iraf.net

Dear all,

I am trying to remove the cosmics in my 1D spectra and I wanted to use lacos_spec. These are my inputs:

Image Reduction and Analysis Facility
PACKAGE = stsdas
TASK = lacos_spec

input = SCI_SLIT_FLUX_MERGE1D_NIR_0000.fits[0] input spectrum
output = SCI_SLIT_FLUX_MERGE1D_NIR_0000_clean.fits cosmic ray cleaned output s
outmask = SCI_SLIT_FLUX_MERGE1D_NIR0063.pl output bad pixel map (.pl)
(gain = 2.) gain (electrons/ADU)
(readn = 6.) read noise (electrons)
(xorder = 7) order of object fit (0=no fit)
(yorder = 3) order of sky line fit (0=no fit)
(sigclip= 4.5) detection limit for cosmic rays (sigma)
(sigfrac= 0.5) fractional detection limit for neighbouring pixe
(objlim = 1.) contrast limit between CR and underlying object
(niter = 4) maximum number of iterations
(verbose= yes)
(mode = al)

I don't get a successful result and this is the error I get:

ERROR: Axis exceeds image dimension
"inter-,sample="*",nav=1,niter=3,grow=0,cursor="")"
line 127: /home/manjavacas/iraf/lacos_spec.cl
called as: `lacos_spec (mode=h)'

Does anyone know why is this happening?

Many thanks in advanced!

Elena.

I think the problem may be that the task is expecting a 2-D image (e.g. a long-slit spectrum) as input; Depending on your file then either extension zero is not an image (typically it is just header but depends on the instrument), or else it is an extracted 1-D spectrum and the task is failing when trying to fit the second axis. If you set the 'yorder' parameter to zero it should skip this step and may allow the task to proceed.

If the data are already extracted you might just try using SPLOT to remove the cosmic rays manually, but I think I may not be understanding the input properly.

Many thanks!!

That work out for my 2D spectrum, but not for my 1D spectra (I changed ) yorder =0. When I put my 1D spectra I get:

_______________________________ Iteration 1 ___________________________________


Convolving with Laplacian kernel

Error convolving image: lacos9351kd
Warning: T_CONVOLVE: Kernel dimension higher than image dimension.
ERROR: Cannot open image (lacos9351ld)
"imreplace(lapla,0,upper=0,lower=INDEF)"
line 167: /home/manjavacas/iraf/lacos_spec.cl
called as: `lacos_spec (mode=h)'

Is there a easy way to solve it?

Many thanks in advanced!

I was afraid of that. The image is convolved with a 2x2 kernel later in the script. I think the only real difference between the "normal" lacos script and "spectroscopic" version is in how the CRs are detected, but the script expects a 2-D image nonetheless.