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Hello,

I have lots of echelle data that I am in the process of reducing. I have gone through and used ecidentify to obtain an accurate wavelength solution from one night's data that I am using as the basis for the rest of my nights. I then have run ecreidentify on all my ThAr images, however, when I run dispcor to actually check that the solution is correct and that lines in my ThAr show up where they should, I find that they are not correct. They are typically off by about 1 angstrom. Does anyone know what could be causing this? I have listed below the lpar output for ecreid and dispcor. I have also listed the output of running ecreid.



--\$this->_split2($m[0]) lpar ecreid
images = "ThAr*" Spectra to be reidentified
reference = "arcnewref.ec" Reference spectrum
(shift = INDEF) Shift to add to reference features
(cradius = 2.0) Centering radius
(threshold = 45.0) Feature threshold for centering
(refit = yes) Refit coordinate function?
(database = "database") Database
(logfiles = "STDOUT,logfile") List of log files
(mode = "al")

--\$this->_split2($m[0]) lpar dispcor
input = "ThAr*" List of input spectra
output = "zThAr*" List of output spectra
(linearize = no) Linearize (interpolate) spectra?
(database = "database") Dispersion solution database
(table = "") Wavelength table for apertures
(w1 = INDEF) Starting wavelength
(w2 = INDEF) Ending wavelength
(dw = INDEF) Wavelength interval per pixel
(nw = INDEF) Number of output pixels
(log = no) Logarithmic wavelength scale?
(flux = no) Conserve total flux?
(blank = 0.0) Output value of points not in input
(samedisp = no) Same dispersion in all apertures?
(global = no) Apply global defaults?
(ignoreaps = no) Ignore apertures?
(confirm = no) Confirm dispersion coordinates?
(listonly = no) List the dispersion coordinates only?
(verbose = yes) Print linear dispersion assignments?
(logfile = "") Log file
(mode = "al")


Task ecreidentify is running...

ECREIDENTIFY: NOAO/IRAF V2.16 jeanm12@tequila.nmsu.edu Mon 19:46:51 28-Oct-2013
Reference image = arcnewref.ec, Refit = yes
Image Found Fit Pix Shift User Shift Z Shift RMS
ThAr.0018.ec 1348/1370 1348/1348 5.3 -38.9 -6.9E-5 0.00873
ThAr.0021.ec 1341/1370 1341/1341 4.77 -35. -6.2E-5 0.00797
ThAr.0022.ec 1344/1370 1344/1344 5.32 -39. -6.9E-5 0.00867
ThAr.0027.ec 1342/1370 1342/1342 5.09 -37.4 -6.6E-5 0.00878