iraf.net

It seems something has change in "scombine"I have done this so many times, but today it gives me a error:
cl> scom
List of input spectra (@list_NVir):
List of output spectra (NVir_com):
ERROR: parameter `snoise' not found
scombine ()I then did:
cl> lpar scom
input = "@list_NVir" List of input spectra
output = "NVir_com" List of output spectra
(noutput = "") List of output number combined spectra
(logfile = "STDOUT") Log file\n
(apertures = " ") Apertures to combine
(group = "apertures") Grouping option
(combine = "average") Type of combine operation
(reject = "none") Type of rejection\n
(first = no) Use first spectrum for dispersion?
(w1 = INDEF) Starting wavelength of output spectra
(w2 = INDEF) Ending wavelength of output spectra
(dw = INDEF) Wavelength increment of output spectra
(nw = INDEF) Length of output spectra
(log = no) Logarithmic increments?\n
(scale = "none") Image scaling
(zero = "none") Image zero point offset
(weight = "none") Image weights
(sample = "") Wavelength sample regions for statistics\n
(lthreshold = INDEF) Lower threshold
(hthreshold = INDEF) Upper threshold
(nlow = 1) minmax: Number of low pixels to reject
(nhigh = 1) minmax: Number of high pixels to reject
(mclip = yes) Use median in sigma clipping algorithms?
(lsigma = 3.) Lower sigma clipping factor
(hsigma = 3.) Upper sigma clipping factor
(rdnoise = "rdnoise") ccdclip: CCD readout noise (electrons)
(gain = "gain") ccdclip: CCD gain (electrons/DN)
(sigscale = 0.1) Tolerance for sigma clipping scaling correction
(pclip = -0.5) pclip: Percentile clipping parameter
(grow = 0) Radius (pixels) for 1D neighbor rejection
(blank = 0.) Value if there are no pixels
(flpar = no) flush pfile on assign?
(mode = "ql")
cl> There is no "snoise" in the parameter file. It is not in my .imh file either.
What is "snoise"? How do I add in?Thank for help.Ping Zhao Harvard-Smithsonian Center for Astrophysics
vox: 617-496-7582 60 Garden Street
fax: 617-495-7356 Cambridge, MA 02138 USA
zhao@cfa.harvard.edu