RECENT DEVELOPMENTS:

March 2019:
This page has been changed from that for the original LIGO/Virgo O1 and O2 observing sessions, methods and formats
to their new O3 methods and formats; and GCN has changed to follow.

March 2019:
The LIGO-Virgo Collaboration has written a very thorough document on these 4 LVC Notices: LVC User Guide.
It has the full description of the LVC Notices, their content and use.

GCN/LVC Notices

TABLE OF CONTENTS:

  1. Introduction
  2. Notice types, Content, and Purpose
  3. S-series and MS-series Triggers
  4. Filtering S- vs MS-series Notices
  5. Time_Delays
  6. Sequence of Activities
  7. Retractions
  8. Formats
  9. Filtering
  10. Location Error
  11. Test Notices
  12. Observing Strategy
  13. Recognition
  14. Further Help
  15. E-mail Examples
  16. Cell/Pager Examples
  17. Short-form Cell/Pager Examples
  18. Subject-only Cell/Pager Examples
  19. VOEvent Example
  20. LVC Counterpart Notice Examples

Introduction

The GCN system distributes the G-W events (aka triggers) by the LIGO and Virgo instruments.

About 2(tbr) times a month, the LVC real-time pipelines will trigger (when there is sufficient enough signal)
and produce a series of LVC Notices (Preliminary, Initial, and Update).
All 3 Notice types will have maps giving the location probability of the event on the sky.
There is also a Retraction Notice when LIGO/Virgo have determied that the trigger is no longer astrophysical.

Like all the other sources of GRB/transient information within the GCN system,
users can elect to receive each of these LVC Notice types. LVC is now in a public phase of operations
and all Notices will be distributed to those sites requesting the LVC Notice types.

The LVC notices are archived at Table of LVC Events.
And the Circulars are archived at Circulars (includes LVC-related Circs).
New Circulars (on public LVC Notices) in ER13, ER14, and O3 are made public immediately,
and Circulars from past L-V GW events (during the O1 & O2 era) are made public once they have been published by the LVC.

Notice Types, Content, and Purpose

There are 5 (3 regular + 1 retraction + 1 counterpart) GCN/LVC Notice types.
They are:

1) Preliminary Notice starts the sequence of notices on any given trigger.
It contains the Trigger number, the type of trigger (CBC or Burst), the trigger date and time,
the parameters that characterise the trigger (and for Group=Burst: Fluence, Duration, and CentralFrequency)
as determined by the real-time LSC processing pipeline, the false alarm rate for a trigger of the same parameter values,
and a set of sky localization maps in FITS and PNG formats.
In the ER14 and O3 observing intervals these Notices come in two substreams:
S-series and MS-series (this replaces the G- and M-series of the O1 and O2 observing intervals).
The S-series (Super events) are real triggers, and the MS-series are Mock data challenge Superevent fake triggers.
For real triggers (S-series), there will typically be 1 Preliminary notices issued
(occaisionally, a second Preliminary is possible).
The first Preliminary Notice will be ~1-10 minute after the event.
There is no human-in-the-loop involvement in the processing of the real-time G-W data.

2) Initial Notice In 1-24 hours later, the Initial Notice is produced and distributed.
All the information and values are the same as the Prelimianry Notice, but including a location probability skymap
has been calculated and added. This map gives the probability that the GW event occured a given point on the sky
The Initial Notice contains a URL pointing to the map file (in HEALPIX FITS format).
This file can be retrieved from the LVC site, and then interrogated to guide your follow-up observations.
There is also a Retraction form of the Initial Notice. Retractions can be issued at any step in the processing.
These come in two substreams: S-series and MS-series. The S are real triggers, and the MS are Mock data challenge Superevent fake triggers.
There will be 1 to a few Initial Notices 1-6(tbr) hours after the event. They contain skymaps from more detailed/offline processing.
There is human-in-the-loop involvement reviewing the pipeline analysis to better determine if the trigger is a real G-W event.
This can result in a retraction of the triger (it is not a real G-W event), or an adjustment to the findings that go into the Initial Notices.

3) Update Notice In 1 to 7 days later, the Updated Notice will be produced and distributed.
And now the location probability map has been refined by doing the parameter estimation pipeline analysis.
The notice contains another url used to retrieve the refined map. It is also possible that the trigger will be retracted.
Retractions can be issued at any step in the processing.
An example of a Retraction is shown below
for the full-format email method.
Like the Preliminary and Initial, the Updates come in two substreams: S-series and MS-series.
There will be 1 to a few Update Notices issued from several to 24 hours after the event. They contain skymaps
from even more detailed and offline processing.
There is human-in-the-loop involvement reviewing the pipeline analysis, and adjusting the findings that go into the Update Notices.

4) Retraction Notice If, after human involvement in the data analaysis and evaulation, it is determined
that the event is no longer astrophysical, then a Retraction notice will be created and distributed.
Retractions can be issued at any step in the sequence of processing and sending out alerts.

5) Test Notice (the GCN-produced "test" notice) -- NO LONGER AVAILABLE (as of 28dec2018)
The Test Notice is partially the same format and content as the Initial/Update Notice types.
The Test notices are issued every ~4 hours covering a grid of locations roughly equally spaced
on the northern and southern hemispheres. These allow people/teams/instruments to practice operations.
Additionally for testing purposes, there will be 'role="test"' versions
of the Prelim/Initial/Update notices in the VOEvent XML format
intersperced amongst the 'role="observe"' notices.
This "Test" notice type has been superceeded by the "test" version issued by the L-V Team (the "MS"-series, see below).

