TABLE OF CONTENTS:
The GCN system has been modified to incorporate the distribution
of positions of GRBs, other unknown transients, and outbursts from known-sources
detected by the MAXI instrument on the ISS.
MAXI will detect about 1-2 "unknown source" transients per month,
and about 5 "known source" transients per month.
These detections are discovered during automated processing of the downlinked data.
They are sent to GCN and automatically distributed to those "sites" that have the respective types enabled
and that meet their filtering requirements.
The typical time delays range are a few hours (but occasionally can be as short as 20 min).
The typical position uncertainty of these detections is 0.5-1.0 deg radius (stat+sys, 90% containment).
All the GCN/MAXI Notices are archived within the GCN website in the Table of MAXI Transients.
Notice Types, Content, and Purpose
There are 3 GCN/MAXI Notice types. They are:
1) MAXI_UNKNOWN_SOURCE Notice contains detections that do not match anything in the catalogs.
These can be GRB or other x-ray/hard_x-ray transients that do not match known sources.
The Notices contain an RA,Dec location of a burst/transient;
the date, time, and trigger criteria (timescale and energy_band).
They occur at a rate of 18 per year.
Occaisionally, ~2-in-12 will have a possible known-source identification
attributed to the detection).
2) MAXI_KNOWN_SOURCE Notice contains detections of objects that are already in the catalogs.
The are outbursts from AGN, Nova-CVs, Supernova, and X-ray-stars.
The Notices contain an RA,Dec location of a known-source;
the date, time, and trigger criteria (timescale and energy_band).
They occur at a rate of ~70 per year.
(The X-ray stars subcategory has 95% of these "known" detetions,
and Nova-CVs has the other 5%. To date, there have ben no detections issued
by the MAXI Team in the AGN and Supernova subcategories.)
3) MAXI_Test Notice contains the RA,Dec location for the transient detected.
To allow sites to "practice" on MAXI Notices, there is the Test Notice.
It duplicates the MAXI_Unknown Notice Type in its content and format.
(Socket packet, email, and cell/page formats are all available).
Sites can elect to receive each of these Test Notices.
These Test Notices are issued every ~3.6 hours.
The RA,Dec positions rotate through a grid on the Northern and Southern celestial skies.
The automated ground software finds the transients and sends the message to GCN.
The timescales and localization precisions (radius, stat+sys, 90% containment)
of the various Notice types are as follows:
TIME SINCE LOCATION
TYPE TRIGGER ACCURACY COMMENTS
========= ============ ========== ========
MAXI_Unknown 200 min 1.0 deg No match-ups with anything in any of the catalogs
MAXI_Known 200 min 0.5 deg Matches something in a catalog (the 4 subcategories)
MAXI_Test n/a n/a Allows sites to periodically receive something to practice on
Samples of the E-mail, Cell/Pager, Short-form Cell/Pager, and Subject-only
distribution methods of the 3 GCN/MAXI Notice types are included below.
The format is very similar to the other spacecraft-instrument sources
of GRB and Transient locations -- the GCN-standard "TOKEN: value" format.
(Also available in XML format via email and sockets.)
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 cell/pager formats.
(Therefore, it is useful for email-based recipients to read the
socket packet definition document
to understand the contents of the email/cell/pager notifications are.)
The MAXI_Unknown_Source Notice is type=134;
the MAXI_Known_Source Notice is type=135;
the MAXI_Test Notice is type=136;
NUM TYPE VOEVENT SOCKET FullFmt_EMAIL PAGER/CELL XML
w/Txt (all 4 variants)
=== ============ ======= ====== ============= ================ ====
134 MAXI_Unknown Y P B B B&A
135 MAXI_Known Y P B B B&A
136 MAXI_Test Y P B B B&A
where:
Y = Also available in XML VOEvent format for XML_Sockets and VOEvent server sockets.
P = Packet (the GCN-standard 40 longword socket packet format)
B = Body of email (the GCN-standard "TOKEN: value" format)
A = As an attachment to a full-format email.
Sites can elect to receive each of the 3 MAXI Notice types on a Notice-by-Notice basis.
There is a separate dis/enable bit for each type.
See filtering to see which of the many other filter functions are applicable.
