FITS images of the IRTS/FILM 155 micron data.


1.FILM 155 micron continuum
This set of FITS files is the far-infrared continuum images at 155 micron, which were measured 
by the Far-infrared Line Mapper (FILM), one of the four focal plane instruments onboard the IRTS. 
The beam of the FILM 155 micron continuum channel was rectangle (FWHM) of 8' in the 
in-scan direction by 13' in the cross-scan direction. The spectrum resolution was 1.2 micron.

The data processing of the 155 micron data had been carried out by FILM members. The obtained typical rms error was 2x10^-7 W m^-2 sr^-1. 
There are striped patterns in the in-scan direction in each FITS image. The stripes are caused by the correction 
error for the change in the responsivity of FILM detectors, stressed Ge:Ga photoconductors. The absolute 
intensity calibration of the 155 micron data was based on the pre-launch test of the internal calibration 
light. The uncertainty of the absolute intensity was estimated in the range from -19% to +26%. 

The pointing information was determined using a star sensor (STS) instrument on board IRTS by 
collaborating with IPAC/NASA. The pointing accuracy obtained about within 1 arc-min. The position of 
the FILM was calculated as the distance between itself and the center of the IRTS was 1 degree. Since 
the distance has an uncertainty, a systematic pointing error may have crept into the FILM images 
within 4'-8'.


2. FITS image files
All data files are given in single FITS formats and are drawn on gnomonic projection with the galactic 
coordinate. The size of the images is 12.8 by 12.8 degrees with 4' pixels (192 x 192 pixels). Five kinds 
of FITS file are produced as follows (A--E).

A. film-155-ns/ssXX-raw.fits  (ns/ssXX_filmc1_flux.fits)
Average intensity images at 155 micron in W m^-2 sr^-1. Color correction procedures did not carry out 
for the data, because the FILM 155 micron observation was the narrow-band photometry.

B. film-155-ns/ssXX-err.fits  (ns/ssXX_filmc1_error.fits)
Standard deviations of the mean of the pixel.

C. film-155-ns/ssXX-smp.fits  (ns/ssXX_filmc1_no.fits)
The number of observations in pixel.

D. film-155-ns/ssXX-intp.fits  (ns/ssXX_filmc1_flux_intp.fits)
Average intensity and interpolated intensity data. The index of the interpolation procedure is described 
in files (E)

E. film-155-ns/ssXX-flug.fits  (ns/ssXX_filmc1_flag_intp.fits)
The number of the interpolation index for the files (D). The indexes are as follows:
	0: original average intensity.
	1: linearly interpolated from the nearest non-bad pixels within 3x3 box.
	2: non-linearly interpolated from the nearest non-bad pixels within 5x5 pixel circle.
	3: non-linearly interpolated from the nearest non-bad pixels within 7x7 pixel circle. 


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3/Mar/2001	By K.Okumura

Please send questions about the IRTS 155 micron images to 
oku@koala.ir.isas.ac.jp
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