6) LVC Counterpart Notice
This notice is produced by a follow-up observer that has identified a potential EM candidate
for the GW event. These contain the RA,Dec location of the candidate, the GW trigger ID,
the identity of the observer and the instrument/telescope used to make the follow-up observation,
the waveband of the observation, the duration, and the measured intenisty/flux/magnitude.
This LVC Counterpart notice is identical in format and content as the regular Counterpart notice;
but an LVC version was created to be used for LVC follow-ups during the proprietary period of LVC start-up operations.

S-series and MS-series Triggers

The PRELIMINARY, INITIAL, and UPDATE LVC Notices come in two sub-streams: The S-series and MS-series.
The S-series ("S' for Superevent) are the real triggers from the real-time low-latency pipelines looking for GW events.
The MS-series are the Mock data challenge Superevent fake triggers generated by an off-line program
that uses archival data that has been scrambled to have not science content whatsoever.
The purpose of the MS-series is to allow the recipient to do testing.
The expected occurance rate for the S-series real Binary Neutron Star tiggers is expect to be 1-50 per year (the prediction);
the MS-series come every 60 minutes (they come in pairs every 60 min; a PRELIMINARY & INITIAL pair or an PRELIMINARY & RETRACTION pair).
The S-series replaces the G-series (of the O1 & O2 era), and the MS-series replaces the M-series.

Filtering S- vs MS-series Notices:

Special filtering has been added to GCN to allow recipients
to select which substreams they want to receiver. In the recipient's configuration is a new field: "LVC_Enabled".
LVC_Enabled is a bitmask which takes on values of 0x200 for the S-series, 0x2000 for the MS-series,
Because it is a specialied filter function, it appears on the Configuration webform page in separate way;
it appears in the SIMBAD" column and allows the user two choice:
     a) receive the real/S-series only, or
     b) receive both the real/S-series and the test/MS-series.
There is no way (via the webform page) to receive the test/MS-series only -- if you want test-only, I can do that manually in 60 sec.
So LVC_Enable = 0x2200 means get both series, =0x200 means get only the S-series, and =0x2000 mean get only the MS-series.

Time Delays

The automated LVC pipelines will generate alert notifications in real time.
For the Preliminary Notice, it is all automated; there are no humans-in-the-loop. Latencies are 1-10 min. In addition, human-involved analyses of the data may sometimes result
in a revised position within a 4 to 24 hours latency after the trigger.)
The timescales and localization precisions of the 3 Notice types are as follows:

                 TIME SINCE    
TYPE             TRIGGER(tbr)   COMMENTS
=========        ============   ==========================================================================
LVC_PRELIMINARY  1-10 min       1st Notice, Timestamp Alert, location probability skymap; all automated processing.
LVC_INITIAL      4-24 hr        Improved SkyMap now available (human-involved procesing).
LVC_UPDATE       ~1-7 days      Ultimate refined skymap (more detailed off-line processing).
LVC_RETRACTION   1hr - 1day     After human analysis/evaluation, a retraction will be issued if trigger is not astrophysical.
=========        ============   ==========================================================================

Sequence of Activities

The sequence of activities for a typical burst follows:

For real triggers (S-series), there will typically be 1 (possibly 2) Preliminary notices issued.
The first will be 1-10 minutes after the event and contain date, time, param value, and a sky localization map.

There will be 1 to a few Initial Notices 1-6 hours after the event. They contain skymaps from more detailed/offline processing.

There will be 1 to a few Update Notices several to 24(tbr) hours after the event. They contain skymaps from even more detailed/offline processing.

There is a Sequence number associated with each series of Prelim/Initial/Update notices for a given event. It spans all 3 subtypes.
A sequence of Notices might look like:
     1-Preliminary,
     2-Initial,
     3-Update,
Or if there are two Preliminaries, then it would like:
     1-Preliminary,
     2-Preliminary,
     3-Initial,
     4-Update,
Sometimes there will be missing sequence numbers in those notices distributed,
because these "missing" notices have the "Internal" flag set to "1". Which means they were distributed to the LVC Team internally;
not to the public.

Anytime during this sequence a Retraction notice can be issued.
During O1 and O2, the retraction was a variation of the P/I/U types,
but in the ER14 and O3 operations era, the Retraction is its own separate type. The sequence of Notices might look like:
     1-Preliminary,
     2-Retraction.

The LVC-to-GCN-to-World Procedure:
Notices: GCN receives the LVC messages directly from the LVC real-time processing system,
converts the LVC VOEvent XML messages into all 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 LVC processing system to the output port on the GCN system is in the less than 1 sec.
Circulars: For each trigger, LVC team members respond (human-in-the-Loop)
to (a) determine if this trigger is real or not, (b) to provide any supporting information,
and (c) submit the circular ~2 to 24 hours after the trigger (for public distribution in the ER14/O3 era.
All these Circulars are stored in the public Circulars listing.

Follow-up observations: Using the information in the LVC Notices, follow-up observers
start making observations of the skymap regions. Their findings (candidates and upper limits)
can and should be published byt submitting in the LVC_COUNTERPART notices and LVC Circulars.

lvc notices and circ time sequence and ranges
NOTE: THIS FIGURE NEEDS ADJUSTMENT. THE TIMES WHEN the PRELIMINARY & INITIAL OCCUR NEEDS TO BE MOVED AND STRETCHED TO THE RIGHT.
The Prelim 1-10 minutes, and the Initial 1-12 hrs.

Retractions

In the notice sequence of Prelminary, Initial, and Update; a Retraction will be issued
if the ongoing processing (automated and human-in-the-loop) determines that the trigger
is no longer astrophysical in origin.

