linespec Example

Galaxy Emission Template at Zero Redshift

Create a template spectrum from 3000 to 8000 Angstroms using common galaxy emission lines at their rest wavelengths for use by the IRAF xcsao cross-correlation task. The wide range is specified because xcsao starts correlating using the overlap regions between the template and object spectra. The lines are initially computed with a 1-pixel half-width at half-max, the default when the individual widths are unspecified, in this case, 0.25 Angstrom. That initial spectrum is then convolved with a Gaussian filter with the instrument resolution of 2.0 Angstroms, and the resulting spectrum is written to the file emtemp2a.

A file, rvsao$lib/emtemp.dat contains this list of emission lines:

2798.00 0.0  10 MgII
3727.30 0.0  10 OII
4861.33 0.0  50 Hb
5006.84 0.0  30 OIII
4958.91 0.0  16 OIII
6300.23 0.0  10 OI   NOTE - this is telluric if Z=0.0 !
6562.82 0.0 100 Ha
6583.57 0.0  50 N2
6548.06 0.0  10 N1
6717.00 0.0  10 S1
6731.30 0.0  10 S2

When run with this parameter file the following output is written to the file(s) specified by logfiles:

rv> linespec emtemp.dat emtemp2a
IRAF rvsao.linespec 2.0b mink@xena Mon 13:27:35 19-May-97
3000.000A - 8000.000A by 0.250A: 20001 points in spectrum
Spread by 2.00A

 MgII 2798.00 2798.00 20.00 0.25 0.00 0.00 12.53 1.000
  OII 3727.30 3727.30 20.00 0.25 0.00 0.00 12.53 1.000
   Hb 4861.33 4861.33 10.00 0.25 0.00 0.00 6.27 1.000
 OIII 4958.91 4958.91 16.00 0.25 0.00 0.00 10.03 1.000
 OIII 5006.84 5006.84 30.00 0.25 0.00 0.00 18.80 1.000
   OI 6300.23 6300.23 10.00 0.25 0.00 0.00 6.27 1.000
   N1 6548.06 6548.06 10.00 0.25 0.00 0.00 6.27 1.000
   Ha 6562.82 6562.82 100.00 0.25 0.00 0.00 62.67 1.000
   N2 6583.57 6583.57 50.00 0.25 0.00 0.00 31.33 1.000
   S1 6717.00 6717.00 10.00 0.25 0.00 0.00 6.27 1.000
   S2 6731.30 6731.30 10.00 0.25 0.00 0.00 6.27 1.000

After the initial spectrum, with thin lines, is displayed,

the final spectrum, with fatter lines, determined by the resolution of the spectrograph, is shown.

That spectrum, with a header describing the inserted lines, is written to emtempwa.imh:

Use EMSAO to Find the Emission Lines

Last updated May 19, 1997 by Doug Mink dmink@cfa.harvard.edu

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