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GINGARAW: Help

GINGARAW - Ginga LAC Raw Data


Overview

The GINGARAW database table provides access to the raw GINGA files in FITS format for the LAC experiment.

Ginga was the third Japanese X-ray astronomy satellite. It was launched into low Earth orbit on 5th February 1987 and re-entered the atmosphere on 1st November 1991. The scientific payload consisted of the Large Area Counter (LAC; Turner et al. 1989), the All-Sky Monitor (ASM; Tsunemi et al. 1989) and the Gamma-ray Burst Detector (GBD; Murakami et al. 1989). A full description of the satellite is given in Makino et al. (1987). During its lifetime Ginga performed over 1000 pointed observations of approximately 350 different targets, covering all then known classes of cosmic X-ray sources.

The LAC experiment, sensitive to X-rays with energy 1.5-37 keV, was the main scientific instrument aboard Ginga. It was designed and built under a Japan-UK collaboration (ISAS, U. Tokyo, Nagoya U., U. Leicester, Rutherford Appleton Lab). It consisted of an array of eight collimated co-aligned proportional counters with a total effective area of approximately 4000 cm^2. Steel collimators restricted the field of view to 1.1 x 2.0 degrees (FWHM).


Provenance

This database table was last updated by the HEASARC in August 2005. Galactic coordinates were added and some parameters were renamed to adhere to the HEASARC's current parameter naming conventions.

Data Products

The only data product associated with the entries in this table is a FITS file containing the raw data recorded from Ginga observations.

Data received from Ginga were stored in First Reduction Files (FRFs) which mirror the telemetry stream from the satellite. Each FRF file corresponds to a period of time when the satellite was in contact with the ground. Some of the data were telemetered in real time and other data were telemetered from the bubble memory on board. Each FRF file can contain data up to 3 different pointing positions. The raw FITS Ginga data are the FRF files restored in FITS format from their native format (ADP grant, PI Corbet, at Penn State). The FITS files were processed from Penn State on a HEASARC machine and the files directly transferred to the Ginga FTP area at HEASARC. The FITS files are bintable with 5 extensions containing raw counts (science data), raw orbital data, raw operational status data, raw housekeeping data and good time intervals. The layout of the science data extension consists of several columns containing counts, stored as an array per row, and one containing time. The datamode sets the number of channels for the count arrays, how the signal from each counter is summed (number of columns) and the integration time.

This database table was derived using keywords stored in the primary header of the FITS file. Each record corresponds to a different pointing position; therefore, it is possible that up to 3 records may be associated with the same FITS file but have different object names and positions.


Parameters

Name
Source designation.

RA
Right Ascension of the source in the selected equinox.

Dec
Declination of the source in the selected equinox.

LII
Galactic Longitude of the source.

BII
Galactic Latitude of the source.

ObsID
This parameter is the observation ID. This was also known as the Sirius number.

Mode
This parameter stored the different data mode. The possible values are MPC1, MPC2 MPC3 and PC. The combination of mode and bit rate define the number of channels, integration time and the number of output signals from the LAC.

Hmlrate
This parameter stored the bit rate. The possible values are L (low), M (medium), and H (high).

Status
This parameter stored the observing mode. The possible value are POINTING or SCANNING.

Readouts
Number of read-outs included in the file.

Elapsed_Time
Gives the total observing time in seconds included in the file.

Ontime
Gives the total good time included in the file in days.

Start_DMY
Give the start time of the observation, stored as a string.

End_DMY
Give the stop time of the observation, stored as a string.

Start_Time
Give the start time of the observation, stored as a number.

End_Time
Give the stop time of the observation, stored as a number.

Read_Time
The readout time is the integration time for each row in the FITS file and is given in seconds.

Filename
The name of the file associated to this database record.


Contact Person

Questions regarding the GINGARAW database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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