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I am trying to extract spectra from CTIO Hydra, which I have done many times before. I have now upgraded to the new IRAF v2.14 and am encountering a strange problem. If I run 'dohydra' on images which I have processed with 'ccdproc' for overscan subtraction and trimming (OT), it works fine. However, if I take 'ccdproc' one step further and do zero subtraction on the frames (OTZ), 'dohydra' then gives a floating point error. Doing 'imstat' on the images reveals no hint of strange pixel values.I also tried changing the pixel type parameter in the ccdred package to "real double". Doing this allows 'dohydra' to run, but at the aperture identification step it plots values that are either -1e19, 0, or +1e19. Again doing 'imstat' on the images reveals no such strange values.Any suggestions would be appreciated. Thanks.

Hi,I don't have an immediate answer. It would depend on how your are doing the extractions. If you send an lpar I might be able to say something. Mainly I would wonder if you use cleaning or the "optimal" weighting options that some numbers could become very small and the algorithm might be sensitive to this.Yours,
Frank Valdes

Thanks, Frank. Here is the lpar of the dohydra task and its associated additional 'params'. I don't think it has anything to do with cleaning because (a) I don't have those options turned on and (b) the crash occurs immediately upon running 'dohydra'. Thanks for your help.hydra> lpar dohydra
objects = "sflat321" List of object spectra
(apref = "Dflat") Aperture reference spectrum
(flat = "Dflat") Flat field spectrum
(throughput = "Dflat") Throughput file or image (optional)
(arcs1 = "tharlong") List of arc spectra
(arcs2 = "") List of shift arc spectra
(arcreplace = "") Special aperture replacements
(arctable = "") Arc assignment table (optional)\n
(readnoise = "3.") Read out noise sigma (photons)
(gain = "1.") Photon gain (photons/data number)
(datamax = 60000.) Max data value / cosmic ray threshold
(fibers = 131) Number of fibers
(width = 12.) Width of profiles (pixels)
(minsep = 6.) Minimum separation between fibers (pixels)
(maxsep = 20.) Maximum separation between fibers (pixels)
(apidtable = "bluecircle.iraf.1") Aperture identifications
(crval = "6390.") Approximate central wavelength
(cdelt = "0.0875") Approximate dispersion
(objaps = "") Object apertures
(skyaps = "") Sky apertures
(arcaps = "") Arc apertures
(objbeams = "0,1") Object beam numbers
(skybeams = "0") Sky beam numbers
(arcbeams = "") Arc beam numbers\n
(scattered = no) Subtract scattered light?
(fitflat = yes) Fit and ratio flat field spectrum?
(clean = no) Detect and replace bad pixels?
(dispcor = yes) Dispersion correct spectra?
(savearcs = yes) Save simultaneous arc apertures?
(skyalign = no) Align sky lines?
(skysubtract = no) Subtract sky?
(skyedit = no) Edit the sky spectra?
(saveskys = no) Save sky spectra?
(splot = no) Plot the final spectrum?
(redo = yes) Redo operations if previously done?
(update = yes) Update spectra if cal data changes?
(batch = no) Extract objects in batch?
(listonly = no) List steps but don't process?\n
(params = "") Algorithm parameters
(mode = "ql") hydra> lpar params
(line = INDEF) Default dispersion line
(nsum = 10) Number of dispersion lines to sum or median
(order = "increasing") Order of apertures
(extras = no) Extract sky, sigma, etc.?\n\n-- DEFAULT APERTUR
(lower = -5.) Lower aperture limit relative to center
(upper = 5.) Upper aperture limit relative to center\n\n-- A
(ylevel = 0.05) Fraction of peak or intensity for resizing\n\n-
(t_step = 10) Tracing step
(t_function = "spline3") Trace fitting function
(t_order = 3) Trace fitting function order
(t_niterate = 1) Trace rejection iterations
(t_low = 3.) Trace lower rejection sigma
(t_high = 3.) Trace upper rejection sigma\n\n-- SCATTERED LIG
(buffer = 1.) Buffer distance from apertures
(apscat1 = "") Fitting parameters across the dispersion
(apscat2 = "") Fitting parameters along the dispersion\n\n-- A
(weights = "none") Extraction weights (none|variance)
(pfit = "fit1d") Profile fitting algorithm (fit1d|fit2d)
(lsigma = 3.) Lower rejection threshold
(usigma = 3.) Upper rejection threshold
(nsubaps = 1) Number of subapertures\n\n-- FLAT FIELD FUNCTIO
(f_interactiv = yes) Fit flat field interactively?
(f_function = "legendre") Fitting function
(f_order = 1) Fitting function order\n\n-- ARC DISPERSION FUN
(threshold = 10.) Minimum line contrast threshold
(coordlist = "linelists$thar.dat") Line list
(match = 1.) Line list matching limit in Angstroms
(fwidth = 4.) Arc line widths in pixels
(cradius = 10.) Centering radius in pixels
(i_function = "spline3") Coordinate function
(i_order = 3) Order of dispersion function
(i_niterate = 2) Rejection iterations
(i_low = 3.) Lower rejection sigma
(i_high = 3.) Upper rejection sigma
(refit = yes) Refit coordinate function when reidentifying?
(addfeatures = no) Add features when reidentifying?\n\n-- AUTOMATI
(select = "interp") Selection method for reference spectra
(sort = "jd") Sort key
(group = "ljd") Group key
(time = no) Is sort key a time?
(timewrap = 17.) Time wrap point for time sorting\n\n-- DISPERSI
(linearize = yes) Linearize (interpolate) spectra?
(log = no) Logarithmic wavelength scale?
(flux = yes) Conserve flux?\n\n-- SKY SUBTRACTION PARAMETERS
(combine = "average") Type of combine operation
(reject = "avsigclip") Sky rejection option
(scale = "none") Sky scaling option
(mode = "ql")

Please see the lead article on the homepage for information about a critical update just released which may explain the error you are seeing. Please reinstall the binaries (a source update is not required) and let us know whether the problem continues.-Mike