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SUZAKUWAM - Suzaku Wide-Band All-Sky Monitor (WAM) Catalog of Event Lightcurves

 HEASARC
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Overview

This database table contains information of the events detected by the Wide-band All-sky Monitor (WAM) on Suzaku during its ~10 years of operation. Each event has associated data products. The lightcurves are derived from the on-board operating modes that collected the WAM data from each of the sub-detectors. The lightcurves are rates as a function of time in different energy bands, and they can be used with the general FITS tools within HEAsoft or XRONOS.

Catalog Bibcodes

2009PASJ...61S..35Y
2010PASJ...62.1341E

References

Design and In-orbit performance of the Suzaku Wide-band All-sky Monitor
    Yamaoka, K., et al., <Publ. Astron. Soc. Japan, Vol. 61, S35-S53 (2009)>
    =2009PASJ...61S..35Y

A Catalog of Suzaku/WAM Hard X-Ray Solar Flares
    Akira, E., et al., <Publ. Astron. Soc. Japan, Vol. 62, Issue 5, 1341-1349 (2010)>
    =2010PASJ...62.1341E

Provenance

Version 3 of the lightcurves were generated at HEASARC from the version 2 files, and they are now the final versions hosted at both HEASARC and DARTS. This database table reflects version 3 of the data products.

Version 2 of the FITS lightcurves and their plots were generated at Saitama University in Japan and a copy hosted at the DARTS archive, located at ISAS (http://www.darts.isas.ac.jp/pub/suzaku/wam-2.0/).

Description

The Wide-band All-sky Monitor (WAM) was a subsystem of the Hard X-ray Detector (HXD) on board Suzaku and consists of 20 bismuth germanium oxide (BGO) detectors surrounding the HXD on four sides. The primary role of the lateral BGO crystals (WAM walls) was to serve as active shields for the HXD main detectors. However, their large effective area, which reached per side 800 cm2 at 100 keV and remained 400 cm2 even at 1 MeV, and good time resolution made the WAM an ideal instrument for observing transient objects emitting hard X-rays, including solar flares, gamma-ray bursts (GRBs), and soft gamma-ray repeaters. It had an uncollimated field of view (FOV), since it was located at the side of the HXD, and a relatively unobstructed field of view thanks to the HXD position on the Suzaku satellite sitting on an extensible optical bench (EOB) to maintain its FOV.

The WAM walls were named WAM0, WAM1, WAM2, and WAM3. The WAM data were taken in two modes: 1) TRN mode, a binned mode always operating at all times, or 2) BST mode, which was activated when a trigger occurs. The following table reports the characteristics of the two modes: 

  Mode           Epoch             Energy    Time resolution     Time coverage

  BST   2005-08-22 2006-03-20        4ch        1/32s (TH)       128s (16s before and 112s after the trigger)
                                    55ch           1s (PH)
        2006-03-20 to mission end    4ch        1/64s (TH)        64s (8 s before and 56 s after the trigger)
                                    55ch         0.5s (PH)

  TRN   2005-08-22 to mission end   55ch           1s (PH)       Always transferred to the telemetry every 1 s

The WAM triggered a GRB or transient event on-board by using the rising edge of the count rate by 5.5 rms of the previous 8 s background count rate, and stores 4 energy-resolved light curves for the period between 8 s (16 s before 2006 March 20) before and 56 s (112 s) after the trigger.

The WAM data are stored in two different formats, "TH" and "PH". The TH data contain 4 energy-resolved light curves with high time resolution: either 1/64 s for a 64 s time interval (for data collected on March 20 2006 and later), or 1/32 s for 128 s time interval (prior to March 20 2006). The energy band of each TH light curve is labeled as TH0, TH1, TH2, or TH3, which nominally cover the 50-110 keV, 110-220 keV, 220-540 keV, and 540-5000 keV bands, respectively. PH data contains 54 energy bin spectra at 1-s time resolution covering the energy band between 50 keV and 5 MeV, which are continuously accumulated to provide background information for the HXD. The TH energy bands correspond to the following channels of the PH mode: TH0 is PH2-3, TH1 is PH 4-7, TH2 is PH8-16 and TH3 is PH 17-54.

Since the WAM had no imaging capabilities, the incidence angle is derived only for GRBs whose position were obtained from simultaneous observation results from the interplanetary network (IPN), Swift/BAT, and/or Fermi/GBM.

For each detected event, there are associated the telemetered TRN and BST mode data and the light curves derived from these modes. If the event was triggered on board light curves are calculated for both TRN and BST mode data. If the event was found in the ground analysis light curves are calculated instead only from TRN mode. There is a light curve for each WAM (0,1,2,3), and for each WAM, the light curves are in four energy channels (TH0, TH1, TH2, or TH3). For the BST mode, the energy dependent light curves are derived from the TH data. For the TRN mode, the energy dependent light curve are derived from the PH data binned to match the range of the TH data.

