TABLE OF CONTENTS:
The GCN system has been modified to incorporate the distribution
of high-significance Neutrino Transients detected by the SNEWS
world-wide system of neutrino detectors.
The neutrino transients are (a) the precursors to Type II supernovae, and
(b) possible precursors to collapsar-based GRBs.
There are currently 7 detectors in the SNEWS network: Super-Kamiokande, LVD, IceCube, KamLAND, Borexino, Daya Bay, HALO.
(SNEWS = SuperNova Early Warning System)
The SNEWS Transient detection program will trigger on time-correlated increases
in the event rate amongst 2 or more detectors in the network. SNEWS transmits the event to GCN.
If that transient meets the site's filtering criteria, then the site gets that Notice.
Like all the other sources of GRB and Transient information within the GCN system,
users can elect to receive (or not) this SNEWS Notice type.
The GCN/SNEWS Notices are archived within the GCN website
in the Table of SNEWS Notices.
Unlike all the other mission-specific table-pages, the table-page for the SNEWS Notice type
includes all the SNEWS_Test Notices. This inclusion is due to the fact
that the real-event Notices occurance rate is very low,
so there needs to be something else in this page to allow the community to more regularly monitor
the on-going status of the SNEWS-to-GCN connection (i.e. end2end status that things are working).
Notice Type, Occurance Rate, Content, and Purpose
There are 4 notice sub-types for SNEWS. They are the SNEWS_REAL and SNEWS_TEST sub-types
for each of the Coincidence and Individual sub-types:
Coincidence:
When two or more of the 7 neutrino detectors in the SNEWS network
has a temporal coincidence of clusters of neutrino detections in their detectors.
The coincidence is made with a 10-sec window.
Individual:
When an individual neutrino detector in the SNEWS network
has a high-confidence detection of 1 (or more) neutrinos.
These can contain (a) initial neutrino transient fluence information
along with the duration of that neutrino transient (time from the first neutrino to last neutrino detected),
and/or (b) updated information about the 'quality' of the detection.
The occurance rate on both sub-types (Coincidence and Individual) is very low: approximately 1 in 30 years (or fewer).
But they are of very high confidence level (>99% as determined by the SNEWS Team) and of high impact.
Location: At this time, of the 7 detectors in the SNEWS network, only the Super-K is capable of determining the direction of the neutrino(s) event.
If Super-K is one of the contributors, then the Notice will contain values in the RA,Dec,Error fields.
Else those fields are underfined.
The SNEWS_TEST Notice looks very much like a Real Event Notice.
Their purpose is to allow recipients sites to test their end of the operation
while waiting for the infrequent Real Notices.
They contain the RA,Dec location for the event detected by SNEWS.
They are generated (weekly, Tuesday at 12:00 US Eastern Time Zone) by the SNEWS team (not by GCN).
They also come in the 'coincidence' and 'individual' sub-type varietes.
Sequence of Activities and Time Delays
The sequence of activities for a typical transient is as follows:
1) Individual experiments detect neutrino event rate increase.
2) Individual experiments decide whether they have an event and
send a datagram to the SNEWS inter-detector correlation computer. (these are the "good" or "possible" notices.)
3) The central SNEWS computer compares the datagram time stamps and takes action
if there is a coincidence within 10 seconds.
Based on various quality criteria, coincidences (requiring at least two "good" notices in different detectors)
are automatically sent to the GCN computer.
4) Individual experiments can send "override" datagrams to the SNEWS computer after human-checking,
which will generate "individual" alerts without requiring a coincidence.
They can also issue their own alerts, with more information (e.g. pointing) if/when available.
5) If improved information becomes available, experiments may provide updates,
which will be automatically propagated by the SNEWS computer to the GCN computer.
The SNEWS-to-GCN-to-World Procedure:
GCN receives the SNEWS messages directly from the SNEWS inter-detector correlation computer,
reformats the messages into the standard GCN_Notice formats, and
distributes them to the sites using the usual distribution methods and filtering.