Formats

EMAIL-BASED: Samples of the E-mail, Cell/Pager, Short-form Cell/Pager, & Subject-only
distribution methods of the 5 GCN/LVC Notice types are included below.
The format is very similar to the other spacecraft-instrument sources
of GRB locations -- the GCN-standard "TOKEN: value" format.

SOCKET-BASED: The 160-byte binary 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 (Types 150-152,154,164).
This document also has explanations of the various fields in the packet
(their content, values, and implications for use).
and those same fields are appear in the email-based formats.
(Therefore, it is useful for email/cell/pager recipients to read the
socket packet definition document to understand the contents of the email/cell/pager/VOEvent notifications are.)

VOEVENT-BASED: Many of the XML voevent socket message contents are similar to the other mission-specific packet types;
are are totally unique given the unique nature of these GW events with respect to event types with GCN.
The user is encouraged to visit the LIGO/Virgo User Guide for detailed information about the content of these LVC notices,
particularly the Contents section.

NUM  TYPE             VOEVENT  SOCKET   EMAIL  EMAIL  EMAIL EMAIL  EMAIL  EMAIL  EMAIL  PAGER/CELL
                                        w/Txt  w/PS   w/GIF w/JPEG w/PDF  w/FITS        (all 4 variants)

150  Preliminary      Y        P        B+U                               n/a           B
151  Initial          Y        P        B+U                               n/a           B
152  Update           Y        P        B+U                               n/a           B
154  Counterpart      Y        P        B                                               B
164  Retraction       Y        P        B                                               B

where:
Y = Available in XML VOEvent format for XML_Sockets and VOEvent server sockets.
P = Packet (the GCN-standard 160-byte socket packet format).
B = Body of email (the GCN-standard "TOKEN: value" format).
U = URL (the URL is contained in the packet and the body of the email).
A = Attachment (the actual data product is optionally attached to the email).

Filtering

Sites can elect to receive each of the 4 LVC Notice types on a type-by-type 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.

See the description of the specialized filtering for the S- and MS-series Notices above.

Location Errors

The uncertainty in the location will depend on:
(a) the number of GW detectors that contributed to the trigger (2 or 3),
(b) the masses of the compact objects involved, and
(c) the duration of the GW event.
For BNS events, the median localization accuracy of in terms of the 90% credible area will be 120–180 deg2.
12–21% of BNS mergers will be localized to less than 20 deg2. The shape is tpically circular for 3-GW_detector events.
The typical sizes of these regions for 2-GW_detector triggers iss 500 - 1000 deg2. They are banana shaped.

Test Notices

The MS-series of notices are the test notices. To allow sites to "practice" on LVC Notices.
It mimics the LVC_PRELIMINARY/_INITIAL/_UPDATE Notice types (in all the socket packet, VOEvent,
email, and cell/pager formats). These Test Notices are issued every 60 minutes.
Sites can elect to receive these Test Notices.
(The MS-series replaces the explicit LVC_TEST notice (type=153) o the O1/O2 era.)

Observing Strategy

These GW detectors are essentially omni-directional. As such, the detections
will be from sources uniformly distributed across the 4pi of the sky.
Since very few follow-up instruments cannot cover these large patches on the sky (10x10 to 10x90deg) in a single fr few observations,
a common follow-up approach will be to observe the galaxies that are located in the regions of high probability.

Recognition

During the Public phase, sites are encouraged to acknowledge LVC in their publications
based on follow-up observations using these LVC locations.

Further Help

For further information on this, please contact
Scott Barthelmy (for GCN issues),
or see the LVC LV-EM Techinical Information,
or see the LVC LV-EM Follow-Up Tutorial,
and
these GCN web pages, and
GCN/Swift GRB table.


E-mail Examples

Examples of the 4 Notice types of the e-mail formats are shown below.
The "/////" divider bars are NOT part of the messages.

Note that the usual fields (SUN_POSTN, SUN_DIST, MOON_POSTN, MOON_DIST, MOON_ILLUM,
GAL_CCORDS, and ECL_COORDS) that are in all the GCN e-mail notice formats are not present
in the LVC PRELIMINARY, INITIAL, and UPDATE notices, because these are meaningless quantities
for an event, that at this stage, has an error region covering 100's of degrees.
The LVC_COUNTERPART notice does have the observer-support fields, because at this stage
of the observations sequence, the error boxes are now down to less than one degree.

Do not take the actual values shown in these examples as real GW events.
While based on data from a run back in 2010, they are not real triggers.

For those sites/people that use demons and/or incoming e-mail filters (e.g. procmail),
the "Subject" lines for the all notice types are constant.
The subject-line strings are (respectively):
The 'raw' versions:
GCN/LVC_PRELIMINARY
GCN/LVC_INITIAL
GCN/LVC_UPDATE
GCN/LVC_RETRACTION
GCN/LVC_COUNTERPART
Note that LVC has changed the content of their notices (from the O1/O2 era to the ER13-14/O3 era (Feb 2019)).
Note that only MS-series examples are shown below; they are identical to the S-series, just replace "MS" with "S" in the 5 places in the notices:

