GCN/CALET GRB and Transient Light Curves

TABLE OF CONTENTS:

  1. Introduction
  2. Notice types, Content, and Purpose
  3. Occurance Rate
  4. Time_delays
  5. Formats
  6. Filtering
  7. Error Boxes
  8. Test Notices
  9. Recognition
  10. Further Help
  11. Archiving
  12. Misc
  13. E-mail Examples
  14. Cell/Pager Examples
  15. Short-form Cell/Pager Examples
  16. Subject-only Cell/Pager Examples

Introduction

The GCN system has been modified to incorporate the distribution
of lightcurves of GRBs, other unknown transients, and non-astrophysically-caused triggers
detected by the GBM instrument on the CALET spacecraft.

The CALET-GBM instrument will trigger about 10 times per month.

There are two type of Notices: CALT_GBM_FLT_LC and CALET_GBM_GND_LC;
covering these triggers detected in flight on-board (ie FLT) and after ground processing (ie GND).
They are sent to GCN and automatically distributed to those "sites"
that have the CALET Lightcurve notice types enabled
and that meet their filtering requirements.
The typical time delays a few minutes for the FLT Notice and a few hours for the GND notices.
These notices contain the trigger date/time and the lightcurve.
The GBM detectors are omni-directional -- no positional information available.

All the GCN/CALET_GBM_FLT_LC and GCN/CALET_GND_LC Notices are archived
within the GCN website in the Table of CALET-GBM Lightcurves.

Notice Types, Content, and Purpose

The CALET_GBM_FLT_LC Notice contains countrate lightcurve increases
that exceed a threshold value (over a time interval).
These increases can be caused by GRBs, other x-ray/hard_x-ray transients, and sometimes noise.
The Notices contain the date, time, and trigger criteria (timescale and energy_band).
This notice type does NOT contain any position information.
The GBM_GND_LC notice will almost always accompany the GBM_FLT_LC notice.

Occurance Rate

CALET-GBM will trigger about 10 times per month.
About 50% of the triggers will be of non-astrophysical origin.

Time_delays

The CALET automated ground software finds the transients and sends the message to GCN.
The time delays range from 1 to a few minutes for the FLT notice type and
a few hours for the GND notice type.

Formats

Samples of the E-mail, Cell/Pager, Short-form Cell/Pager, and Subject-only
distribution methods of the GCN/CALET_LC Notice type are included below.
(Also available in XML format via email, sockets, and VOEvent servers.)

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 appear 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.)

NUM   TYPE       SOCKET    FullFmt_EMAIL    PAGER/CELL      XML     VOEvent
                              w/Txt       (all 4 variants)          server
===   =======    ======    =============  ================  ===     =======
160   FLT_LC        P          B               B             B        Y
161   GND_LC        P          B               B             B        Y

where:
P = Packet (the GCN-standard 40 longword socket packet format)
B = Body of email (the GCN-standard "TOKEN: value" format)
A = The lightcurve plot is not available in the usual formats (GIF, JPEG, PS, PDF, and Text),
because the data is not available at the time of the Notice generation.
Y = Yes, it is available in this format.

Filtering

Sites can elect to receive the CALET_GBM_LC Notice types on a Notice-by-Notice basis.
Only the Notice_Type, Significance, and Delay filters are applicable to both CALET_GBM_LC notices.
See filtering to see which filter functions are applicable.
This filtering applies to all the existing distribution methods/media.

Error Boxes

Unlike many of the other GCN Notice types, there is no position information for the CALET_GBM Lightuve types.
The GBM instrument is omni-directional and cannot produce any directional information about the trigger.

Test Notices

There is no "test" type for the CALET_GBM Lightcurve Notice types.

Recognition

Sites are encouraged to acknowledge CALET-GBM and GCN in their publications
based on any observations or analyses using these GCN/CALET_GBM Lightcurve timestamps or lightcurves.

Further Help

For further information on this, please contact
Scott Barthelmy (for GCN issues),
or see the
CALET-GBM (Japan, in Japanese),
CALET (US site),
CALET (another US site),

Archiving

All past notices and lightcurves are archived at: GCN/CALET_GBM Lightcurve table.

Misc

A) Field Descriptions:

The "trig_num" is a uniquely identifying number for each trigger.
It is the on-board MET clock value at the time of the trigger.

