1. Introduction
  2. Notice types, Content, and Purpose
  3. Sequence of Activities
  4. Formats
  5. Filtering
  6. Error Boxes
  7. Test Notices
  8. Recognition
  9. Submission Process
  10. Further Help
  11. E-mail Examples
  12. Pager Examples
  13. Short-form Pager Examples
  14. Subject-only Pager Examples


The GCN system has been modified to incorporate the distribution
of positions of GRB Counterparts detected by the other instruments and telescopes.
These are locations of GRB counterparts detected by follow-up observers.

Like all the other sources of GRB information within the GCN system,
users can elect to receive (or not) these COUNTERPART Notices.

The GCN/COUNTERPART Notices are archived within the GCN website
in the Table of COUNTERPART Notices.

Notice Type, Content, and Purpose

Originally, there was only one notice type for COUNTERPART.
But as of March 2014, a variation has been added to deal with counterparts
detected during the Propriatory phase of the startup of the LIGO-Virgo (LVC) operations (i.e. LVC_COUNTERPART).
The have exactly the same content and format; only the distribution lists are different.

They are issued only when a follow-up observer detects a real or supsected counterpart AND submits a notice
via the web page form.
They contain the reported RA,Dec location of the burst counterpart candidate,
the date and time of the event, and several fields relating to the event:

The RA and Dec coordinates of the counterpart.

The Cntrpart_error is the radius of the circle that will contain on average 68% of the events.

The Intensity a measure of the intensity or flux of the counterpart (mag for optical, flux for radio and other).

The Inten_error field contains the uncertainty (sometimes statistical only; sometimes statistical plus systematic; it is follow-up instrument dependant).

The Seeing field contains the seeing during the observation. The units are arcsec.
Only really applicable to optical follow-up detections.

The Obs_tjd is the Truncated Julian Day of the start of the follow-up observation.
The Obs_sod is the Seconds-of-Day of the start of the observation.
The Obs_dur is the duration in seconds of the observation.

The ID_conf is the confidence level of the identification of the counterpart to the GRB/Transient.

The Tele_name gives the name of the telescope that made the follow-up observation and counterpart detection.

The Submittor is the name of the person that made the follow-up observation and counterpart detection.

Sequence of Activities

The sequence of activities for a typical burst follows:
1) A transient happens and is deteced by some GRB-/Transient-detecting space-based instrument.
2) The location of this burst is distributed to the world community by GCN.
3) Some person/group/instrument makes a follow-up observation of the burst error box.
4) They identify a counterpart to that burst.
5) They submit that counterpart location to GCN.
6) The Counterpart Notice is distributed to those GCN customers that have signed up to receive this notice type.


Samples of the E-mail, Pager, Short-form Pager, and Subject-only
distribution methods of the GCN/COUNTERPART 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.
The COUNTERPART Notice is type=45.
The LVC_COUNTERPART Notice is type=154.


Sites can elect to receive the COUNTERPART Notice type.
See filtering to see which filter functions are applicable.
This filtering applies to all the existing distribution
methods/media (sockets, email, pagers, cell).

Error Boxes

The uncertainty in the location will depend on:
(a) the counterpart_intensity,
(b) the waveband the follow-up observation is being made,
(c) the positional accuracy of the intrument/telescope making the follow-up observation,
(d) the seeing (if this is an optical follow-up, which will be most of them).

Test Notices

There is no test_notice version of this COUNTERPART type.
There are several other mission-based test notices within GCN, and
maybe they can fullfill your test notice needs.


Sites are encouraged to acknowledge the site/person and GCN in their publications
that contributed the counterpart notice that your follow-up observations were based on.

Submission Process

To submit a Counterpart Notice, you must be in the Circulars list -- this is how the vetting is done.
(For the Private-phase LVC_COUNTERPART, you must be in the LVC Circulars list.)

There are two ways to submit a COUNTERPART:
1) Webform: Fill in the 15 required fields and hit submit.
It will generate the proper format to be ingested into GCN.
and them email it to you, so that you can mail it to GCN. (This 2-step mailing procedure
is required because the only simple way to determine who is submitting is to check the identity
that the sendmail demon attaches to each email.)
2) Email: The body of an email is generated by the submitor and sent to GCN.
The Subject-line in the header of the email must be "GRB COUNTERPART SUBMISSION"
and the address is "vxw@capella2.gsfcnasa.gov".
This is best (most reliably) done by the submitor's data processing producing the email
with all the reguired "TOKEN: value" lines in the body of the email.

Further Help

For further information on this, please contact
Scott Barthelmy (for GCN issues),
these GCN web pages, and

E-mail Examples

Examples of the COUNTERPART 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 GRBs.
While based on trial data from the follow-up instrument,
the values 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 notice type:

//////////////// COUNTERPART e-mail format (optical) ///////////////////////
NOTICE_DATE:    Wed 07 Oct 06 10:34:46 UT
NOTICE_TYPE:    Optical
TRIGGER_NUM:    123456
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]
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
/////////////// COUNTERPART e-mail format (x-ray) //////////////////////////
NOTICE_DATE:    Sat 19 Oct 13 15:13:35 UT
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]
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:       GRB COUNTERPART Coordinates.  
COMMENTS:       Swift is performing multiple tiled observations of this GRB.  
COMMENTS:       This object is uncatalogued.  
COMMENTS:       The INTENSITY is the OBSERVED flux.  
COMMENTS:       See http://www.swift.ac.uk/xrt_products/TILED_GRB00003 for more details.  
COMMENTS:       We cannot confirm whether this is the GRB, or serendipitous.  

Pager Examples

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.

//////////////////////COUNTERPART Pager format//////////////////////////////
RA=218.27d  DEC=+59.36d
TIME: 23:05:12.83 UT
MAG=16.5 +/- 1.0
SEEING=1.5 [arcsec]

Short-form 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. The location is in B1950 epoch.

/////////////////////COUNTERPART Short-Pager format/////////////////////////
RA=295.663 DEC=+27.089

Subject-only Examples

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:

/////////////////////COUNTERPART Subject-only format/////////////////////////
[fill this in]
GRB_COUNTERPART Optical RA=+19h 42m 39.0s DEC=+27d 14' 13.1"

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This file was last modified on 30-May-15.