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IPCPHOT: Help

IPCPHOT - Einstein IPC Photon Event Data


Overview

The IPCPHOT database contains information from the Imaging Proportional Counter aboard HEAO-2, the Einstein Observatory, in Event List Format. Einstein incorporated a high-resolution X-ray telescope and a focal plane assembly capable of positioning at its focus one of four instruments: a high-resolution imaging detector (HRI), a broader-field imaging proportional counter (IPC), a solid state spectrometer (SSS), and a Bragg crystal spectrometer (FPCS). Einstein (HEAO-2) was launched on November 13, 1978, and operated successfully until April 1981.

References

The Imaging Proportional Counter has been described by Gorenstein, et al. (TRANS. IEEE Nuc. Sci., NS-28 , 869, 1981), and by Giacconi, et al. (Ap.J. 230 , 540, 1979).

Description

The IPC is a flow type proportional counter that uses pulse rise time information from the induced cathode signal to determine the Y-Z coordinates of an event. There are two gas-filled counters with different thicknesses for detecting X-rays in the 0.2 to 3.5 keV region. The mirror ceases to reflect X-rays above about 4.5 keV. Time resolution is 63 microseconds. It has a 75 X 75 arcmin FOV with a spatial resolution of 1 arcmin, an effective area of 100 cm**2, and a sensitivity of 1 count per sec per UFU. The energy resolution (E/delta E) of the IPC was 0.5 at 0.25 keV and >1 at 1.5-4 keV. Background was 3 x 10**-3 cts arcmin**-2 sec**-1. For the instrument, the corresponding conversion factor was: 1 IPC ct s**-1 = 1 UHURU ct s**-1.

Parameters

Time
Start time of observation in the format yy.ddd

End_Time
Stop time of observation in the format yy.ddd

RA
The RA reference point value of the FITS image file. The right ascension (1950.0) in decimal degrees of the center of the image.

Dec
The DEC reference point value of the FITS image file. The declination (1950.0) in decimal degrees of the center of the image.

LII
Galactic Longitude of field center of the FITS image file.

BII
Galactic Latitude of field center of the FITS image file.

Roll_Angle
The detector roll angle in degrees

Photons
The number of photons collected during the exposure.

Ontime
Satellite On-Time (sec)

Mode
Observation mode of current observation (point, slew or scan)

Title
Information on the nature of the target. Entries include catalog names (e.g., 4U0248-85) and observer's notes.

XPR_File_Name
FITS keyword: HISTORY

The file name of the original XPR file used to create the FITS file. The XPR files conform to a standard of Ixxxx.XPR in which xxxx is the observation sequence number.

File_Image
File name of the FITS image file in the database system. The files have the format `ihhmmDdd.xp*`. The letters `hhmm` denote the RA hour and minute. The `D` is either `N` or `S` for North or South, and `dd` is the declination in degrees. The `*` is a letter such as A, B, C, etc., to distinguish the files when the rest of the file name is not unique. This occurs when more than one pointing was made at a given position.


Contact Person

Questions regarding the IPCPHOT 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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