into the standard GCN_Notice formats, and
distributes them to the sites using the usual distribution methods and filtering.
The additional time_delay for the GCN/TAN processing is never more than 0.2 sec.
Samples of the E-mail, Pager, Short-form Pager, and Subject-only distribution methods
of the 5 GCN/SuperAGILE Notice types are included below.
The format is very similar to the other spacecraft-instrument sources
of GRB locations -- the GCN/TAN-standard "TOKEN: value" format.
The socket packet contents and format are similar to the other mission-specific packet types
and are described in detail in the socket packet definition document.
This document also has explanations of the various fields in the packet (their content, values, and
implications for use), and those same fields are manifested in the email and pager formats.
(Therefore, it is useful for email/pager recipients to read the
socket packet definition document
to understand the contents of the email/pager notifications are.)
The Wakeup Position Notice is type=100;
the Ground Position Notice is type=101;
the Refined Position Notice is type=102.
the MCAL Notice is type=105.
The Position_Test Notice is type=109.
NUM TYPE SOCKET FullFmt_EMAIL PAGER/CELL_email XML
w/Txt (all 4 variants)
100 Wakeup_Pos P B B B&A
101 Ground_Pos P B B B&A
102 Refined_Pos P B B B&A
105 MCAL P B B B&A
107 Point_Dir P B B B&A
108 Pos_Transient P B B B&A
109 Pos_Test P B B B&A
where:
P = Packet (the GCN/TAN-standard 40 longword socket packet format)
B = Body of email (the GCN/TAN-standard "TOKEN: value" format)
A = As an attachment to a full-format email.
Sites can elect to receive each of the 5 SuperAGILE Notice types on a Type-by-Type basis.
There is a separate dis/enable bit for each type.
See filtering to see which filter functions are applicable.
This filtering applies to all the existing distribution methods/media.
The uncertainty in the location will depend on (a) the burst_intensity and (b) its position in the FOV.
The typical error is:
30 arcmin (diameter, 90% containment) for the Wake-up Position Notice,
3 arcmin (diameter, 90% containment) for Ground_Position and Refined_Position Notices.
The errors given in the Position Notices includes both the statistical contribution and
systematic contribution.
The MCAL Notice does not have position information (only temporal, lightcurve).
To allow sites to "practice" on SuperAGILE Notices, there is a SuperAGILE Test Notice.
The GRB_POS_TEST Notice duplicates the GRB_POS Notice (all socket packet, email, and cell/page formats).
Sites can elect to receive this Test Notice.
These Test Notices are issued every ~3.6 hours.
The RA,Dec positions rotate through a grid on the Northern & Southern celestial skies.
There is no "test" equivalent for the MCAL notice type.
The AGILE spacecraft pointing direction (ie FOV) is always known via the POINTING_DIR Notices.
It is therefore possible to minimize the slewing time of a ground-based telescope
by having it looking at the RA,Dec listed in the POINTING_DIR Notices.
Further, the telescope can continuously tile the FOV in a "patrol" mode
all night long thereby obtaining images just prior to the burst.
This is most suitable for automated systems.
Sites are encouraged to acknowledge SuperAGILE and GCN/TAN in their publications
based on follow-up observations using these GCN/SuperAGILE locations and MCAL triggers.
For further information on this, please contact
Scott Barthelmy (for GCN/TAN issues),
or see the
AGILE home, or
AGILE ASDC, and
and
these GCN/TAN web pages, and
GCN/AGILE GRB table.
GCN/AGILE GRB table (to start in May 2019).
Examples of the 5 Notice types of the e-mail formats are shown below. The "/////" divider bars are NOT part of the messages.
Do not take the actual values shown in these examples as real GRBs. While based on ground-test data from the mission, they have been adjusted to provide a broader representation of the various combinations of fields and value ranges.
For those sites/people that use demons and/or incoming e-mail filters,
the "Subject" lines for the all notice types are constant.
