SWIFTGUANO - Swift Gamma-ray Urgent Archiver for Novel Opportunities (GUANO) Events

Overview

The Swift Observatory provides event-level data from the Burst Alert Telescope (BAT) on demand in response to transients detected by other observatories/instruments. This capability, named "Gamma-ray Urgent Archiver for Novel Opportunities" (GUANO), was introduced in 2020. In normal operations, BAT records the arrival time (to 100-microsecond accuracy), location (in detector coordinates), and energy (in one of 80 bins from 15 to 350 keV) for each individual count that strikes the detector. These data, referred as event-by-event (or event), because of the large effective area of the BAT, produces a large data volume that cannot all be stored onboard or telemetered to the ground. For this reason, the BAT has relied on the performance of its onboard real-time detection algorithms, and only preserves event data and telemeters them to the ground around the time of events that trigger these onboard algorithms. The GUANO implementation allows to download BAT event data that did not trigger on board.

Upon receiving an alert from different observatories, an autonomous spacecraft-commanding pipeline requests to download from the Swift satellite the BAT event data around the time of the GUANO event with a time window, typically around 200 seconds. The satellite does not slew; therefore, only BAT event data are available for the GUANO event and these data are tagged with a sequence number associated with the ongoing observation containing the GUANO time window.

This table records the times of the GUANO events from different observatories from which Swift was able to download the BAT event data together with the directory and file names where the event are located in the archive. There is one record for each trigger by an external observatory that requested BAT event data; therefore, it is possible that multiple records are associated with the same event.

Catalog Bibcode

2020ApJ...900...35T

Bulletin

The SWIFTGUANO database table was last updated on 21 November 2024.

References

Gamma-Ray Urgent Archiver for Novel Opportunities (GUANO): Swift/BAT Event Data
    Dumps on Demand to Enable Sensitive Subthreshold GRB Searches,
    Tohuvavohu A., et al., Astrophysical Journal Volume 900, 30 (2020).
   =2020ApJ...900...35T

Provenance

This contents of this database table are generated at the Swift processing site. During operation, it is updated for any new GUANO trigger. These updates are then delivered to the HEASARC and ingested into the HEASARC database in a timely fashion. Note that some parameters (specifically, the galactic coordinates) have been added and are populated by the HEASARC.

Parameters

Unique_ID
This parameter contains the unique identification number for each record in this table.

Name
The designation of the GUANO event. The name is typically set by the observatory that initiated the alert.

ObsID
This parameter contains a numeric value that uniquely identifies a Swift observation. The GUANO BAT event data are within this ObsID.

RA
The Right Ascension of the Swift pointing for this ObsID. Note: Because of the BAT's large field of view, this position may be different from the GUANO position.

Dec
The Declination of the Swift pointing for this ObsID. Note: Because of the BAT's large field of view, this position may be different from the GUANO position.

LII
The Galactic Longitude of the Swift pointing for this ObsID. Note: Because of the BAT's large field of view, this position may be different from the GUANO position. This field has been added by the HEASARC and is calculated from the provided Equatorial position.

BII
The Galactic Latitude of the Swift pointing for this ObsID. Note: Because of the BAT's large field of view, this position may be different from the GUANO position. This field has been added by the HEASARC and is calculated from the provided Equatorial position.

Roll_Angle
The roll angle (in degrees) of the Swift observation for this ObsID.

Start_Time
The start time of the Swift observation for this ObsID.

Stop_Time
The stop time of the Swift observation for this ObsID.

Trigger_Time
This parameter records the time of the GUANO trigger as recorded by the external observatory. If the same GUANO event is reported by different observatories, there is one each record per observatory.

Trigger_Start_Time
The start time of the window associated to the trigger for which the BAT events data are requested.

Trigger_Stop_Time
The stop time of the window associated to the trigger for which the BAT events data are requested.

Trigger_Exposure
This parameter records the requested exposure (in seconds).

Directory
This contains the name of the top directory in the Swift data archive where the data are located. Possible values are either 'obs' or 'tdrss'.

Eventfile1
The first BAT event file name that contains the event data associated with the GUANO event.

Eventfile2
The second BAT event file name that contains the event data associated with the GUANO event. Depending on the Swift current operation the requested BAT event may be located in different files (up to two files).

Archive_Date
This is the date when the data are expected to arrive in the public Swift data archive. There is a delay of about one week between the time when the data arrive on ground and are processed and when the data are sent to the archive. Therefore, observations made by Swift within about a week of the present are listed in this table, but the actual data files will arrive in the archive later (within a week).

Processing_Date
This records the date when the data were processed. If a data set has been processed more than one time, it reports the date of the last processing.

Processing_Version
This records the version of the processing script used in the pipeline to generate the data products from the observation.

Num_Processed
This records the number of times a data set has been processed using the same processing version of the script.

Contact Person

Questions regarding the SWIFTGUANO database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:35:32 EDT