//////////////////////// Preliminary e-mail format ////////////////////////////////
TITLE:            GCN/LVC NOTICE
NOTICE_DATE:      Wed 13 Mar 19 17:59:21 UT
NOTICE_TYPE:      TEST LVC Preliminary
TRIGGER_NUM:      MS190313w
TRIGGER_DATE:     18555 TJD;    72 DOY;   2019/03/13 (yyyy/mm/dd)
TRIGGER_TIME:     64335.018661 SOD {17:52:15.018661} UT
SEQUENCE_NUM:     1
GROUP_TYPE:       1 = CBC
SEARCH_TYPE:      6 = MockDataChallenge
PIPELINE_TYPE:    4 = GSTLAL
FAR:              9.112e-14 [Hz]  (one per 127024138.3 days)  (one per 348011.34 years)
PROB_NS:          1.00 [range is 0.0-1.0]
PROB_REMNANT:     1.00 [range is 0.0-1.0]
PROB_BNS:         0.99 [range is 0.0-1.0]
PROB_NSBH:        0.00 [range is 0.0-1.0]
PROB_BBH:         0.00 [range is 0.0-1.0]
PROB_TERRES:      0.00 [range is 0.0-1.0]
TRIGGER_ID:       0x12
MISC:             0x1C9DC03
SKYMAP_FITS_URL:  https://gracedb.ligo.org/api/superevents/MS190313w/files/bayestar.fits.gz
EVENTPAGE_URL:    https://gracedb.ligo.org/superevents/MS190313w/view/
COMMENTS:         LVC Preliminary Trigger Alert.
COMMENTS:
COMMENTS:         NOTE: This is a TEST.  The 'role' was test in the original voevent.
COMMENTS:
COMMENTS:         This event is an OpenAlert.
COMMENTS:         LIGO-Hanford Observatory contributed to this candidate event.
COMMENTS:         LIGO-Livingston Observatory contributed to this candidate event.
COMMENTS:         This is an MS-series trigger (MS is for Mock Super Event).
//////////////////////// Initial e-mail format ////////////////////////////////////
TITLE:            GCN/LVC NOTICE
NOTICE_DATE:      Wed 13 Mar 19 18:01:01 UT
NOTICE_TYPE:      TEST LVC Initial Skymap
TRIGGER_NUM:      MS190313w
TRIGGER_DATE:     18555 TJD;    72 DOY;   2019/03/13 (yyyy/mm/dd)
TRIGGER_TIME:     64335.018661 SOD {17:52:15.018661} UT
SEQUENCE_NUM:     2
GROUP_TYPE:       1 = CBC
SEARCH_TYPE:      6 = MockDataChallenge
PIPELINE_TYPE:    4 = GSTLAL
FAR:              9.112e-14 [Hz]  (one per 127024138.3 days)  (one per 348011.34 years)
PROB_NS:          1.00 [range is 0.0-1.0]
PROB_REMNANT:     1.00 [range is 0.0-1.0]
PROB_BNS:         0.99 [range is 0.0-1.0]
PROB_NSBH:        0.00 [range is 0.0-1.0]
PROB_BBH:         0.00 [range is 0.0-1.0]
PROB_TERRES:      0.00 [range is 0.0-1.0]
TRIGGER_ID:       0x12
MISC:             0x2C9DE03
SKYMAP_FITS_URL:  https://gracedb.ligo.org/api/superevents/MS190313w/files/bayestar.fits.gz
EVENTPAGE_URL:    https://gracedb.ligo.org/superevents/MS190313w/view/
COMMENTS:         LVC Super Initial Skymap -- a location probability map.
COMMENTS:
COMMENTS:         NOTE: This is a TEST.  The role was test in the original voevent.
COMMENTS:
COMMENTS:         This event is an OpenAlert.
COMMENTS:         LIGO-Hanford Observatory contributed to this candidate event.
COMMENTS:         LIGO-Livingston Observatory contributed to this candidate event.
COMMENTS:         This is an MS-series trigger (MS is for Mock Super Event).
//////////////////////// Update e-mail format /////////////////////////////////////
Eventually they will have an Update to use as an example of an UPDATE.


//////////////////////// RETRACTION e-mail format ////////////////////////////////
TITLE:            GCN/LVC_RETRACTION NOTICE
NOTICE_DATE:      Wed 13 Mar 19 12:39:02 UT
NOTICE_TYPE:      LVC Retraction
TRIGGER_NUM:      MS190313o
TRIGGER_DATE:     18555 TJD;    72 DOY;   2019/03/13 (yyyy/mm/dd)
TRIGGER_TIME:     45206.796455 SOD {12:33:26.796455} UT
SEQUENCE_NUM:     2
TRIGGER_ID:       0x32
MISC:             0x2C9BF00
COMMENTS:         LVC Retraction of a previous Alert.
COMMENTS:
COMMENTS:         NOTE: This is a TEST.  The 'role' was test in the original voevent.
COMMENTS:
COMMENTS:
COMMENTS:         NOTE: This is a RETRACTION.  The trigger is no longer considered to be astrophysical in origin.
COMMENTS:                                      As such, many of the parameters have bogus/undefined values.
COMMENTS:         This event is an OpenAlert.
COMMENTS:         This is an MS-series trigger (MS is for Mock Super Event).
//////////////////////// Counterpart e-mail format ////////////////////////////////
See at end of this webpage.
///////////////////////////////////////////////////////////////////////////////////

Cell/Pager Examples

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.