The subject-line strings are (respectively):
The Subject-lines are:
GCN/SuperAGILE_GRB_POSITION (the same for the 3 W/G/R Pos and Pos_Test Notices)
GCN/SuperAGILE_TRANSIENT_POSITION
GCN/AGILE_MCAL_TRIGGER
The 'misc' notices:
GCN/AGILE_POINTING_DIR
/////////////////////////Wakeup e-mail format/////////////////////////////
TITLE: GCN/SuperAGILE NOTICE
NOTICE_DATE: Sat 17 May 08 14:22:10 UT
NOTICE_TYPE: SuperAGILE GRB Wakeup Position
TRIGGER_NUM: 470
GRB_RA: 321.638d {+21h 26m 33s} (J2000),
321.738d {+21h 26m 57s} (current),
321.002d {+21h 24m 01s} (1950)
GRB_DEC: +1.788d {+01d 47' 17"} (J2000),
+1.822d {+01d 49' 21"} (current),
+1.571d {+01d 34' 14"} (1950)
GRB_ERROR: 30.00 [arcmin radius, statistical plus systematic]
GRB_INTEN: 2707.347 1383.584 [X & Y cnts]
GRB_SIGNIF: 16.50 12.15 [sigma]
GRB_DATE: 14467 TJD; 02 DOY; 08/01/02
GRB_TIME: 50795.30 SOD {14:06:35.30} UT
SUN_POSTN: 54.83d {+03h 39m 19s} +19.51d {+19d 30' 47"}
SUN_DIST: 92.30 [deg] Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN: 206.67d {+13h 46m 42s} -15.96d {-15d 57' 26"}
MOON_DIST: 114.57 [deg]
MOON_ILLUM: 95 [%]
GAL_COORDS: 54.83,-32.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 324.61, 15.98 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SuperAGILE GRB Coordinates.
COMMENTS: This is a GRB.
COMMENTS: SuperAGILE wake-up GRB coordinates
COMMENTS: SuperAGILE ground position will follow
//////////////////////////////////////////////////////////////////////////
/////////////////////////Ground e-mail format/////////////////////////////
TITLE: GCN/SuperAGILE NOTICE
NOTICE_DATE: Sat 17 May 08 15:17:39 UT
NOTICE_TYPE: SuperAGILE GRB Ground Position
TRIGGER_NUM: 474
GRB_RA: 321.638d {+21h 26m 33s} (J2000),
321.738d {+21h 26m 57s} (current),
321.002d {+21h 24m 01s} (1950)
GRB_DEC: +1.788d {+01d 47' 17"} (J2000),
+1.822d {+01d 49' 21"} (current),
+1.571d {+01d 34' 14"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical plus systematic]
GRB_INTEN: 2707.347 1383.584 [X & Y cnts]
GRB_SIGNIF: 16.50 12.15 [sigma]
GRB_DATE: 14467 TJD; 02 DOY; 08/01/02
GRB_TIME: 50795.30 SOD {14:06:35.30} UT
SUN_POSTN: 54.83d {+03h 39m 20s} +19.51d {+19d 30' 50"}
SUN_DIST: 92.31 [deg] Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN: 206.72d {+13h 46m 52s} -15.98d {-15d 58' 30"}
MOON_DIST: 114.53 [deg]
MOON_ILLUM: 95 [%]
GAL_COORDS: 54.83,-32.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 324.61, 15.98 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SuperAGILE GRB Coordinates.
COMMENTS: This is a GRB.