Parameters

Event_ID
This parameter contains a unique row identifier for the database table. It is based on the time of the event, and the 12 digits correspond to the date/time in YYMMDDHHMMSS format.

SuzakuID
This parameter contains the Suzaku observation or sequence identifier. Within this database table, this value is not unique because more than one event could be detected from the same Suzaku observation sequence. Events identified during the slew have this value set to 999999xxx since the slew data are not included in the public Suzaku archive.

Trigger_ID
This parameter contains the unique identifier for the event. Values range from 1-3000 for events that were triggered on-board and 4000-9000 for events which were not triggered on-board.

Time
This parameter contains the date and time of when the event occurred.

EvtType
This parameter contains a string that identified whether or not the event was triggered on board or discovered in the ground analysis. The possible values are 'trigger' (detected on board) or 'untrigger' (detected on ground analysis).

EvtClass
This parameter contains a string that classifies the event. The following are the possible values: 

     operation
     solarflare
     confirmedGRB
     possibleGRB
     possibleAXP/SGR
     confirmedAXP/SGR
     noise/spike
     particle/SAA
If the event is classified as 'operation', this is not a real event but caused by different operation-related issues, such as turning-on the high voltages and checking the WAM health condition using a special mode named WAMscan.

If the event is classified 'confirmedGRB' or 'confirmedAXP/SGR', the event was also seen by other satellites.

If the event is classified as 'possibleGRB' or 'possibleAXP/SGR' , the event was not confirmed by other satellites.

If the event is classified as 'noise/spike', the event had a rate increase of 1 sec in the 'Transient Mode' but no increase in the 'Burst Mode'.

If the event is classified as 'particle/SAA', the event was due to either high latitude event (Canada) probably due to electron trapped in the geomagnetic poles or an event associated with the South Atlantic Anomaly (SAA) passage. (Note that the WAM was turned off in the SAA, but the WAM could detect the initial onset of the SAA before being cycled off.)

Name
This parameter contains the name of a GRB or a celestial source only if the event has been identified. In all other cases is left empty.

WAM0
This parameter reports whether or not the event has been detected by the WAM0 (yes/no).

WAM1
This parameter reports whether or not the event has been detected by the WAM1 (yes/no).

WAM2
This parameter reports whether or not the event has been detected by the WAM2 (yes/no).

WAM3
This parameter reports whether or not the event has been detected by the WAM3 (yes/no).

Theta
This parameter contains the event incident theta angle. This angle is defined as the direction of the event with respect to the Z-axis of the satellite. This parameter is provided only for localized events with RA and Dec.

Phi
This parameter contains the event incident phi angle. This angle is defined as the direction of the event projected on the XY plane with respect to the X-axis of the satellite. This parameter is provided only for localized events with RA and Dec.

RA
The Right Ascension of the event or object. This is the position reported either by other satellites that detect the event or in the catalog for celestial sources. This is not derived from the WAM. This was given in units of degrees to a precision of 0.001 degrees in the original data.

Dec
The Declination of the event or object. This is the position reported either by other satellites that detect the event or in the catalog for celestial sources. This is not derived from the WAM. This was given in units of degrees to a precision of 0.001 degrees in the original data.

LII
The Galactic longitude of the event or object. This was calculated from the RA and Dec position.

BII
The Galactic latitude of the event or object. This was calculated from the RA and Dec position.

T90
This parameter contains the duration of the time interval during which 90% of the total observed counts have been detected. The start and stop of the T90 interval are defined by the time at which 5% and 95% of the total counts have been detected. This value, given in seconds, is derived for the energy band 50-5000 keV.

Fluence
This parameter contains the flux in the energy range 50-5000 keV, derived from the WAM spectra (using the best fit model), and turned into a fluence in erg cm-2 using the T100, the time interval during which 100% of the total observed counts have been detected. The parameter also reports the energy range if different from the default.

WAMRef
This parameter provides the reference to the GCN circular that reported the WAM results for the event.

Other
This parameter provides the list of the other satellites that have detected the event.

Redshift
This parameter provides the redshift of the event as reported on the website at http://www.mpe.mpg.de/~jcg/grbgen.html.

PosRef
This parameter provides the biblography reference from which the event position reported in the parameters 'ra' and 'dec' are derived.

GOESClass
If the event is classified as a solar flare, this parameter reports the classification of the solar flare as reported by the GOES satellite. The website http://spaceweather.com/glossary/flareclasses.html provides the explanation for each class.

Comment
This parameter reports additional information regarding the event.

Contact Person

Questions regarding the SUZAKUWAM database table can be addressed to the HEASARC Help Desk.
Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:35:23 EDT