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Final steps

If the extraction was performed on more than one image, the output spectra can be combined to form a single image with scombine.


You can rebin all the object spectra to the same wavelength ranges, if so desired. This makes them look a little nicer as you can chose the range to avoid points at the edges of the chip which are usually suspect anyway. Choose the wavelength limits by inspection with splot and then use scopy to create a new image:

scopy w1=3732.36 w2=7223.92 rebin=no

It may be worthwhile to remove any sky lines which dofibers has poorly dealt with at this stage. It is suggested that this is best done using fixpix. Given a pixel range to work with (determined by examination of the sky spectrum with implot) and the apertures to clean, fixpix interpolates across the sky-marred region. In general it does a pretty good job, but sometimes a significant feature is left. You can then either use fixpix again, enlarging the pixel ranges, or preferably, manually remove the feature with splot (use the ``x'' key to connect two cursor positions, or the ``j'' key to fudge a point to the cursor's y-value.)

cl> fixpix
Images to be modified (
Bad pixel regions file (STDIN):
310 316 1 92
364 368 1 92
432 437 1 92
443 449 1 92

You can use plot.gkimosaic to get plots of your spectra, which can be viewed in either soft or hard copy form. It is possible to have several spectra per page---advisable if you want a hard copy! Note that ``lwSchmidts'' is a local printer name at the Schmidt to specify narrow lines. Either use your local equivalent or the standard ``stdplot'' for hardcopy.

splot.options="auto wreset nosysid"
bplot >G
gkimosaic nx=3 ny=2 fill+ dev=stdgraph      #for a screen plot
gkimosaic nx=3 ny=2 dev=lwSchmidts    #for a hard copy

We have found the rvsao package from the Smithsonian Astrophysical Observatory Telescope Data Center ( very helpful for calculating radial velocities of galaxies measured with FLAIR. There are some galaxy templates suitable for use with rvsao.xcsao task in the FLAIR package; to use these in xcsao set the following parameters:


next up previous contents
Next: Acknowledgements Up: FLAIR IRAF Guide Previous: Spectral extraction: dofibers

Mon Aug 19 16:47:38 EST 1996