Last modified: December 2022

AHELP for CIAO 4.15


Context: Tools::Response


Create a simple image of an RMF or ARF file


rmfimg infile outfile [arf] [arfout] [product] [verbose] [clobber]


A response matrix file (RMF) encapsulates the mapping between the physical properties of incoming photons (such as their energy) and their detected properties (such as detector pulse heights or PHA) for a given detector. For X-ray spectral analysis, the RMF encodes the probability R(E,p) that a detected photon of energy E will be assigned to a given channel value (PHA or PI) of p. The standard Legacy format (see the GSFC HEASARC journal Legacy, issue no. 2) for the RMF uses a binary table in which each row contains R(E,p) for a single value of E as a function of p. Non-zero sequences of elements of R(E,p) are encoded using a set of variable length array columns. This format is compact but hard to manipulate and understand.

The rmfimg tool converts this format to a simple 2-dimensional image of R(E,p) versus E and p, allowing one to visualize the response of the instrument.

The tool works best on an RMF that was created with a uniform grid. It will create an image of an non-uniformly-gridded file, but the WCS in the output will be incorrect.

An ancillary response file (ARF) contains the effective area A(E) including the probability that a photon of energy E will be detected at all. The total `response' is A(E)R(E,p). The Legacy format for ARF is a binary table of A(E) versus E. To make it easy to visualize A(E) together with R(E,p), rmfimg optionally allows you to create a two-dimensional `ARF image' A(E,p), which just replicates A(E) for each value of p. Optionally, the output RMF image will be multiplied by the ARF to give an image of the total response.


Example 1

(1) rmfimg rmf.fits rmf.img

Makes an image from a Legacy RMF file.

Example 2

(2) rmfimg rmf.fits rmf.img arf=arf.fits arfout=arf.img product=no

As above, but also makes an ARF image from arf.fits.

Example 3

(3) rmfimg rmf.fits rsp.img arf=arf.fits arfout=arf.img product=yes

Makes response image rsp.img containing A(E)*R(E,p) (since product=yes) from rmf.fits and arf.fits. Also makes ARF image.

Example 4

(4) rmfimg "rmf.fits[bin energy=8,pi=2]" bin_rmf.img

Makes image from rmf.fits, binning axes by the given factor Only the names "ENERGY", "PHA", and "PI" are recognized, and only a single value representing the binning factor may be given; full DM rebinning syntax of the form start:stop:step is NOT supported. This functionality allows you to make a reasonable size image from a large RMF file.


name type ftype def min max reqd
infile file input       yes
outfile file output       yes
arf file input        
arfout file output        
product boolean   no      
verbose integer   0 0 5  
clobber boolean   no      

Detailed Parameter Descriptions

Parameter=infile (file required filetype=input)

Input Legacy RMF FITS file, possibly with binning expression.

Input RMF file.

The tool works best on an RMF that was created with a uniform grid. It will create an image of an non-uniformly-gridded file, but the WCS in the output will be incorrect.

Parameter=outfile (file required filetype=output)

Output RMF or response image.

Parameter=arf (file filetype=input)

Input ARF file, optional.

Parameter=arfout (file filetype=output)

Output ARF image, if input ARF file is supplied.

Parameter=product (boolean default=no)

If product is yes, the main output is a response image containing the product of RMF and ARF.

Parameter=verbose (integer default=0 min=0 max=5)

Controls screen output information, value is 0 (no info) to 5 (most info).

Parameter=clobber (boolean default=no)

Clobber output if it exists? (yes/no)

Changes in CIAO 4.15



Requires a uniformly-gridded RMF

The output from mkrmf works correctly as input to rmfimg.

See Also

acis_bkgrnd_lookup, acis_fef_lookup, acis_set_ardlib, addresp, aprates, asphist, combine_grating_spectra, combine_spectra, dither_region, dmarfadd, dmextract, eff2evt, fullgarf, hrc_bkgrnd_lookup, make_instmap_weights, mean_energy_map, mkacisrmf, mkarf, mkexpmap, mkgarf, mkgrmf, mkinstmap, mkpsfmap, mkrmf, mkwarf, psextract, psf_project_ray, readout_bkg, rmfimg, sky2tdet, specextract