///////////////////////// Preliminary Cell/Pager format ///////////////////////////
GCN/LVC Prelim
T=16:33:15.00 UT
TRIGGER_NUM=S131211ab
GROUP=CBC
FAR=1.234e-07 [Hz]
PROB_NS:      0.90 [0.0-1.0]
PROB_REMNANT: 1.00 [0.0-1.0]
PROB_BNS:     0.27 [0.0-1.0]
PROB_NSBH:    0.26 [0.0-1.0]
PROB_BBH:     0.24 [0.0-1.0]
PROB_TERRES:  0.23 [0.0-1.0]
HardwareInjection
Vetted-by-a-human
OpenAlert
///////////////////////// Initial Cell/Pager format ///////////////////////////////
GCN/LVC Initial Event
T=16:33:15.00 UT
TRIGGER_NUM=S131211ab
GROUP=CBC
FAR=1.234e-07 [Hz]
PROB_NS:      0.90 [0.0-1.0]
PROB_REMNANT: 1.00 [0.0-1.0]
PROB_BNS:     0.27 [0.0-1.0]
PROB_NSBH:    0.26 [0.0-1.0]
PROB_BBH:     0.24 [0.0-1.0]
PROB_TERRES:  0.23 [0.0-1.0]
HardwareInjection
Vetted-by-a-human
OpenAlert
///////////////////////// Update Cell/Pager format ////////////////////////////////
GCN/LVC Update Event
T=16:33:16.00 UT
TRIGGER_NUM=S131211ab
GROUP=CBC
FAR=1.234e-07 [Hz]
PROB_NS:      0.90 [0.0-1.0]
PROB_REMNANT: 1.00 [0.0-1.0]
PROB_BNS:     0.27 [0.0-1.0]
PROB_NSBH:    0.26 [0.0-1.0]
PROB_BBH:     0.24 [0.0-1.0]
PROB_TERRES:  0.23 [0.0-1.0]
HardwareInjection
Vetted-by-a-human
OpenAlert
///////////////////////// Retraction Cell/Pager format ////////////////////////////

///////////////////////// Counterpart Cell/Pager format ///////////////////////////
See at end of this webpage.
///////////////////////////////////////////////////////////////////////////////////

Short-form Cell/Pager Examples

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.

///////////////////////// Preliminary Short-Cell/Pager format /////////////////////
LVC Prelim
T=16:33:15.00 UT
TRIG_NUM=S131211ab
///////////////////////// Initial Short-Cell/Pager format /////////////////////////
#LVC Initial
#T=12:25:21.00 UT
#TRIG_NUM=M169734
///////////////////////// Update Short-Cell/Pager format //////////////////////////
LVC Update
T=16:33:16.00 UT
TRIG_NUM=S131211ab
///////////////////////// Retraction Short-Cell/Pager format //////////////////////
LVC Update
T=16:33:16.00 UT
TRIG_NUM=S131211ab
///////////////////////// Counterpart Short-Cell/Pager format /////////////////////
See at end of this webpage.
///////////////////////////////////////////////////////////////////////////////////


Subject-only Examples

Normally for GCN Notices, there are two variations of the Subject-only format:
decimal degrees (Current epoch), and
RA=hh:mm:ss Dec=DDdMMmSSs format (J2000 epoch).
But since the LVC Notices do not have a well located event position -- rather a large error region --
the TriggerTime was incorporated into the Subject-line in place of the RA,Dec.

///////////////////////// Prelminary Subject-only format //////////////////////////
LVC Prelim T=16:33:15.00 UT
///////////////////////// Initial Subject-only format /////////////////////////////
LVC Initial T=16:33:15.00 UT
///////////////////////// Update Subject-only format //////////////////////////////
LVC Update T=16:33:16.00 UT
///////////////////////// Retraction Subject-only format //////////////////////////
LVC Retraction T=16:33:16.00 UT
///////////////////////// Counterpart Subject-only format /////////////////////////
See at end of this webpage.
///////////////////////////////////////////////////////////////////////////////////


VOEvent Notice Examples

Here are examples of the LVC Notices (VOEvent format).

