Line Fitting



 

Line Fitting is done at two points in the spectroscopic pipeline;  The first time it is done as part of finding emission lines in order to measure an emission line redshift, secondly after the redshift has been determined,  all possible lines in the line list are measured.

These line lists are identified in the science archive as 'found' and 'measured'  people wishing to retrieve line parameters should go to the 'measured' list.  One further caveat the value of chi2 should be checked for each line in order to make sure that the pipeline was able to converge on a reasonable fit.

To the right is the line list used, the colored lines are used in the emission line redshift routine.  The lines in red are searched for in qsos, those in blue for galaxies, and those in green for both galaxies and qsos.

Note: Wavelengths are in vacuum.  For a number of qso lines the wavelength used is not the rest wavelength, but the position of those lines in the composite qso template, where the OIII lines were assumed to be at the restframe of the qso.

Line
Identifier
Wavelength
OVI 1033 1033.30
Lya 1215 1215.24 
NV 1239 1239.42
OI 1306 1305.53
CII 1336 1335.52
SiIV 1398 1397.61
SiIV+OIV 1400 1399.8
CIV 1546 1545.86
HeII 1638 1637.85
OIII 1666 1665.85
AlII 1857 1857.4
CIII 1908 1908.27
CII 2326 2326.0
NeIV 2439 2439.5
MgII 2800 2800.32
NeV 3347 3346.79
NeV 3427 3426.85 
OII 3728 3728.30
HeI 3889 3889.0
He 3971 3971.19
SII 4072 4072.3
Hd 4103 4102.89
Hg 4342 4341.68
OIII 4364 4364.436
Hb 4863 4862.68
OIII 4933 4932.603
OIII 4960 4960.295
OIII 5008 5008.240
OI 6302 6302.046
OI 6366 6365.536
NI 6529 6529.03
NII 6550 6549.86
Ha 6565 6564.61
NII 6585 6585.27
SII 6718 6718.29
SII 6733 6732.67
K 3935 3934.777
H 3970 3969.588
G 4306 4305.61
Mg 5177 5176.7
Na 5896 5895.6