SWIFTMASTR - Swift Master Catalog

Overview

This table records high-level information for each Swift observation and provides access to the data archive. Each record is associated with a single observation that contains data from all instruments on board Swift. The BAT is the large field of view instrument and operates in the 10-300 keV energy band. The narrow field instruments, XRT and UVOT, operate in the X-ray and UV/optical regime, respectively.

An observation is defined as a collection of snapshots, where a snapshot is defined as the time spent observing the same position continuously. Because of observing constraints, the length of a snapshot can be shorter than a single orbit and it can be interrupted because the satellite will point in a different direction of the sky or because the time allocated to that observation ends.

The typical Swift observing strategy for a Gamma Ray Burst (GRB) and/or afterglow, consists of a serious of observations aimed at following the GRB and its afterglow evolution. This strategy is achieved with two different type of observations named Automatic Targets and Pre-Planned Targets. The Automatic Target is initiated on board soon after an event is triggered by the BAT. The Figure of Merit (FOM) algorithm, part of the observatory's autonomy, decides if it is worth requesting a slew maneuver to point the narrow field instruments (NFI) on Swift, XRT and UVOT, in the direction of the trigger. If the conditions to slew to the new position are satisfied, the Automatic Target observation takes place; all the instruments have a pre-set standard configuration of operating modes and filters and about 20000 seconds on source will be collected. The Pre-Planned Target observations instead are initiated from the ground once the trigger is known. These observations are planned on ground and uploaded onto the spacecraft.

Bulletin

The SWIFTMASTR database table was last updated on 18 December 2024.

Provenance

This database table is generated at the Swift processing site. During operation, it is updated on daily basis.

Parameters

Name
This is the name of the pointed target. For GRBs, the name is assigned following the convention "GRBYYMMDD" or "GRBYYMMDDn" if multiple bursts occur within a day, where n is a letter.

Orig_Target_ID
This is a numerical value assigned automatically to each target and corresponds to the trigger number. In a few cases the same target_id may be assigned to different sky positions. Any target_id degeneracy is removed on the ground (see target_id parameter). The numerical value follows the convention adopted for Swift to assign the target identification. The numerical values can include up to 8 digits.

Target_ID
This is a unique numerical value assigned to each target and corresponds to the trigger number. This value is first assigned on board, but to remove the degeneracy in the assignment of target_id for the safe pointing position and/or to correct any wrong assignment of the target_id, the unique (or the correct) number is re-assigned on ground and stored in the target_id parameter. In these cases orig_target_id and target_id do not contain the same values; otherwise, they are identical. The numerical value follows the convention adopted for Swift to assign the target identification. The numerical values can include up to 8 digits.

RA
Right Ascension of the pointing position. Note that the pointing position can be different from the GRB (or other target) position.

Dec
Declination of the pointing position. Note that the pointing position can be different from the GRB (or other target) position.

Roll_Angle
Roll angle of the observation given in degrees.

Start_Time
Start time of the observation. Note that the date associated with the observation always contains the incoming slew.

Stop_Time
Stop time of the observation. For an Automatic Target, the stop time typically is after the satellite spends 20000 seconds exposure on source.

Orig_Obs_Segment
The Swift observation strategy is similar to a monitoring campaign, where a target is observed several times. The observation segment, recorded in this parameter, corresponds to the number of times a specific target has been observed. The numerical value follows the convention adopted for Swift to assign the observation segments and can include up to 3 digits. The first value for the segment is zero and is set on-board for the Automatic Target observation.

Obs_Segment
Observation Segment. The Swift observation strategy is similar to a monitoring campaign, where a target is observed several times. This parameter corresponds to the number of times a specific target has been observed and contains a value which has been corrected for any erroneous assignment. This re-assignment is done on the ground after the observation has been performed. If this was necessary the orig_obs_segment and obs_segment do not contain the same values; otherwise, they are identical. The numerical value follows the convention adopted for Swift for assigning the observation segments and can include up to 3 digits. The initial value for the segment is zero and is set on-board for the Automatic Target observation.