The total amount of time from the arrival of the neutrinos in the SNEWS detectors
to the GCN system is in the minutes to hours range.
Samples of the Full E-mail, Pager, Short-form Pager, & Subject-only
distribution methods of the GCN/SNEWS Notice are included below.
The format is very similar to the other spacecraft-instrument sources
of GRB/Transient locations -- the GCN-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 also appear in the email and pager formats.
The information is repeated (in the Misc section below) for the email-based recipients.
The SNEWS_Position Notice is type=149 (for all 4 sub-types).
Sites can elect to receive the SNEWS Notice type.
Only the Notice_Type and Delay filters are applicable to SNEWS notices.
See filtering to see which filter functions are applicable.
This filtering applies to all the existing distribution methods/media.
Only the Super-Kamiokande based events will have a RA,Dec location;
the 6 other detectors (scintillator-based) are nt able to determine direction of the neutrinos.
The location error for the Super-K events will be 5-10 deg (diameter) for a nearby supernova,
For the events from the 6 other detectors, the error field wil be set to 360deg.
The values specified are the diameter of the containment circle
at the specified % containment level. The values include
the statistical uncertainty and a systematic contribution.
There are 3 aspects of the SNEWS_TEST Notice type that are different from the other Test types within GCN:
1) The "test" form of this SNEWS type has the same type number (=149) as the real-transient
form of the Notice. This allows the user to receive them on the exact same "channel"
as the real notices. This was done because the occurance rate of the real notice
will be very rare (~1/30 yrs, or fewer). Keeping them the same type will allow the recipients
to test their response "pipelines" with higher end-to-end confidence.
(Having the Test Notice on a different type (ie the typical way for all the other GCN test types)
could well mean a bug could lie dormant in the real pipeline
and not be discovered until the moment of truth.)
2) They are generated by the SNEWS server; not the GCN server.
3) Their occurnace rates is once per week at a fixed time (12:00 US EST)
instead of the usual every ~3.7 hrs like all the other GCN Test types.
Sites are encouraged to acknowledge SNEWS and GCN in their publications
based on follow-up observations using these GCN/SNEWS locations.
For further information on this, please contact
Scott Barthelmy (for GCN-related issues),
Kate Scholberg , or
SNEWS Working Group (for SNEWS-specifc issues),
or see the
SNEWS web site,
and
these GCN web pages, and
GCN/SNEWS Transient table (includes the Test sub-type form of the SNEWS type).
Archiving
The GCN/SNEWS Notices are archived within the GCN website
in the Table of SNEWS Notices.
Please note that this table also contains the Test sub-type notices.
Field Descriptions:
The "trigger_num" is the uniquely identifying serial number
assigned by the SNEWS software to each trigger.
The "event_tjd" is the Truncated Julian Day of the trigger,
eg. TJD=17023 is 01 Jan 2015.
The "event_sod" is the UT seconds-of-day (SOD) of the trigger.
The units are seconds to two decimal places.
The "event_ra" & "event_dec" are the RA,Dec coordinates (J2000 epoch) of the trigger/event
as determined by the detector in the coincidence with the best directional information.
They are quantized at the 0.0001-degree level.
These two fields are undefined for any trigger that does not have Super-K as a contributor.
The "event_fluence" is actually the integrated fluence of the event
over the duration of the trigger. The units are counts (ie number of neutrinos).
If this is an 'individual' notice sub-type, then it is the number of neutrinos
detected in that detector. If it is a 'coincidence' sub-type, then it is
the number neutrinos detected by the first detector contributing to the coincidence.
More detailed information will be provided at snews.bnl.gov .
The "event_error" is the radius of the circle that will contain on average
"event_cont"% of the event locations.
The units are degrees to four decimal places.
The "event_cont" is the containment percentage for the quoted event_error value.
The units are percentage to two decimal places.
The "duration" is the time interval of the search window of the event_times stream
looking for an increase. The units are seconds, quantized at the 0.1 sec level.
