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
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
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.
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
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
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.
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 (*).
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