//////////////////////// LVC Preliminary voevent format ////////////////////////////////
<?xml version="1.0" ?> <voe:VOEvent xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:voe="http://www.ivoa.net/xml/VOEvent/v2.0" xsi:schemaLocation="http://www.ivoa.net/xml/VOEvent/v2.0 http://www.ivoa.net/xml/VOEvent/VOEvent-v2.0.xsd" version="2.0" role="test" ivorn="ivo://gwnet/LVC#MS190313w-1-Preliminary"> <Who> <Date>2019-03-13T17:59:19</Date> <Author> <contactName>LIGO Scientific Collaboration and Virgo Collaboration</contactName> </Author> </Who> <What> <Param name="Packet_Type" dataType="int" value="150"> <Description>The Notice Type number is assigned/used within GCN, eg type=150 is an LVC_PRELIMINARY notice</Description> </Param> <Param name="internal" dataType="int" value="0"> <Description>Indicates whether this event should be distributed to LSC/Virgo members only</Description> </Param> <Param name="Pkt_Ser_Num" dataType="string" value="1"> <Description>A number that increments by 1 each time a new revision is issued for this event</Description> </Param> <Param name="GraceID" dataType="string" value="MS190313w" ucd="meta.id"> <Description>Identifier in GraceDB</Description> </Param> <Param name="AlertType" dataType="string" value="Preliminary" ucd="meta.version"> <Description>VOEvent alert type</Description> </Param> <Param name="HardwareInj" dataType="int" value="0" ucd="meta.number"> <Description>Indicates that this event is a hardware injection if 1, no if 0</Description> </Param> <Param name="OpenAlert" dataType="int" value="1" ucd="meta.number"> <Description>Indicates that this event is an open alert if 1, no if 0</Description> </Param> <Param name="EventPage" dataType="string" value="https://gracedb.ligo.org/superevents/MS190313w/view/" ucd="meta.ref.url"> <Description>Web page for evolving status of this GW candidate</Description> </Param> <Param name="Instruments" dataType="string" value="H1,L1" ucd="meta.code"> <Description>List of instruments used in analysis to identify this event</Description> </Param> <Param name="FAR" dataType="float" value="9.11069936486e-14" ucd="arith.rate;stat.falsealarm" unit="Hz"> <Description>False alarm rate for GW candidates with this strength or greater</Description> </Param> <Param name="Group" dataType="string" value="CBC" ucd="meta.code"> <Description>Data analysis working group</Description> </Param> <Param name="Pipeline" dataType="string" value="gstlal" ucd="meta.code"> <Description>Low-latency data analysis pipeline</Description> </Param> <Param name="Search" dataType="string" value="MDC" ucd="meta.code"> <Description>Specific low-latency search</Description> </Param> <Group type="GW_SKYMAP" name="bayestar"> <Param name="skymap_fits" dataType="string" value="https://gracedb.ligo.org/api/superevents/MS190313w/files/bayestar.fits.gz" ucd="meta.ref.url"> <Description>Sky Map FITS</Description> </Param> </Group> <Group type="Classification"> <Param name="BNS" dataType="float" value="0.990715890043" ucd="stat.probability"> <Description>Probability that the source is a binary neutron star merger (both objects lighter than 3 solar masses)</Description> </Param> <Param name="NSBH" dataType="float" value="0.0" ucd="stat.probability"> <Description>Probability that the source is a neutron star-black hole merger (primary heavier than 5 solar masses, secondary lighter than 3 solar masses)</Description> </Param> <Param name="BBH" dataType="float" value="0.0" ucd="stat.probability"> <Description>Probability that the source is a binary black hole merger (both objects heavier than 5 solar masses)</Description> </Param> <Param name="MassGap" dataType="float" value="0.0" ucd="stat.probability"> <Description>Probability that the source has at least one object between 3 and 5 solar masses</Description> </Param> <Param name="Terrestrial" dataType="float" value="0.00928410995716" ucd="stat.probability"> <Description>Probability that the source is terrestrial (i.e., a background noise fluctuation or a glitch)</Description> </Param> <Description>Source classification: binary neutron star (BNS), neutron star-black hole (NSBH), binary black hole (BBH), MassGap, or terrestrial (noise)</Description> </Group> <Group type="Properties"> <Param name="HasNS" dataType="float" value="1.0" ucd="stat.probability"> <Description>Probability that at least one object in the binary has a mass that is less than 2.83 solar masses</Description> </Param> <Param name="HasRemnant" dataType="float" value="1.0" ucd="stat.probability"> <Description>Probability that a nonzero mass was ejected outside the central remnant object</Description> </Param> <Description>Qualitative properties of the source, conditioned on the assumption that the signal is an astrophysical compact binary merger</Description> </Group> </What> <WhereWhen> <ObsDataLocation> <ObservatoryLocation id="LIGO Virgo"/> <ObservationLocation> <AstroCoordSystem id="UTC-FK5-GEO"/> <AstroCoords coord_system_id="UTC-FK5-GEO"> <Time> <TimeInstant> <ISOTime>2019-03-13T17:52:15.018661</ISOTime> </TimeInstant> </Time> </AstroCoords> </ObservationLocation> </ObsDataLocation> </WhereWhen> <How> <Description>Candidate gravitational wave event identified by low-latency analysis</Description> <Description>H1: LIGO Hanford 4 km gravitational wave detector</Description> <Description>L1: LIGO Livingston 4 km gravitational wave detector</Description> </How> <Description>Report of a candidate gravitational wave event</Description> </voe:VOEvent>

