HRIIMAGE - Einstein HRI Images
FITS keyword: AVG_ROT
Average rotational offsets (in radians) from nominal pointing direction.
FITS keyword: GALB
Galactic Latitude of field center of the FITS image file.
FITS keyword: BSCALE
Array elements are converted to integers, scaled to +/- 32767. This is done by finding the maximum and minimum (datamax and datamin) and using the equation:
FITS keyword: CRVAL2
The DEC reference point value of the FITS image file. The declination (1950.0) in decimal degrees of the center of the image.
FITS keyword: CDELT2
The DEC increment along axis of the FITS image file.
FITS keyword: CDELT1
The RA increment along axis of the FITS image file.
FITS keyword: DATE_STP
Observation stop time.
FITS keyword: DATE
FITS image file creation date.
File name of the GIF file created from the FITS image file. The file names follow the format `*HhhmmDdd.gif`. The `*` is a letter such as A, B, C, etc., to distinguish the files when the rest of the file name is not unique. 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.
File name of the FITS image file in the database system. The files have been compressed with a routine called ZOO, so to separate the files from UNZOO'ed ones, the file has been renamed to the format `HhhmmDdd*.zoo`. 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.
File name of the decompressed (UNZOO'ed) FITS image file placed in the current directory. These file names are of the form `HhhmmDdd.xi*`. 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 trailing `XI*` signifies `X-ray Intensity` and the final letters such as A, B, C, etc. distinguish XI files when the rest of the file name is not unique. This occurs when more than one pointing was made at a given position.
FITS keyword: INSTRUME
Focal plane detector, usually `HRI` in this catalog.
FITS keyword: NH
Column density of neutral hydrogen in atoms/cm**2 integrated along the line of sight through our galaxy in the direction of the target.
FITS keyword: GALL
Galactic Longitude of field center of the FITS image file.
FITS keyword: DATAMIN
True minimum intensity within the FITS image file.
FITS keyword: NET_TIME
A measure of the effective exposure time for the field center. NET_TIME is the total number of seconds during which the detectors were able to gather data, corrected for Earth occultation, SAA, bad aspect solution and detector dead time.
FITS keyword: OBJECT
Object sequence number in the Einstein source catalog.
FITS keyword: OBSERVER
Party responsible for collecting this particular observation, where 0 = CFA, 1 = CAL, 2 = MIT, 3 = GSFC.
FITS keyword: DATAMAX
True peak intensity within the FITS image file.
FITS keyword: CRVAL1
The RA reference point value of the FITS image file. The right ascension (1950.0) in decimal degrees of the center of the image.
FITS keyword: ROLL_ANG
The angle in degrees which measures the roll of the spacecraft about an axis pointing toward the field center. A positive value indicates a clockwise rotation of the detector's FOV.
FITS keyword: CROTA2
FITS keyword: CROTA1
FITS keyword: DATE_OBS
Observation start time.
FITS keyword: TITLE
Information on the nature of the target. Entries include catalog names (e.g., 4U0248-85) and observer's notes.
FITS keyword: BZERO
`BZERO` is the offset to the true pixel values.
The true pixel value is found using the scaled value TAPE in the following equations:
TAPE = (TRUE - BZERO)/BSCALE TRUE = (TAPE*BSCALE) + BZERO
FITS keyword: CRPIX1
Pixel coordinates of `RA` in image center of the FITS image file. The RA reference pixel location.
FITS keyword: AVGOFFY
Average translation offsets (in 8 arcsec pixels) from nominal pointing direction on y axis.
FITS keyword: CRPIX2
Pixel coordinates of `DEC` in image center of the FITS image file. The declination reference pixel location.
FITS keyword: AVGOFFZ
Average translation offsets (in 8 arcsec pixels) from nominal pointing direction on z axis.