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IPCUNSCRND: Help

IPCUNSCRND - Einstein IPC Unscreened Photon Event List


Overview

This database table gives access to the IPC unscreened data set, which includes files in the event list format together with auxiliary files. This data set was generated by the Einstein Data Center and delivered to the HEASARC on CD-ROM.

The Einstein Observatory (HEAO-2) operated from November 1978 to April 1981. Einstein carried the first fully imaging X-ray telescope in space and operated in pointing mode. The Imaging Proportional Counter had a bandpass of 0.2-3.5 keV and was one of two detectors onboard used for imaging. During the Einstein lifetime more than 4000 targets were observed with the IPC.


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 screening process for the Einstein IPC data excluded the outer regions of the detector and periods of poor aspect solution or high background. Since these excluded data may still be useful in some cases, the unscreened data files include the full photon data.

Each entry in this database has associated with it 4 data files in FITS format and one in ascii. The FITS files are : the unscreened photons list ('up'), the source detection file ('sd'), the barycenter timing file ('bt') and the background file ('bk'). The ascii file ('ls') contains a summary of the observation.

The 'up' file contains seven extensions, including an observation log, good time intervals, and an event table. The 'sd' contains a minimum of four extensions, which store the information about the detected sources, and in addition there are two extensions for each detected source containing the spectrum. The 'bt' file has three extensions, which include the solar system barycenter time correction and ephemeris.

This database table uses the information stored in the keywords of the EVENT extension FITS file ('up'). The following keywords were utilized: DATE_OBS TIME-OBS, DATE_END TIME-END, NAXIS2, RA_NOM DEC_NOM, OBJECT, OBJCLASS, OBS_ID, TITLE, ONTIME.


Parameters

Name
Name of target as given in the OBJECT keyword of the event FITS extension.

Start_Time
Observation start time.

End_Time
Observation stop time

Nrows
Number of rows in the event extension. This corresponds to the number of photons detected in the observation.

RA
The Right Ascension of the nominal pointing in the selected equinox. The Right Ascension and the Declination are the content of the keywords RA_NOM and DEC_NOM in the Event extension. They give the nominal pointing direction of the spacecraft during the observation.

Dec
The Declination of the nominal pointing in the selected equinox. The Right Ascension and the Declination are the content of the keywords RA_NOM and DEC_NOM in the Event extension. They give the nominal pointing direction of the spacecraft during the observation.

LII
The Galactic Longitude of the nominal pointing direction of the spacecraft during the observation.

BII
The Galactic Latitude of the nominal pointing direction of the spacecraft during the observation.

Obj_Class
Broad classification of the object type. This is divided into the following 13 categories, and they are : AGN, Cluster of galaxy, Galaxy, Gamma Ray Source, Nebula, Solar System Object, Star, Star Cluster, Supernova Remnant, X-ray Source, Survey Field, ?, and no observation.

ObsID
This parameter contains the Einstein sequence number associated with the observation.

Title
The observation title as given in the TITLE keyword.

Ontime
This parameter contains the exposure time in seconds.

Class
The HEASARC class parameter as derived from the value in the Obj_Class parameter. There was not always a unique match to the HEASARC classes.

The HEASARC classes in the following cases were set according to the following:

  Unknown                  for Obj_Class ? and  No Observation
  Star Unclassified        for Obj_Class Star and Star cluster
  X-ray Binary             for Obj_Class X-Ray Source
  Diffuse X-ray emission   for Obj_Class Survey Field
  

Filename
Name of the FITS file containing the event list extension.


Contact Person

Questions regarding the IPCUNSCRND 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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