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Name

lineid - Identify peaks in a spectrum and optionally find lines

Synopsis

lineid [parameter=value]

Description

lineid identifies peaks in a spectrum, and attempts to identify spectral lines. The units of the frequency axis will need to be specified (the default is GHz) in order for the line identification to work.

Operation can occur in several modes.
1. If the VLSR is given, a LineID is attempted. Either from a given restfreq, or from a linelist.
2. If the RESTFREQ is given, a VLSR is determined from the frequency of the fitted peak.
3. If neither is given, just the peak(s) are reported.

See also tablsqfit(1NEMO) with the option fit=peak, and ccdmom(1NEMO) has an algorithm to find (properties of) the Nth peak using mom=3,30,31,32,33,34

More sophisticated algorithms can be find in for example ADMIT’s LineID task.

Parameters

The following parameters are recognized in order; they may be given in any order if the keyword is also given. Use --help to confirm this man page is up to date.
in=
Input (table) file name. No default.
xcol=
X coordinate column, representing the frequency or wavelength axis. Units are GHz, unless specified with the xunit keyword. [1]
ycol=
Y coordinate column, reprepenting an intensity. [2]
xunit=
X axis unit (GHz, MHz, A, nm) -- not implemented yet. [GHz]
minchan=
Minimum channels for a peak [3] - not used yet
maxchan=
Maximum channels for a peak [] - not used yet
vlsr=
VLSR of object. Not set by default.
restfreq=
If line is known, give restfreq in xunits. Not set by default.
linelist=
Table with frequencies and lines. Not set by default.

Examples

The following example smoothes a set of random values by 10 channels to create a handful of peaks and investigates the strongest peak:

tabgen - 115 1 2 123 | tabsmooth - 1 12 10,5| lineid - 0 1
### nemo Debug Info: Peak: 40.1222 0.169591

tabgen - 115 1 2 123 | tabsmooth - 1 12 10,5| lineid - 0 1 vlsr=10000
### nemo Debug Info: Line at 40.1222, Look near freq = 41.5067 for a line

tabgen - 115 1 2 123 | tabsmooth - 1 12 10,5| lineid - 0 1 restfreq=115
### nemo Debug Info: Line at 40.1222 has z=0.651112 or vlsr=...

See Also

tablsqfit(1NEMO) , table(5NEMO)

admit::LineID_AT()

Author

Peter

Teuben

Update History


13-dec-2024    0.1 Draft created    PJT


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