This filtering applies to all the existing distribution methods/media.
The uncertainty in the location will depend on:
(a) the transient_intensity and the instrumental background rate,
(b) the transient's position in the FOV, and
The error have been hardwired at:
1.0 deg (radius, 90% containment) for Unknown (Type=134) type, and
0.5 deg (radius, 90% containment) for Known (Type=135) type.
The errors quoted in the MAXI Notices includes both the statistical and systematic(TBC) contributions.
To allow sites to "practice" on MAXI Notices, there is the MAXI Test Notice type.
(Socket packet, email, and cell/page formats are all available).
Sites can elect to receive each of these Test Notices.
These Test Notices are issued every ~3.6 hours.
The RA,Dec positions rotate through a grid on the Northern and Southern celestial skies.
Sites are encouraged to acknowledge MAXI and GCN in their publications
based on follow-up observations using these GCN/MAXI locations.
For further information on this, please contact
Scott Barthelmy (for GCN issues),
or see the
MAXI (RIKEN/Japan site), and
MAXI (NASA site), and
and
these GCN web pages, and
GCN/MAXI GRB/Unknown_Transients table.
Examples of the 3 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):
GCN/MAXI_UNKNOWN
GCN/MAXI_KNOWN
/////////////////////////MAXI_Unknown e-mail format////////////////////////////
TITLE: GCN/MAXI NOTICE
NOTICE_DATE: Sat 24 Sep 11 21:51:02 UT
NOTICE_TYPE: MAXI Unknown Source Position
EVENT_ID_NUM: 28
EVENT_RA: 286.01d {+19h 04m 03s} (J2000),
286.19d {+19h 04m 46s} (current),
285.24d {+19h 00m 58s} (1950)
EVENT_DEC: -25.37d {-25d 22' 15"} (J2000),
-25.35d {-25d 21' 09"} (current),
-25.45d {-25d 26' 45"} (1950)
EVENT_ERROR: 1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX: 91.6 +- 12.2 [mCrab]
EVENT_DATE: 15823 TJD; 262 DOY; 11/09/19
EVENT_TIME: 59688.00 SOD {16:34:48.00} UT
EVENT_TSCALE: 1day
EVENT_EBAND: L+M, 2-10 keV
SUN_POSTN: 181.37d {+12h 05m 30s} -0.60d {-00d 35' 43"}
SUN_DIST: 103.10 [deg]
MOON_POSTN: 146.32d {+09h 45m 16s} +8.57d {+08d 33' 59"}
MOON_DIST: 138.34 [deg]
MOON_ILLUM: 9 [%]
GAL_COORDS: 11.25,-13.86 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 284.45, -2.73 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: MAXI Unknown Source Position. GRB or unknown X-ray Transient.
///////////////////////////////////////////////////////////////////////////////
/////////////////////////MAXI_Known e-mail format//////////////////////////////
TITLE: GCN/MAXI NOTICE
NOTICE_DATE: Mon 11 Apr 11 15:43:28 UT
NOTICE_TYPE: MAXI Known Source Position
EVENT_ID_NUM: 5660774400
SRC_RA: 171.28d {+11h 25m 06s} (J2000),
171.40d {+11h 25m 37s} (current),
170.71d {+11h 22m 51s} (1950)
SRC_DEC: -60.51d {-60d 30' 49"} (J2000),
-60.58d {-60d 34' 33"} (current),
-60.24d {-60d 14' 20"} (1950)
SRC_ERROR: 0.5 [deg radius, stat+sys, 90% containment]
SRC_FLUX: 340.0 [mCrab,2-20 keV]
SRC_DATE: 15660 TJD; 99 DOY; 11/04/09
SRC_TIME: 81047.00 SOD {22:30:47.00} UT
SRC_TSCALE: 4orbit
SRC_EBAND: L+M, 2-10 keV
SRC_CLASS: x-ray-star
SRC_NAME: Cen X-3
BAND_FLUX: 52.0, 13.0 [mCrab] (Src,Bkg: 2-4 keV)
BAND_FLUX: 119.0, 59.0 [mCrab] (Src,Bkg: 4-10 keV)
BAND_FLUX: 169.0,363.0 [mCrab] (Src,Bkg: 10-20 keV)
ISS_LON_LAT: 183.77,-30.72 [deg]
SUN_POSTN: 19.79d {+01h 19m 08s} +8.35d {+08d 20' 51"}
SUN_DIST: 123.65 [deg]
MOON_POSTN: 114.66d {+07h 38m 38s} +18.99d {+18d 59' 30"}
MOON_DIST: 91.65 [deg]
COMMENTS: MAXI Known Source Position.