COMMENTS: SuperAGILE ground GRB coordinates
//////////////////////////////////////////////////////////////////////////
/////////////////////////Refined e-mail format////////////////////////////
TITLE: GCN/SuperAGILE NOTICE
NOTICE_DATE: Sat 17 May 08 17:38:47 UT
NOTICE_TYPE: SuperAGILE GRB Refined Position
TRIGGER_NUM: 475
GRB_RA: 321.638d {+21h 26m 33s} (J2000),
321.738d {+21h 26m 57s} (current),
321.002d {+21h 24m 01s} (1950)
GRB_DEC: +1.788d {+01d 47' 17"} (J2000),
+1.822d {+01d 49' 21"} (current),
+1.571d {+01d 34' 14"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical plus systematic]
GRB_INTEN: 2707.347 1383.584 [X & Y cnts]
GRB_SIGNIF: 16.50 12.15 [sigma]
GRB_DATE: 14467 TJD; 02 DOY; 08/01/02
GRB_TIME: 50795.30 SOD {14:06:35.30} UT
SUN_POSTN: 54.83d {+03h 39m 20s} +19.51d {+19d 30' 51"}
SUN_DIST: 92.31 [deg] Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN: 206.73d {+13h 46m 54s} -15.98d {-15d 58' 43"}
MOON_DIST: 114.52 [deg]
MOON_ILLUM: 95 [%]
GAL_COORDS: 54.83,-32.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 324.61, 15.98 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SuperAGILE GRB Coordinates.
COMMENTS: This is a GRB.
COMMENTS: SuperAGILE refined GRB coordinates
//////////////////////////////////////////////////////////////////////////
///////////////////////Trans e-mail format////////////////////////////////
TITLE: GCN/SuperAGILE NOTICE
NOTICE_DATE: Sat 17 May 08 14:27:39 UT
NOTICE_TYPE: SuperAGILE Transient Position
TRIGGER_NUM: 500
GRB_RA: 321.638d {+21h 26m 33s} (J2000),
321.738d {+21h 26m 57s} (current),
321.002d {+21h 24m 01s} (1950)
GRB_DEC: +1.788d {+01d 47' 17"} (J2000),
+1.822d {+01d 49' 21"} (current),
+1.571d {+01d 34' 14"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical plus systematic]
GRB_INTEN: 3707.347 2383.584 [X & Y cnts]
GRB_SIGNIF: 17.50 15.15 [sigma]
GRB_DATE: 14467 TJD; 02 DOY; 08/01/02
GRB_TIME: 50795.30 SOD {14:06:35.30} UT
SUN_POSTN: 54.83d {+03h 39m 20s} +19.51d {+19d 30' 50"}
SUN_DIST: 92.31 [deg] Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN: 206.72d {+13h 46m 52s} -15.98d {-15d 58' 30"}
MOON_DIST: 114.53 [deg]
MOON_ILLUM: 95 [%]
GAL_COORDS: 54.83,-32.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 324.61, 15.98 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SuperAGILE GRB Coordinates.
COMMENTS: This is a GRB.
COMMENTS: SuperAGILE ground GRB coordinates
///////////////////////////////////////////////////////////////////////
///////////////////////MCAL e-mail format////////////////////////////////
TITLE: GCN/AGILE-MCAL TRIGGER ALERT NOTICE
NOTICE_DATE: Thu 09 May 19 13:46:16 UT
NOTICE_TYPE: AGILE MCAL TRIGGER
TRIGGER_NUM: 480925310
GRB_DATE: 18571 TJD; 88 DOY; 19/03/29
GRB_TIME: 22910.66 SOD {06:21:50.66} UT
GRB_TOTAL_COUNTS: 113 [counts]
GRB_SIGNIF: 10.60 [sigma]
PEAK_COUNTS: 60 [counts]
PEAK_SIGNIF: 8.19 [sigma]
BACKGROUND: 21 [counts/0.032 sec]
DATA_TIME_SCALE: 0.032 [sec]
INTEG_TIME: 0.059 [sec]
SC_LON_LAT: 30.55,-2.03 [deg]
TRIGGER_LOGIC: '','','','64ms','','',''
ENERGY_RANGE: 400 - 100000 [keV]
LIGHT_CURVE: http://www.agilescienceapp.it/notices/GRB_061890_480925310.667604.png
COMMENTS: AGILE MCAL TRIGGER.
///////////////////////////////////////////////////////////////////////
Examples of the (regular) pager formats are shown below. There are no "Subject" lines for these 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.
[i need to fill in these examples!!!] /////////////////////////Pos Pager format////////////////////////////// /////////////////////////////////////////////////////////////////////// GCN/AGILE_MCAL Alert T=06:21:50.66 UT Burst_Cnts=113 [cnts] Burst_Signif=10.60 [sigma] ///////////////////////////////////////////////////////////////////////
Examples of the short-form pager format are shown below. There are no "Subject" lines for these 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.
