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HRIPHOT: Help

HRIPHOT - Einstein HRI Photon Event Data


Overview

The HRIPHOT database contains information from the High Resolution Imager 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 High Resolution Imager has been described by Henry et al. (Proc SPIE, 106,196,1977).

Description

The HRI used a pair of cascaded microchannel plates as an X-ray image converter and photoelectron multiplier, and a crossed-wire grid as a two-dimensional position-sensitive charge detector. The detector provided an arrival time and position for each X-ray event occurring within the 24-arcmin FOV and within the energy range 0.15 to 3.5 keV. The spatial resolution of the HRI was 3 arcsec at the telescope focus and the temporal resolution was 7.8125 microsec. The nominal sensitivity of the HRI was 10 Uhuru counts per second, but this value depends on the assumed value of the low-energy cutoff parameter Ea. An Objective Grating Spectrometer (OGS) could be used in conjunction with the HRI. 53 sequences with this configuration are included in the 870 HRI photon events files of this database.

Data Products

The only data products associated with this database table are FITS events files. The file names for these data products have the format `hhhmmDdd.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., that is used 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.

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

File_Image
File name of the FITS events file in the data archive. The files have the format `hhhmmDdd.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 HRIPHOT 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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