///////////////////////////////////////////////////////////////////////////////
Examples of the (regular) cell/pager formats are shown below.
There are no "Subject" lines for these e-mails sent to the cell/pager companies
because the Subject line would use up valuable character counts
from the maximum displayable for the body of the message.
/////////////////////////Unknown Cell/Pager format//////////////////////////////// GCN/MAXI Unknown-src Position RA=123.522d DEC=-54.352d ERR=30.0arcmin T=18:35:24.00 UT I=21.0 [mCrab] /////////////////////////Known Cell/Pager format////////////////////////////////// GCN/MAXI Known-src Position RA=123.522d DEC=-54.352d ERR=30.0arcmin T=18:35:24.00 UT I=21.0 [mCrab] //////////////////////////////////////////////////////////////////////////////////
Examples of the short-form cell/pager format are shown below.
There are no "Subject" lines for these e-mails sent to the cell/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 cell/pager
method in the first place.
/////////////////////////Unknown Short-Cell/Pager format//////////////////////////// MAXI Unknown_src Position RA=123.139 DEC=-54.168d /////////////////////////Known Short-Cell/Pager format////////////////////////////// MAXI Known_src Position RA=123.139 DEC=-54.168d ////////////////////////////////////////////////////////////////////////////////////
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:
/////////////////////////Unknown Subject-only format//////////////////////////// Subject: MAXI RA=159.024 DEC=41.552d /////////////////////////Known Subject-only format////////////////////////////// Subject: MAXI RA=257.581 DEC=-38.125d //////////////////////////////////////////////////////////////////////////////// /////////////////////////Unknown Subject-only format//////////////////////////// Subject: MAXI RA=HH:MM:SS.S DEC=DD:MM:SS.S /////////////////////////Known Subject-only format////////////////////////////// Subject: MAXI RA=HH:MM:SS.S DEC=-DD:MM:SS.S ////////////////////////////////////////////////////////////////////////////////
Here is an example of the MAXI Test Notice (e_mail format).
////////////////////////////////MAXI_Test///////////////////////////////////////
TITLE: GCN/MAXI NOTICE
NOTICE_DATE: Thu 20 May 10 18:35:32 UT
NOTICE_TYPE: MAXI Test Position
EVENT_ID_NUM: 533526674
EVENT_RA: 123.46d {+08h 13m 50s} (J2000),
123.52d {+08h 14m 05s} (current),
123.14d {+08h 12m 33s} (1950)
EVENT_DEC: -54.32d {-54d 19' 14"} (J2000),
-54.35d {-54d 21' 09"} (current),
-54.17d {-54d 10' 04"} (1950)
EVENT_ERROR: 0.5 [deg radius, stat+sys, 90% containment]
EVENT_FLUX: 20.6 [mCrab,2-20 keV]
EVENT_TIME: 66924.00 SOD {18:35:24.00} UT
EVENT_DATE: 15336 TJD; 140 DOY; 10/05/20
BAND_FLUX: 25.5,12.7 [mCrab] (Src,Bkg: 2-4 keV)
BAND_FLUX: 11.4, 5.1 [mCrab] (Src,Bkg: 4-10 keV)
BAND_FLUX: 3.9, 2.4 [mCrab] (Src,Bkg: 10-20 keV)
ISS_LON_LAT: 183.77,-30.72 [deg]
SUN_POSTN: 57.44d {+03h 49m 45s} +20.07d {+20d 04' 16"}
SUN_DIST: 93.27 [deg]
MOON_POSTN: 147.80d {+09h 51m 11s} +9.18d {+09d 11' 02"}
MOON_DIST: 66.75 [deg]
COMMENTS: MAXI Test Position.
////////////////////////////////////////////////////////////////////////////////