[i need to fill in these examples!!!] /////////////////////////Pos Short-Pager format///////////////////////// //////////////////////////////////////////////////////////////////////// AGILE MCAL Alert T=06:21:50.66 UT Signif=10.60 UT ////////////////////////////////////////////////////////////////////////
There are two variations of the Subject-only format: decimal degrees (Current epoch)
and RA=hh:mm:ss Dec=DDdMMmSSs format (J2000 epoch). The two variations are shown below:
[i need to fill in these examples!!!] /////////////////////////Pos Subject-only format///////////////////////// ///////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////
Here is an example of the SuperAGILE Position Test Notice (e_mail format).
//////////////////////////////////////////////////////////////////////////////
TITLE: GCN/SuperAGILE NOTICE
NOTICE_DATE: Sat 19 Apr 08 19:01:07 UT
NOTICE_TYPE: SuperAGILE GRB Test Position
TRIGGER_NUM: 99999
GRB_RA: 0.000d {+00h 00m 00s} (J2000),
0.106d {+00h 00m 26s} (current),
-0.639d {-00h 02m 32s} (1950)
GRB_DEC: +35.000d {+35d 00' 00"} (J2000),
+35.046d {+35d 02' 46"} (current),
+34.722d {+34d 43' 18"} (1950)
GRB_ERROR: 5.00 [arcmin radius, statistical only]
GRB_INTEN: 1000.0 1234.5 [X & Y cnts]
GRB_SIGNIF: 12.34 11.44 [sigma]
GRB_DATE: 14575 TJD; 110 DOY; 08/04/19
GRB_TIME: 68459.00 SOD {19:00:59.00} UT
SUN_POSTN: 27.99d {+01h 51m 58s} +11.50d {+11d 30' 02"}
SUN_DIST: 34.55 [deg] Sun_angle= 1.9 [hr] (West of Sun)
MOON_POSTN: 199.44d {+13h 17m 45s} -12.82d {-12d 48' 55"}
MOON_DIST: 151.72 [deg]
MOON_ILLUM: 100 [%]
GAL_COORDS: 111.16,-26.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 15.56, 31.75 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SuperAGILE TEST Coordinates.
//////////////////////////////////////////////////////////////////////////////
Here is an example of the AGILE spacecraft Pointing Direction Notice (e_mail format).
//////////////////////////////////////////////////////////////////////////////
TITLE: GCN/AGILE NOTICE
NOTICE_DATE: Sun 22 Jun 08 16:01:20 UT
NOTICE_TYPE: AGILE Pointing Direction
CURR_POINT_RA: 323.248d {+21h 32m 59s} (J2000),
323.323d {+21h 33m 17s} (current),
322.807d {+21h 31m 14s} (1950)
CURR_POINT_DEC: +50.079d {+50d 04' 44"} (J2000),
+50.117d {+50d 07' 00"} (current),
+49.857d {+49d 51' 24"} (1950)
START_DATE: 14632 TJD; 167 DOY; 08/06/15
START_TIME: 43200.00 SOD {12:00:00.00} UT
END_DATE: 14647 TJD; 182 DOY; 08/06/30
END_TIME: 43200.00 SOD {12:00:00.00} UT
SUN_POSTN: 91.73d {+06h 06m 56s} +23.43d {+23d 25' 42"}
SUN_DIST: 93.46 [deg] Sun_angle= 8.6 [hr] (West of Sun)
MOON_POSTN: 318.16d {+21h 12m 38s} -16.48d {-16d 29' 01"}
MOON_DIST: 66.76 [deg]
MOON_ILLUM: 86 [%]
GAL_COORDS: 93.66, -1.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 354.75, 58.91 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: AGILE Pointing Direction.
COMMENTS: The SuperAGILE FOV is ~60deg diameter.
COMMENTS: The GRID instrument FOV is ~120deg diameter.
//////////////////////////////////////////////////////////////////////////////