read_image[/qualifiers] [image-name]
The image read becomes the current image. The following qualifiers specify the format of the image:
/fits - a FITS image (in the primary array) /rfits - a photon event file in FITS format (ROSAT RDF format) /EXO - EXOSAT image files /COMP - EXOSAT compressed image files (VMS only)The default assumes /fits.
The /exp_map qualifier indicates the image contains an exposure map and loads it into the exposure map arrays. It can be displayed using the disp/exp command.
File is in EXOSAT format. This is machine specific.
Image is in FITS format. This is machine independent.
File is in Einstein IPC xpr format. This is only supported under vms and is for expert use only.
File is FITS photon event format, using the format of the ROSAT Rev 0, 1 and 2 (RDF) defined by the US ROSAT data center and the HEASARC.
File is in exosat compressed format. This is machine specific and only works under VMS.
Load an image centered on x pixel n. The pixel value should be specified in the original 'standard' range used within a detector.
Loads an image centered on y pixel n. The pixel value should be specify in the original 'standard' range used within a detector.
Load an image centered on the specified r.a.. The value can be specified either as ra=``hh mm ss" (hour minute and second) or ra=deg.ddd (in degrees). It is assumed the current XIMAGE equinox for the specified r.a. (the command SHOW lists the current XIMAGE equinox, and the command CEY changes the current XIMAGE equinox).
Load an image centered on the specified dec.. The value can be specified either as dec=``deg mm ss" or ra=ddd.ddd (in degrees). It is assumed the current XIMAGE equinox for the specified r.a. (the command SHOW list the current XIMAGE equinox, and the command CEY change the current XIMAGE equinox).
Used to specify if coordinates are given as degrees value. This qualifier has been temporary inserted to interface with a grafical user interface, and it is not necessary if /RA and /DEC are specify in degress.
To specify the equinox for the requested coordinate image center, given using /RA and /DEC. By default the current XIMAGE equinox is assumed.
The qualifier /size=n specifies the image size in pixels. Only square images of size 8,16,32,64,128,256,512, or 1024 pixels are allowed.
If the size is given as a negative value, then it defines the size of the image in arc minutes. This is useful when overlaying or comaparing two images. Be warned that it will round this number to the closest even pixel.
As the image is read into memory it is rebinned by n bins. n is 1 or a multiple of 2 (the default is 1). This canbe used in combination with the /size qualifier to unzoom an image.
Allow to accumulate an image using the content of the DETX, DETY columns. Valid only for /RFITS format.
Only read the header of a FITS image. Image is not loaded.
The minimum of a range of acceptable values of PHA channels.
The maximum of a range of acceptable values of PHA channels.
The minimum of a range of acceptable values of PI channels.
The maximum of a range of acceptable values of PI channels.
The minimum time accepted. Available only for data in RFITS format. The time value should be given in the same format used in the TIME coumn of the fits file.
The maximun time accepted. Available only for data in RFITS format. The time value should be given in the same format used in the TIME coumn of the fits file.
(Not implemented yet). Allow to specify which image to read, if multiple images are stored in the primary header of a FITS file,
Allow to specify the filenmae of the image or event list using a qualifier instead of specifing the filename on the command line.
Allow to specify a spacial region file. The circle or box region file can be created using the command '/CIRCLE' and/or '/BOX'.
The '/time' qualifier allows to generate a time variability map obtained calculating the time chi-square distribution in a pixel. Chi-square values are stored in each pixel scaled from 0-200, values greater than 100 mean the source is probably variable. Its important to make sure there are a sufficient number of photons per bin, by heavily rebinning the image. To use this the event file must be time ordered.
The '/color' qualifier allows to generate a color weighted image obtained using the PI or a PHA column in an event list. In each pixel the energy information is summed and weighted by the number of photons. The resulting image is scaled from 0-100.
Examples:
read/fits/x=a/y=b/size=512 file-name ! decompress an image stored in
! file-name into an image
! centered on x=a,y=b and of
! size=512
read/rfits/min_pha=a/max_pha=b ! loads an image from a binary FITS
! events file including photons
! having pha channels within a and b.