//////////////////////// LVC Initial voevent format ////////////////////////////////////
<?xml version="1.0" ?> <voe:VOEvent xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:voe="http://www.ivoa.net/xml/VOEvent/v2.0" xsi:schemaLocation="http://www.ivoa.net/xml/VOEvent/v2.0 http://www.ivoa.net/xml/VOEvent/VOEvent-v2.0.xsd" version="2.0" role="test" ivorn="ivo://gwnet/LVC#MS190313w-2-Initial"> <Who> <Date>2019-03-13T18:00:58</Date> <Author> <contactName>LIGO Scientific Collaboration and Virgo Collaboration</contactName> </Author> </Who> <What> <Param name="Packet_Type" dataType="int" value="151"> <Description>The Notice Type number is assigned/used within GCN, eg type=151 is an LVC_INITIAL notice</Description> </Param> <Param name="internal" dataType="int" value="0"> <Description>Indicates whether this event should be distributed to LSC/Virgo members only</Description> </Param> <Param name="Pkt_Ser_Num" dataType="string" value="2"> <Description>A number that increments by 1 each time a new revision is issued for this event</Description> </Param> <Param name="GraceID" dataType="string" value="MS190313w" ucd="meta.id"> <Description>Identifier in GraceDB</Description> </Param> <Param name="AlertType" dataType="string" value="Initial" ucd="meta.version"> <Description>VOEvent alert type</Description> </Param> <Param name="HardwareInj" dataType="int" value="0" ucd="meta.number"> <Description>Indicates that this event is a hardware injection if 1, no if 0</Description> </Param> <Param name="OpenAlert" dataType="int" value="1" ucd="meta.number"> <Description>Indicates that this event is an open alert if 1, no if 0</Description> </Param> <Param name="EventPage" dataType="string" value="https://gracedb.ligo.org/superevents/MS190313w/view/" ucd="meta.ref.url"> <Description>Web page for evolving status of this GW candidate</Description> </Param> <Param name="Instruments" dataType="string" value="H1,L1" ucd="meta.code"> <Description>List of instruments used in analysis to identify this event</Description> </Param> <Param name="FAR" dataType="float" value="9.11069936486e-14" ucd="arith.rate;stat.falsealarm" unit="Hz"> <Description>False alarm rate for GW candidates with this strength or greater</Description> </Param> <Param name="Group" dataType="string" value="CBC" ucd="meta.code"> <Description>Data analysis working group</Description> </Param> <Param name="Pipeline" dataType="string" value="gstlal" ucd="meta.code"> <Description>Low-latency data analysis pipeline</Description> </Param> <Param name="Search" dataType="string" value="MDC" ucd="meta.code"> <Description>Specific low-latency search</Description> </Param> <Group type="GW_SKYMAP" name="bayestar"> <Param name="skymap_fits" dataType="string" value="https://gracedb.ligo.org/api/superevents/MS190313w/files/bayestar.fits.gz" ucd="meta.ref.url"> <Description>Sky Map FITS</Description> </Param> </Group> <Group type="Classification"> <Param name="BNS" dataType="float" value="0.990715890043" ucd="stat.probability"> <Description>Probability that the source is a binary neutron star merger (both objects lighter than 3 solar masses)</Description> </Param> <Param name="NSBH" dataType="float" value="0.0" ucd="stat.probability"> <Description>Probability that the source is a neutron star-black hole merger (primary heavier than 5 solar masses, secondary lighter than 3 solar masses)</Description> </Param> <Param name="BBH" dataType="float" value="0.0" ucd="stat.probability"> <Description>Probability that the source is a binary black hole merger (both objects heavier than 5 solar masses)</Description> </Param> <Param name="MassGap" dataType="float" value="0.0" ucd="stat.probability"> <Description>Probability that the source has at least one object between 3 and 5 solar masses</Description> </Param> <Param name="Terrestrial" dataType="float" value="0.00928410995716" ucd="stat.probability"> <Description>Probability that the source is terrestrial (i.e., a background noise fluctuation or a glitch)</Description> </Param> <Description>Source classification: binary neutron star (BNS), neutron star-black hole (NSBH), binary black hole (BBH), MassGap, or terrestrial (noise)</Description> </Group> <Group type="Properties"> <Param name="HasNS" dataType="float" value="1.0" ucd="stat.probability"> <Description>Probability that at least one object in the binary has a mass that is less than 2.83 solar masses</Description> </Param> <Param name="HasRemnant" dataType="float" value="1.0" ucd="stat.probability"> <Description>Probability that a nonzero mass was ejected outside the central remnant object</Description> </Param> <Description>Qualitative properties of the source, conditioned on the assumption that the signal is an astrophysical compact binary merger</Description> </Group> </What> <WhereWhen> <ObsDataLocation> <ObservatoryLocation id="LIGO Virgo"/> <ObservationLocation> <AstroCoordSystem id="UTC-FK5-GEO"/> <AstroCoords coord_system_id="UTC-FK5-GEO"> <Time> <TimeInstant> <ISOTime>2019-03-13T17:52:15.018661</ISOTime> </TimeInstant> </Time> </AstroCoords> </ObservationLocation> </ObsDataLocation> </WhereWhen> <How> <Description>Candidate gravitational wave event identified by low-latency analysis</Description> <Description>H1: LIGO Hanford 4 km gravitational wave detector</Description> <Description>L1: LIGO Livingston 4 km gravitational wave detector</Description> </How> <Citations> <EventIVORN cite="supersedes">ivo://gwnet/LVC#MS190313w-1-Preliminary</EventIVORN> <Description>Initial localization is now available</Description> </Citations> <Description>Report of a candidate gravitational wave event</Description> </voe:VOEvent>

//////////////////////// LVC Update voevent format /////////////////////////////////////

//////////////////////// LVC Retraction voevent format /////////////////////////////////
<?xml version="1.0" ?> <voe:VOEvent xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:voe="http://www.ivoa.net/xml/VOEvent/v2.0" xsi:schemaLocation="http://www.ivoa.net/xml/VOEvent/v2.0 http://www.ivoa.net/xml/VOEvent/VOEvent-v2.0.xsd" version="2.0" role="test" ivorn="ivo://gwnet/LVC#MS190313o-2-Retraction"> <Who> <Date>2019-03-13T12:39:00</Date> <Author> <contactName>LIGO Scientific Collaboration and Virgo Collaboration</contactName> </Author> </Who> <What> <Param name="Packet_Type" dataType="int" value="164"> <Description>The Notice Type number is assigned/used within GCN, eg type=164 is an LVC_RETRACTION notice</Description> </Param> <Param name="internal" dataType="int" value="0"> <Description>Indicates whether this event should be distributed to LSC/Virgo members only</Description> </Param> <Param name="Pkt_Ser_Num" dataType="string" value="2"> <Description>A number that increments by 1 each time a new revision is issued for this event</Description> </Param> <Param name="GraceID" dataType="string" value="MS190313o" ucd="meta.id"> <Description>Identifier in GraceDB</Description> </Param> <Param name="AlertType" dataType="string" value="Retraction" ucd="meta.version"> <Description>VOEvent alert type</Description> </Param> <Param name="HardwareInj" dataType="int" value="0" ucd="meta.number"> <Description>Indicates that this event is a hardware injection if 1, no if 0</Description> </Param> <Param name="OpenAlert" dataType="int" value="1" ucd="meta.number"> <Description>Indicates that this event is an open alert if 1, no if 0</Description> </Param> <Param name="EventPage" dataType="string" value="https://gracedb.ligo.org/superevents/MS190313o/view/" ucd="meta.ref.url"> <Description>Web page for evolving status of this GW candidate</Description> </Param> </What> <WhereWhen> <ObsDataLocation> <ObservatoryLocation id="LIGO Virgo"/> <ObservationLocation> <AstroCoordSystem id="UTC-FK5-GEO"/> <AstroCoords coord_system_id="UTC-FK5-GEO"> <Time> <TimeInstant> <ISOTime>2019-03-13T12:33:26.796455</ISOTime> </TimeInstant> </Time> </AstroCoords> </ObservationLocation> </ObsDataLocation> </WhereWhen> <Citations> <EventIVORN cite="retraction">ivo://gwnet/LVC#MS190313o-1-Preliminary</EventIVORN> <Description>Determined to not be a viable GW event candidate</Description> </Citations> </voe:VOEvent>
LVC Counterpart Notice Example

Here is an example of the LVC Counterpart Notice (e_mail format).