The "trig_tjd" is the Truncated Julian Day of the CALET-GBM trigger,
eg. TJD=17023 is 01 Jan 2015.

The "trig_sod" is the UT seconds-of-day (SOD) of the CALET-GBM trigger.
The units are second to two decimal places.

The "point_ra" and "point_dec" fields specify the RA,Dec pointing direction
of the boresight of the spacecraft (in J2000 epoch).

The "lc_signif" signal-to-noise ratio (units of sigma) during the foreground interval
over the background interval(s).

The "fore_dur" the amount of time (in units sec) the defines the triggering interval.
There are only 4 foreground/triggering intervals 0.25s, 0.5s, 1s and 4s defined
in the on-board triggering logic.

The "bkg_dur1" is the amount of time (units sec) used to determine the background countrate
when used for the lc_significance. For the (on-board) Flight triggers, there is only
one background interval used, and it occurs before the foreground interval
(with a separation of X.X sec between the end of the background interval and
the beginning of the foreground interval).

The "bkg_dur2" is the amount of time (units sec) used to determine the background countrate
when used for the lc_significance. It is used only for the Ground-porcessed triggers.
It comes after the fore_dur interval. The separation between the end of the fore_dur
and the beginning of the bkg_dur2 interval is X.X sec.

The "lon_lat" is the Longitude and Latitude of the CALET s/c at the time of the CALET-GBM trigger.

The "trig_id" field contains (a) flag bits on the type of solution
that was found by the CALET pipeline processing and
(b) flag bits that are assigned in the GCN ground-processing.

The "trig_id" field contains (a) flag bits on the type of solution
that was found by the CALET pipeline processing and
(b) flag bits that are assigned in the GCN ground-processing.
The bit packing of the "trig_id" entry in the packet is:
BitNum  F-v-G  Item_name      Description
------  ----   ---------      -----------
0-4      -     spare          spare for future use
5        G     retraction     0=No or 1=Yes, it is definitely not real, a Retraction
6-28     -     spare          spare for future use
29       G     temporal_coinc 0=No or 1=Yes, there was a temporal coincidence with another event
30             test_submit    0=No or 1=Yes, this is a test submission (internal use only)
31       -     spare          spare for future use
The columns are:  "BitNum" is the 2^N location within the 4-byte word;
"Item_name" is the short-description name of the quantity;  and
"Description" is the longer description of the quantity.

The "misc" field contains various bit_flags.

The "misc" field contains various bit_flags.
The bit packing is:
Bit_Number     Item_name      Description
----------     ---------      -----------
0              HMX1_det       HMX1 detector participated in the trigger
1              HMX2_det       HMX2 detector participated in the trigger
2              SGM_det        SGM detector participated in the trigger
3-7            spare          spare
8-14           e_band         E_band_index (which e_band was this trigger)
2^15-31        spare          Spare bits within 'misc'.

Index    E-band range
-----    -------------
0        "undef" keV
1        "7- 10" keV
2        "7- 25" keV
3        "7- 50" keV
4        "7-100" keV
5       "10- 25" keV
6       "10- 50" keV
7       "10-100" keV
8       "25- 50" keV
9       "25-100" keV
10      "50-100" keV
11      "40-100" keV
12      "40-230" keV
13      "40-450" keV
14      "40-1000" keV
15     "100-230" keV
16     "100-450" keV
17     "100-1000" keV
18     "230-450" keV
19     "230-1000" keV
20     "450-1000" keV

The URL for retrieving the lightcurve can be generated by appending
the string stored at starting location url_c0_3 onto:
http://cgbm.calet.jp/cgbm_trigger/flight/
and
http://cgbm.calet.jp/cgbm_trigger/ground/
You can then use wget or curl (or similar) to retrieve
the lightcurve file from the CALET science data center.


B) Pushed-vs-Pulled Lightcurve Data:

The actual lighcurve data is not part of the Notice that is distributed -- it is not 'pushed' to you.
Only a URL pointing to the lightcurve datafile is distributed.
You must then use 'wget' or 'curl' (or similar) to 'pull' the data file from the hostsite machnine.