For the "coincidence" sub-type, this will always be 10.0 sec;
and for the "individual" sub-type, it will be variable and will typically be the delta_time
between the first neutrino detected in that detector and the last detected;
each detector may have a different definition.
The "trigger_id" field contains bit_flags which attempt to identify
the type of transient event that triggered the SNEWS system.
The bit packing of the "trigger_id" entry in the packet is:
Bit_Number Item_name Description ---------- --------- ----------- 0 Sub-type Notice sub-type: 0=Individual, 1=Coincidence 1 Test Notice: 0=Real, 1=Test 2 Radec_undef RA,Dec knowledge: 0=Defined, 1=Undefined (no position known) 3-4 spare spare for future use 5 Retract 0=No or 1=Yes, it is definitely not a core-collapse supernova (a Retraction) 6-29 spare spare for future use 30 Test_submit 0=No or 1=Yes, this is a test submission (internal use only) 31 spare spare for future use
The "misc" field contains various bit_flags (ie which detectors contributed to the coincidence and.
if it was a 'possible' or 'good' contribution).
The bit packing is: Bit_Number Item_name Description ---------- --------- ----------- 0 Super-K_part Super-K contribution flag (aka 'participated') 1 Super-K_good Quality_factor is 'possible' 2 Super-K_poss Quality_factor is 'good' 3 Super-K_oride Quality_factor is 'override' 4 LVD_part LVD contribution flag 5 LVD_good Quality_factor is 'possible' 6 LVD_poss Quality_factor is 'good' 7 LVD_oride Quality_factor is 'override' 8 IceCube_part IceCube contribution flag 9 IceCube_good Quality_factor is 'possible' 10 IceCube_poss Quality_factor is 'good' 11 IceCube_oride Quality_factor is 'override' 12 KamLAND_part KamLAND contribution flag 13 KamLAND_good Quality_factor is 'possible' 14 KamLAND_poss Quality_factor is 'good' 15 KamLAND_oride Quality_factor is 'override' 16 Borexino_part Borexino instrument contribution flag 17 Borexino_good Quality_factor is 'possible' 18 Borexino_poss Quality_factor is 'good' 19 Borexino_oride Quality_factor is 'override' 20 Daya_Bay_part Daya Bay instrument contribution flag 21 Daya_Bay_good Quality_factor is 'possible' 22 Daya_Bay_poss Quality_factor is 'good' 23 Daya_Bay_oride Quality_factor is 'override' 24 HALO_part HALO instrument contribution flag 25 HALO_good Quality_factor is 'possible' 26 HALO_poss Quality_factor is 'good' 27 HALO_oride Quality_factor is 'override' 28 TBD_part TBD instrument contribution flag 29 TBD_good Quality_factor is 'possible' 30 TBD_poss Quality_factor is 'good' 31 TBD_oride Quality_factor is 'override' The 4 bits: a) The 'contribution' flag means that the detector contributed to the notice. b) The 'possible' flag means the burst observed by that detector was possibly real. c) The 'good' flag means the burst observed by that detector was very likely real. d) The 'override' flag means that the burst observed by that detector was human-checked and is real with extremely high confidence.
Examples of the SNEWS Notice type 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 Events.
While based on trial data from SNEWS,
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 are different for the real-vs-test notices.