//////////////////////// COUNTERPART e-mail format (optical) ///////////////////////
TITLE:          GCN/LVC_COUNTERPART POSITION NOTICE
NOTICE_DATE:    Wed 07 Oct 14 10:34:46 UT
NOTICE_TYPE:    Optical
TRIGGER_NUM:    123456aa
CNTRPART_RA:    123.4560d {+08h 13m 49.4s} (J2000),
                123.4588d {+08h 13m 50.1s} (current),
                122.8101d {+08h 11m 14.4s} (1950)
CNTRPART_DEC:    +1.2344d {+01d 14' 03.8"} (J2000),
                 +1.2337d {+01d 14' 01.4"} (current),
                 +1.3866d {+01d 23' 11.6"} (1950)
CNTRPART_ERROR: 599.8 [arcsec, radius]
GRB_DATE:       14015 TJD;   280 DOY;   06/10/07
GRB_TIME:       36488.81 SOD {10:08:08.81} UT
OBS_DATE:       14015 TJD;   280 DOY;   06/10/07
OBS_TIME:       36518.00 SOD {10:08:38.00} UT
OBS_DUR:        10.0 [sec]
MAG:            16.5 +/- 1.0
FILTER:         U
SEEING:         1.5 [arcsec]
TELESCOPE:      ROTSE
SUBMITOR:       Eli_Rykoff
SUN_POSTN:      202.82d {+13h 31m 16s}   -9.54d {-09d 32' 34"}
SUN_DIST:        79.72 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:     162.75d {+10h 51m 01s}   +8.81d {+08d 48' 28"}
MOON_DIST:       39.84 [deg]
MOON_ILLUM:     14 [%] 
GAL_COORDS:     221.51, 18.83 [deg] galactic lon,lat of the counterpart
ECL_COORDS:     125.46,-18.18 [deg] ecliptic lon,lat of the counterpart
COMMENTS:       LVC COUNTERPART Coordinates.
/////////////////////// COUNTERPART e-mail format (x-ray) //////////////////////////
TITLE:          GCN/LVC_COUNTERPART POSITION NOTICE
NOTICE_DATE:    Sat 19 Oct 14 15:13:35 UT
NOTICE_TYPE:    Other
TRIGGER_NUM:    20141
CNTRPART_RA:    296.1749d {+19h 44m 41.9s} (J2000),
                296.2818d {+19h 45m 07.6s} (current),
                295.6628d {+19h 42m 39.0s} (1950)
CNTRPART_DEC:   +27.2113d {+27d 12' 40.6"} (J2000),
                +27.2370d {+27d 14' 13.1"} (current),
                +27.0896d {+27d 05' 22.5"} (1950)
CNTRPART_ERROR: 2.5 [arcsec, radius]
GRB_DATE:       15357 TJD;   -935 DOY;   13/01/-935
GRB_TIME:       0.00 SOD {00:00:00.00} UT
OBS_DATE:       15357 TJD;   -935 DOY;   13/01/-935
OBS_TIME:       58744.0 SOD {16:19:04.00} UT
OBS_DUR:        1950.0 [sec]
INTENSITY:      0.00e+00 +/- 0.00e+00 [erg/cm2/sec]
ENERGY:         0.3-10 [keV]
TELESCOPE:      Swift-XRT
SUBMITTER:      Phil_Evans
SUN_POSTN:      204.48d {+13h 37m 56s}  -10.18d {-10d 11' 05"}
SUN_DIST:        96.22 [deg]   Sun_angle= -6.1 [hr] (East of Sun)
MOON_POSTN:      31.79d {+02h 07m 10s}  +13.12d {+13d 06' 56"}
MOON_DIST:       88.81 [deg]
MOON_ILLUM:     100 [%]
GAL_COORDS:      62.97,  1.50 [deg] galactic lon,lat of the counterpart
ECL_COORDS:     305.48, 47.48 [deg] ecliptic lon,lat of the counterpart
COMMENTS:       LVC COUNTERPART Coordinates.  
COMMENTS:       Swift is performing multiple tiled observations of this LVC trigger.
COMMENTS:       This object is uncatalogued.   
COMMENTS:       The INTENSITY is the OBSERVED flux.
COMMENTS:       See http://www.swift.ac.uk/xrt_products/TILED_TBD00003 for more details.
COMMENTS:       We cannot confirm whether this is the GRB, or serendipitous.
//////////////////////// Counterpart cell/pager format /////////////////////////////
GCN/COUNTERPART
Optical
RA=218.27d  DEC=+59.36d
ERR=0.5deg
TIME: 23:05:12.83 UT
MAG=16.5 +/- 1.0
FILTER=U
SEEING=1.5 [arcsec]
//////////////////////// Counterpart short cell/pager format ///////////////////////
GRB_COUNTERPART
Optical
RA=295.663 DEC=+27.089
//////////////////////// Counterpart Subject-only format ///////////////////////////
GRB_COUNTERPART Optical RA=+19h 42m 39.0s DEC=+27d 14' 13.1"
//////////////////////// Counterpart ?????? format /////////////////////////////////
[i need to fill in these examples!!!]
////////////////////////////////////////////////////////////////////////////////////


Return to GCN/TAN homepage.
This file was last modified on 23-Mar-19.