SSSRAW - Einstein SSS and MPC Raw Data

Overview

The Einstein Observatory (also known as HEAO-2 or HEAO-B) was operational from 1978 November 13 until 1981 April 25 when the attitude control system failed. The Solid State Spectrometer (SSS) was operated intermittently between 1978 December 1 and 1979 October 22. However, the cryogen cooling for the detector was used up by about 2 weeks prior to the date of this last observation, so that the last reliable observation of the SSS is considered to have occurred on 1979 October 03. The SSSRAW database accesses the raw SSS data (and the associated monitoring proportional counter, MPC, data), restored in FITS format at HEASARC from the original machine dependent format data set.

Data Products

Each entry in this database has an associated FITS file containing the Einstein SSS raw data and the associated MPC data. The SSS instrument could be operated in any of 3 different data-gathering modes: PHA mode, DELTA-T mode, and MS mode. Within each mode different data-streams were obtained setting either different time resolution parameter and/or different number of energy channels. A typical Einstein SSS FITS raw data file contains ten extensions (eight dedicated to SSS data and two to the simultaneous MPC data set), all of them having the same FITS layout/structure. Within each SSS extension, stream of data, obtained within an observation, from the three different modes with 'similar' characteristics are combined together. Therefore the original datamode is not unique within an extension. The files always contain the 10 extensions but not all the extensions contain data. The SSSRAW database records for each entry the number of rows present in the file for each extension. This allows a search for a particular data type. Listed below is a brief description of the different data types contained in theeight SSS extensions and the parameters which identified the extensions within this database :

 * 128 channel spectra accumulated either with a time resolution of 2.56,
   1.28 or 0.64 seconds (3 extensions).
   Parameters : SSS_SPEC_2_56S, SSS_SPEC_1_28S and MS
 * Intensity data over the full energy range with a time resolution of
   2, 5 and 10 ms (3 extensions).
   Parameters : SSS_TWO_MS, SSS_FIVE_MS and SSS_TEN_MS.
 * PHA values  of the first 512 events recorded in 1.28 seconds
   (1 extension). Parameter : RT_PHA
 * Histogram of 128 bins from the DELTA mode (1 extension).
   Parameter : DELTA

The MPC extensions contain the following data types associated to the following database parameters:

 * 8 channel spectra accumulated every 2.56 sec (1 extension).
   parameter : MPC_SPEC_2_56S.
 * Intensity value of the first 512 events recorded in 1.28 seconds
    parameter : MPC_TIP.

Parameters

Time
The start date and time of the observation.

End_Time
The stop date and time of the observation.

RA
The right ascension of the observation. Note that for all files corresponding to a SLEW (as set in the Target parameter or in the OBJECT keyword in the fits file), the RA, DEC, LII, and BII have been set to -9999.

Dec
The declination of the observation. The right ascension of the observation. Note that for all files corresponding to a SLEW (as set in the Target parameter or in the OBJECT keyword in the fits file), the RA, DEC, LII, and BII have been set to -9999.

LII
The galactic longitude of the observation. The right ascension of the observation. Note that for all files corresponding to a SLEW (as set in the Target parameter or in the OBJECT keyword in the fits file), the RA, DEC, LII, and BII have been set to -9999.

BII
The galactic latitude of the observation. The right ascension of the observation. Note that for all files corresponding to a SLEW (as set in the Target parameter or in the OBJECT keyword in the fits file), the RA, DEC, LII, and BII have been set to -9999.

Observation_ID
Observation ID Sequence Number

Tape_Number
The number of the original IBM data tape.

File_Number
The file number of the observation, on the original IBM data tape.

Sssmode
This parameter contains a string describing the modes used to to create the SSS raw FITS file. The possible modes were PH, DT (for DELTA-T mode) and MS. The SSSMODE parameter can be a combination of one or all three modes.

Telapse
The total length in time of the observation interval, in seconds.

Exposure
The total good exposure of the observation interval, in seconds.

SSS_Spec_2_56s
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. The extension contains 128 channel spectrum every 2.56 seconds. The FITS extension layout is such that each row has one spectrum integrated 2.56 seconds.

SSS_Two_Ms
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. The extension contains intensity value every 2 ms over the full energy range. The FITS extension layout is such that each row contains 1024 bin integrated 2.5 ms.

SSS_Five_Ms
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. The extension contains intensity value every 5 ms over the full energy range.The FITS extension layout is such that each row contains 512 bin integrated 5 ms.

SSS_Ten_Ms
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. The extension contains intensity value every 10 ms over the full energy range.The FITS extension layout is such that each row contains 256 bin integrated 10 ms.

MPC_Spec_2_56s
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. The extension contains a 8 channel spectrum every 2.56 seconds. The FITS extension layout is such that each row has one spectrum integrated 2.56 seconds.

MPC_Tip
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. This extension contains time values for the 'first' 512 events detected every 1.28 seconds. The FITS extension layout is such that each row has an array of 512 time value.

SSS_Spec_1_28s
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. The extension contains 128 channel spectrum every 1.28 seconds. The FITS extension layout is such that each row has one spectrum integrated 1.28 seconds.

Rt_Pha
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. The extension contain PHA channel value for 'first' 512 events detected every 1.28 seconds. The FITS extension layout is such that each row has an array of 512 PHA channel value.

Delta_T
Number of Rows of Delta T (ext 9) Data

Ms
This parameter gives the number of rows present in the file for this extension. If the value is 0, the extension consists only in the header. The extension contains 128 channel spectrum every 0.64 seconds. The FITS extension layout is such that each row has one spectrum integrated 0.64 seconds.

Name
The name of the source.

File_Spectra
The name of the SSS raw file associated to this database entry.

Contact Person

Questions regarding the SSSRAW database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: Tuesday, 09-Nov-2004 18:26:12 EST