The subject-line strings are (respectively):
GCN/SNEWS_POSITION_REAL
GCN/SNEWS_POSITION_TEST
And within the full e-mail format, the NOTICE_TYPE line can take on the following variations:
NOTICE_TYPE: REAL COINCIDENCE
NOTICE_TYPE: TEST COINCIDENCE
NOTICE_TYPE: REAL INDIVIDUAL
NOTICE_TYPE: TEST INDIVIDUAL
/////////////////////////SNEWS e-mail format//////////////////////////////
TITLE: GCN/SNEWS POSITION NOTICE
NOTICE_DATE: Sun 22 May 15 19:17:16 UT
NOTICE_TYPE: REAL COINCIDENCE
TRIGGER_NUM: 131
EVENT_RA: 273.34d {+18h 13m 22s} (J2000),
273.38d {+18h 13m 32s} (current),
272.98d {+18h 11m 54s} (1950)
EVENT_DEC: +44.60d {+44d 36' 06"} (J2000),
+44.60d {+44d 36' 13"} (current),
+44.59d {+44d 35' 11"} (1950)
EVENT_ERROR: 10.0 [deg radius, statistical plus systematic], 68.00% containment
EVENT_FLUENCE: 18 [neutrinos]
EVENT_TIME: 78275.83 SOD {21:44:35.83} UT
EVENT_DATE: 13501 TJD; 140 DOY; 05/05/22
EVENT_DUR: 10.00 [sec]
EXPT: Super-K Good, LVD Good, IceCube Possible, Daya_Bay Possible
SUN_POSTN: 185.38d {+12h 21m 31s} -2.33d {-02d 19' 37"}
SUN_DIST: 90.21 [deg]
MOON_POSTN: 139.61d {+09h 18m 25s} +20.44d {+20d 26' 41"}
MOON_DIST: 102.49 [deg]
GAL_COORDS: 72.06, 25.15 [deg] galactic lon,lat of the burst
ECL_COORDS: 276.35, 67.97 [deg] ecliptic lon,lat of the burst
COMMENTS: SNEWS Event Coordinates.
COMMENTS:
COMMENTS: This is a notification of a REAL COINCIDENCE event !!!
COMMENTS:
COMMENTS: For more information see: http://snews.bnl.gov
////////////////////////////////////////////////////////////////////////////
TITLE: GCN/SNEWS POSITION NOTICE
NOTICE_DATE: Sun 22 May 15 19:17:16 UT
NOTICE_TYPE: REAL COINCIDENCE
TRIGGER_NUM: 131
EVENT_RA: Undefined (J2000),
Undefined (current),
Undefined (1950)
EVENT_DEC: Undefined (J2000),
Undefined (current),
Undefined (1950)
EVENT_ERROR: 360.0 [deg radius, statistical plus systematic], 68.00% containment
EVENT_FLUENCE: 9 [neutrinos]
EVENT_TIME: 78275.83 SOD {21:44:35.83} UT
EVENT_DATE: 13501 TJD; 140 DOY; 05/05/22
EVENT_DUR: 10.00 [sec]
EXPT: LVD Good, IceCube Possible, Daya_Bay Possible
SUN_POSTN: 185.38d {+12h 21m 31s} -2.33d {-02d 19' 37"}
SUN_DIST: 90.21 [deg]
MOON_POSTN: 139.61d {+09h 18m 25s} +20.44d {+20d 26' 41"}
MOON_DIST: 102.49 [deg]
GAL_COORDS: 72.06, 25.15 [deg] galactic lon,lat of the burst
ECL_COORDS: 276.35, 67.97 [deg] ecliptic lon,lat of the burst
COMMENTS: SNEWS Event Coordinates.
COMMENTS:
COMMENTS: This is a REAL COINCIDENCE event !!!
COMMENTS:
COMMENTS: For more information see: http://snews.bnl.gov
////////////////////////////////////////////////////////////////////////////
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.
/////////////////////////SNEWS Pager format////////////////////////////// GCN/SNEWS REAL COINC RA=273.38d DEC=44.60d TIME: 21:44:35.83 UT I=18 [neutrinos] ERR=2.0deg /////////////////////////////////////////////////////////////////////////// GCN/SNEWS TEST COINC RA=273.38d DEC=44.60d TIME: 12:00:00.00 UT I=18 [neutrinos] ERR=2.0deg ///////////////////////////////////////////////////////////////////////////
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.