C) Other Lightcurve Data Streams within GCN:

Here are the other missions/instruments within GCN that produce lightcurves:
KONUS:                     Description page   Archive_page,
INTEGRAL-SPIACS: Description page   Archive_page,
Suzaku:                      Description page   Archive_page,
Swift-BAT:                 Description page   Archive_page,
Fermi-GBM:               Description page   Archive_page.


E-mail Example

Examples of the CALET_GBM Lightcurve 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 events.
While based on flght 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/CALET_GBM_FLT_LIGHTCURVE
GCN/CALET_GBM_GND_LIGHTCURVE

/////////////////////////GBM FLT LC e-mail format//////////////////////////////
TITLE:           GCN/CALET NOTICE
NOTICE_DATE:     Fri 11 Mar 16 23:32:25 UT
NOTICE_TYPE:     CALET GBM Flight Lightcurve
POINT_RA:        123.46d {+08h 13m 50s} (J2000),
POINT_DEC:       -54.32d {-54d 19' 14"} (J2000),
TRIGGER_NUM:     123456789
TRIGGER_DATE:    17457 TJD;    70 DOY;   16/03/11
TRIGGER_TIME:    84737.00 SOD {23:32:17.00} UT
TRIGGER_DET:     1 1 0 (HXM1 HXM2 SGM)
SIGNIFICANCE:    12.34 [sigma]
FOREGND_DUR:     4.00 [sec]
BACKGND_DUR1:    2.00 [sec]
ENERGY_BAND:     18-52 [keV]
SC_LON_LAT:       0.52, 0.18 [deg]
LC_URL:          http://cgbm.calet.jp/cgbm_trigger/flight//123456789/index.html
COMMENTS:        CALET-GBM Flight Lightcurve.
/////////////////////////GBM GND LC e-mail format//////////////////////////////
TITLE:           GCN/CALET NOTICE
NOTICE_DATE:     Fri 11 Mar 16 23:32:25 UT
NOTICE_TYPE:     CALET GBM Ground Lightcurve
POINT_RA:        123.46d {+08h 13m 50s} (J2000),
POINT_DEC:       -54.32d {-54d 19' 14"} (J2000),
TRIGGER_NUM:     123456789
TRIGGER_DATE:    17457 TJD;    70 DOY;   16/03/11
TRIGGER_TIME:    84737.00 SOD {23:32:17.00} UT
TRIGGER_DET:     1 1 0 (HXM1 HXM2 SGM)
SIGNIFICANCE:    12.34 [sigma]
FOREGND_DUR:     4.00 [sec]
BACKGND_DUR1:    2.00 [sec]
BACKGND_DUR2:    1.00 [sec]
ENERGY_BAND:     18-52 [keV]
SC_LON_LAT:       0.52, 0.18 [deg]
LC_URL:          http://cgbm.calet.jp/cgbm_trigger/ground/123456789/index.html
COMMENTS:        CALET-GBM Ground Lightcurve.
///////////////////////////////////////////////////////////////////////////////

Cell/Pager Example

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.

/////////////////////////GBM FLT LC Cell/Pager format//////////////////////////
GCN/CALET-GBM
Flight Lightcurve
T=01:24:49.75 UT
SIGNIF=10.30 [sigma]
/////////////////////////GBM GND LC Cell/Pager format//////////////////////////
GCN/CALET-GBM
Ground Lightcurve RETRACTION
T=01:24:49.75 UT
SIGNIF=12.34 [sigma]
///////////////////////////////////////////////////////////////////////////////

Short-form Cell/Pager Example

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.

/////////////////////////GBM FLT LC Short-Cell/Pager format////////////////////
CALET_GBM_FLT_LC
DATE: 16/03/03
T=01:24:49.75
/////////////////////////GBM GND LC Short-Cell/Pager format////////////////////
CALET_GBM_GND_LC
DATE: 16/03/03
T=01:24:49.75
///////////////////////////////////////////////////////////////////////////////


Subject-only Example

/////////////////////////GBM FLT LC Subject-only format////////////////////////
CALET_GBM_FLT_LC T=01:24:49.75 UT
/////////////////////////GBM GND LC Subject-only format////////////////////////
CALET_GBM_GND_LC T=01:24:49.75 UT
///////////////////////////////////////////////////////////////////////////////


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This file was last modified on 11-Mar-16.