xcsao Example 2. Emission and Absorption

In this example, we illustrate the variety of printed reports and graphical summaries available from xcsao. These can be used to get a feeling for the quality of the resulting redshift and to pass on xcsao results for use by other programs.
To obtain the redshift of a single galaxy, we will cross-correlate this one-dimensional spectrum, found in an IRAF multispec file named 1995.1122.0113.311.062165.ms.imh, against three template spectra. The parameters are set in xcsao.par. galaxy spectrum
The emission line template spectrum has been synthesized based on line positions from a wavelength table and mean widths from many emission line spectra taken by this instrument. synthetic emission line spectrum
This composite absorption line template spectrum was made by adding many continuum-subtracted spectra from a different instrument. composite absorption spectrum
This composite absorption line template spectrum was made by adding many spectra of NGC 7331 taken by this instrument. Note that there is an H alpha emission feature. composite absorption spectrum

Running xcsao

cl> xcsao 1995.1122.0113.311.062165.ms.imh
returns the following output if report_mode = 1: 
IRAF rvsao.xcsao 2.0b mink@xena Thu 12:14:58 10-Jul-97

1995.1122.0113.311.062165.ms Object: 311.062165 
RA: 08:13:29.34 Dec: 29:02:12.0 $.1f23-Nov-1995 10:37:37.00 =HJD2450044.9457 BCV:  25.30
3679.9A- 7551.7A 4096 points, filter: 5 20 125 250 apodize 0.05 fit 0.5 best 1
Temp:          femtemp vel:   0.00  tsh:   0.00 HCV:   0.00 Peak: 14415.3 h:0.950 R:  52.48 CZ: 14441.8 +/-  11.655 1 +tc
Temp:       fn7331temp vel: 796.90  tsh:   0.00 HCV:   0.00 Peak: 13564.6 h:0.507 R:   7.29 CZ: 14424.1 +/-  38.929 1 -el
Temp:            ztemp vel:   0.00  tsh:   0.00 HCV:   0.00 Peak: 14406.9 h:0.479 R:   6.67 CZ: 14433.4 +/-  26.785 1 -el -tf +tc
and this graph on the device specified by device. emission line correlation summary

Interacting with the Summary Display

If curmode is yes, the user can change the final display to discover more about the results.
Using the t command, the user can replot the summary page with a different template's cross-correlation. While the best match, template spectrum 1, is an artifically-created emission line template spectrum, the cross-correlation with template spectrum 2, a composite spectrum of a galaxy exhibiting absorption lines composite cross-correlation
and the cross-correlation with template spectrum 3, a composite template spectrum made from the spectra of several different galaxies. The shorter portion of the spectrum it covers is demarcated by the dashed lines in the summary page spectrum. composite template summary
After the command l (for lines) is typed, the spectrum is replotted with emission and absorption lines labelled at the velocity labelled by the asterisk (*). summary with labelled lines
The / command will expand the spectrum graph to cover the entire width of the display, with redshift velocity, error, and R-value displayed at the top and the lines still labelled. This display is also useful if you just want to have a graph of a spectrum with labelled lines. The o command can be used to label emission lines or absorption lines or both. spectrum with labelled lines
The z command can be used to check out specific regions of the spectrum, such as the region around the calcium H and K absorption lines or this region around the hydrogen alpha emission line. hydrogen alpha emission line.
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