/////////////////////////SNEWS Short-Pager format/////////////////////////// SNEWS REAL COINC RA=272.98 DEC=44.59d ////////////////////////////////////////////////////////////////////////////
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:
/////////////////////////SNEWS Subject-only format/////////////////////////// [i need to fill in this example!!!] ///////////////////////////////////////////////////////////////////////////// [i need to fill in this example!!!] /////////////////////////////////////////////////////////////////////////////
/////////////////////////SNEWS TEST format///////////////////////////////////
TITLE: GCN/SNEWS POSITION NOTICE
NOTICE_DATE: Sun 22 May 15 19:17:16 UT
NOTICE_TYPE: TEST COINCIDENCE
TRIGGER_NUM: 132
EVENT_RA: 273.34d {+18h 13m 22s} (J2000),
273.38d {+18h 13m 32s} (current),
272.98d {+18h 11m 54s} (1950)
EVENT_DEC: +44.60d {+44d 36' 06"} (J2000),
+44.60d {+44d 36' 13"} (current),
+44.59d {+44d 35' 11"} (1950)
EVENT_ERROR: 2.0 [deg radius, statistical plus systematic], 68.00% containment
EVENT_FLUENCE: 18 [neutrinos]
EVENT_TIME: 43200.00 SOD {12:00:00.00} UT
EVENT_DATE: 13501 TJD; 140 DOY; 15/05/22
EVENT_DUR: 39.81 [sec]
EXPT: Detector_A Good, Detector_B Good, Detector_C Possible, Detector_D Good, Detector_E Good,
SUN_POSTN: 185.38d {+12h 21m 31s} -2.33d {-02d 19' 37"}
SUN_DIST: 90.21 [deg]
MOON_POSTN: 139.61d {+09h 18m 25s} +20.44d {+20d 26' 41"}
MOON_DIST: 102.49 [deg]
GAL_COORDS: 72.06, 25.15 [deg] galactic lon,lat of the event
ECL_COORDS: 276.35, 67.97 [deg] ecliptic lon,lat of the event
COMMENTS: SNEWS Event Coordinates.
COMMENTS:
COMMENTS: This is TEST notification -- it is NOT a real event.
COMMENTS:
COMMENTS: [whatever you want to put here; can be multiple lines]
COMMENTS: For more information see: http://snews.bnl.gov
/////////////////////////////////////////////////////////////////////////////
TITLE: GCN/SNEWS EVENT NOTICE
NOTICE_DATE: Sat 26 Sep 15 15:34:09 UT
NOTICE_TYPE: TEST COINCIDENCE
TRIGGER_NUM: 1000029
EVENT_RA: Undefined (J2000),
Undefined (current),
Undefined (1950)
EVENT_DEC: Undefined (J2000),
Undefined (current),
Undefined (1950)
EVENT_ERROR: 360.0 [deg radius, statistical plus systematic], 68.00% containment
EVENT_FLUENCE: 3 [neutrinos]
EVENT_TIME: 0.00 SOD {00:00:00.00} UT
EVENT_DATE: 16691 TJD; -331 DOY; 15/05/-331
EVENT_DUR: 0.00 [sec]
EXPT: Detector_A Good, Detector_B Possible, Detector_C Good, Detector_D Good,
SUN_POSTN: 182.97d {+12h 11m 52s} -1.28d {-01d 17' 04"}
SUN_DIST: Undefined [deg]
MOON_POSTN: 343.00d {+22h 52m 01s} -5.46d {-05d 27' 48"}
MOON_DIST: Undefined [deg]
MOON_ILLUM: 97 [%]
GAL_COORDS: Undefined,Undefined [deg] galactic lon,lat of the event
ECL_COORDS: Undefined,Undefined [deg] ecliptic lon,lat of the event
COMMENTS: SNEWS Event without RA,Dec coordinates.
COMMENTS: This is a Test COINCIDENCE notice.
COMMENTS:
COMMENTS: RA,Dec fields undefined.
COMMENTS: For more information see: http://snews.bnl.gov
/////////////////////////////////////////////////////////////////////////////