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Hi,I'm having problems extracting and dispersion correcting spectra in both echelle and slit form. I have just been working on a particular slit spectrum and I followed "A User's Guide to Reducing Slit Spectra with IRAF" on reducing spectra using the task doslit.I get as far as locating the aperture in the object spectrum without any problems, but after that I get an error message saying:ERROR on line 58: Arc reference spectrum not found - me_231.fitHowever, this file does exist and is in the same directory as the object spectrum. I run into similar problems when trying to work on echelle data.I'm running the EXPORT version of PC-IRAF v2.12 using Cygwin on a Win-XP machine.Conor

From the archive of mail:[quote:43c5efbf75]
NUMBER: 25
KEYWORDS: doslit, doecslit, dofiber, dohydra, doargus, dofoe, imtype
DATE: Fri Apr 15 10:56:47 MST 2005
FROM: valdesQ: I'm getting the error message: cc> doslit
List of object spectra (a0134):
Edit apertures for a0134? (yes):
ERROR on line 58: Arc reference spectrum not found - a0135
doslit () However, the file a0135.fits does exist. What's wrong?
A: This error is usually caused by a mismatch between the image extension
you have set as the default and the type of your data. Because
the installation default is "imh" but now it is more common to use
FITS files this mostly occurs when imtype="imh". You can change the
default imtype value by editing your login.cl, uncommenting the line
for imtype and changing the value to "fits" (or whatever
extension you use). This dependence on imtype is a "gotcha". The task needs to
manipulate the image names and uses the imtype variable to do
this. This is described in http://iraf.noao.edu/irafnews/apr98/irafnews.1d.html The reason this is not more general is that this program preceded
the changes which allowed people to use different image types and
the quick way to modify this complex task was to use the imtype
variable to tell the script what extensions to look for. I have made a changes to various related task to help with this
occasional "gotcha". The new behavior will be to show the full
name the task is looking for and to add a hint to check the imtype
variable. kp> doslit
...
ERROR on line 58: Arc reference spectrum not found - demoarc1.imh
Check setting of imtype
kp> dir demoarc1*
demoarc1.fits
[/quote:43c5efbf75]Note that if you really are using v2.12 on a Cygwin system then this must be the original Chris Burke port. The change mentioned above was done in 2005 and is part of v2.13. If you still have problems, post back.Cheers,
-Mike