Orig_ObsID
This parameter contains a numeric value that should uniquely identify an observation. This value is the combination of the numerical value assigned to a target and the observation segment and is derived from the parameters orig_target_id and orig_obs_segment. Since these can be assigned incorrectly or may not be unique, the orig_obsid can also be wrong or not unique. The numerical value is a fixed 11-digit number, where the first 8 are for the target and last 3 are for the observation segment.

ObsID
This parameter contains a numeric value that uniquely identifies an observation. This value is the combination of the numerical value assigned to a target and the observation segment and is derived from the parameters target_id and obs_segment. The numerical value is a fixed 11-digit number, where the first 8 are for the target and last 3 are for the observation segment.

XRT_Exposure
The XRT exposure in seconds on source. The XRT collect science data in 5 different modes: Low-Rate Photodiode (LR), Piled-Up Photodiode (PU), Windowed Timing (WT), Photon Counting (PC) and Imaging (IM). These modes cannot be run simultaneously. The xrt_exposure is calculated as the sum of the exposures on source of all the science XRT modes used within this observation. If none of the science modes are used, this field is set to zero.

UVOT_Exposure
The UVOT exposure in seconds on source. The UVOT operates with 10 different filters (U, V, B, UVW1, UVW2, UVM2, White, Vgrism, Ugrism and Magnifier) in three different science modes (EVENT, IMAGE and EVENTIMAGE). The modes always use a filter and they can not be run simultaneously. The uvot_exposure is calculated as the sum of the exposures on source of all filters used within one observation regardless of the mode. If none of the science modes are used, this field is set to zero.

BAT_Exposure
The BAT exposure in seconds on source. The BAT can run simultaneously several modes. The main modes are the EVENT and SURVEY modes and they are alternated within an observation (never run simultaneously). Within an observation the EVENT mode is used when detecting a burst, otherwise the BAT collect data in the SURVEY mode. The bat_exposure on source is calculated as the sum of the effective exposure on source of the EVENT and SURVEY modes.

XRT_Expo_LR
The XRT exposure on source when the Low-Rate Photodiode (LR) mode was in use. If there are no data taken with the LR mode, this field is set to zero.

XRT_Expo_Pu
The XRT exposure on source when the Piled-Up Photodiode (PU) mode was in use. If there are no data taken with the PU mode, this field is set to zero.

XRT_Expo_Wt
The XRT exposure on source when the Windowed Timing (WT) mode was in use. If there are no data taken with the WT mode, this field is set to zero.

XRT_Expo_Pc
The XRT exposure on source when the Photon Counting (PC) mode was in use. If there are no data taken with the PC mode, this field is set to zero.

XRT_Expo_Im
The XRT exposure on source when the IMAGE (IM) mode was in use. If there are no data taken with the IM mode, this field is set to zero.

UVOT_Expo_Uu
The UVOT exposure on source when the U filter was in use. If there are no data taken with the U filter, this field is set to zero.

UVOT_Expo_BB
The UVOT exposure on source when the B filter was in use. If there are no data taken with the B filter, this field is set to zero.

UVOT_Expo_Vv
The UVOT exposure on source when the V filter was in use. If there are no data taken with the V filter, this field is set to zero.

UVOT_Expo_W1
The UVOT exposure on source when the UVW1 filter was in use. If there are no data taken with the UVW1 filter, this field is set to zero.

UVOT_Expo_W2
The UVOT exposure on source when the UVW2 filter was in use. If there are no data taken with the UVW1 filter, this field is set to zero.

UVOT_Expo_M2
The UVOT exposure on source when the UVM2 filter was in use. If there are no data taken with the UVM2 filter, this field is set to zero.

UVOT_Expo_Wh
The UVOT exposure on source when the White filter was in use. If there are no data taken with the White filter, this field is set to zero.

UVOT_Expo_Gu
The UVOT exposure on source when the UGRISM filter was in use. If there are no data taken with the UGRISM filter, this field is set to zero.

UVOT_Expo_Gv
The UVOT exposure on source when the VGRISM filter was in use. If there are no data taken with the VGRISM filter, this field is set to zero.

UVOT_Expo_Mg
The UVOT exposure on source when the Magnifier filter was in use. If there are no data taken with the Magnifier filter, this field is set to zero.

UVOT_Expo_Bl
The UVOT exposure on source when the blocking filter was in use. If there are no data taken with the blocking filter, this field is set to zero.

BAT_Expo_Ev
The BAT exposure on source when the EVENT mode was in use. Typically, this mode is used when a new trigger is detected. If there are no data taken with the EVENT mode, this field is set to zero.

BAT_Expo_Sv
BAT exposure on source when the SURVEY mode was in use. Typically this mode is always running during a Pre-Planned target observation or used after the EVENT mode for an Automatic Target observation. If there are no data taken with the SURVEY mode, this field is set to zero.

BAT_Expo_Rt
BAT exposure on source when the RATE mode was in use. If there are no data taken with the RATE mode, this field is set to zero.

BAT_Expo_Mt
Cumulative BAT exposure of all sources tagged with the MASKTAG mode. The MASKTAG mode is used to obtain rates in different energy band for a specific source. Within an observation rates for several sources can be tagged simultaneously using this mode. This field records the total exposure for all sources taken with the MASKTAG mode. The bat_no_masktag parameter records the number of sources for which there are MASKTAG mode data. On average the exposure per single source is obtained by dividing the cumulative MASKTAG exposure,bat_expo_mt, by the number of sources, bat_no_masktag. Typically one of the sources tagged with this mode within an observation corresponds to the GRB position.

BAT_Expo_Pl
BAT exposure on source when the PULSAR mode was in use. If there are no data taken with the PULSAR mode, this field is set to zero.

BAT_No_Masktag
Number of sources for which the MASKTAG rate mode is used within this observation.

Archive_Date
The archive_date is the date when the data are (expected) to arrive in the 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 within a week.

Software_Version
This records the version of the HEAsoft and Swift software used to process the observation data.

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.

Prnb
The proposal number of the observation. This field contains a value other than 0 or 1 only when the observation was requested via the GO program.

PI
Principal Investigator. If the Swift Announcement of Opportunity for proposals allows an observer to request a pointing, this field contains the name of the proposer. It is set to Swift for all other observations.

Att_Flag
The UVOT data provides a different attitude solution by matching the observed position with known catalogued stars. When that is possible, this flag is set to Y and indicates that an attitude reconstructed using the UVOT data is available. This however does not mean that it applies to all data. Currently, this attitude is not available and the flag is empty.

TDRSS_Flag
This flag is set to Y if TDRSS messages containing the first science information on the burst were sent to the ground during the observation.

GRB_Flag
This flag is set to Y if the observation contains data from a gamma-ray burst.

LII
Galactic Longitude of the pointing position. Note that the pointing position can be different from the GRB (or other target) position.

BII
Galactic Latitude of the pointing position. Note that the pointing position can be different from the GRB (or other target) position.

SAA_Fraction
This parameter reports the fraction of observing time spent in the SAA (South Atlantic Anomaly). This value is derived from the Swift timeline and is calculated as the ratio of the time flagged as in the SAA with the total observing time for each sequence. The values range from 0-1, where 0 indicates that no time was spent in the SAA during the observation.

AF_Total
This parameter reports the total time allocated for this sequence. It is derived from the Swift as-flown timeline. The value is given in seconds and includes the time spent on source and during the slews.

AF_OnSource
This parameter reports the total time spent on source for this sequence. It is derived from the Swift as-flown timeline. The value is given in seconds and may be different from the total exposure on source reported by each instrument.

AF_InSlew
This parameter reports the total time spent in slews for this sequence. It is derived from the Swift as-flown timeline. The value is given in seconds.

AF_InSAA
This parameter reports the total time spent in the SAA during the observation. It is derived from the Swift as-flown timeline. The value is given in seconds and includes the time spent in the SAA, whether it occurs on source or during slews.

Cycle
The proposal cycle number of the observation. Starting with cycle 3, observers can request pointings (initially only TOO). If the observation was not requested via the GO program, the value of this parameter is set to 1.

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:35:33 EDT