NIST Queries (astroquery.nist
)¶
Tool to query the NIST Atomic Lines database (http://physics.nist.gov/cgi-bin/ASD/lines1.pl).
Getting started¶
This is a relatively simple module that you may use to query spectra from
NIST. All the results are returned as a Table
. To do this you
just need to specify the lower and the upper wavelength for the spectrum you
want to fetch. These wavelengths must be specified as an appropriate
Quantity
object, for instance having units of
nanometer, or angstrom or the like. For example, to use a lower wavelength
value of 4000 Angstroms, you should use `4000 * u.AA`
and if you want the
same in nanometers, just use `400 * u.nm`
. Of course there are several optional
parameters you can also specify. For instance use the linename
parameter to
specify the spectrum you wish to fetch. By default this is set to “H I”, but
you can set it to several other values like “Na;Mg”, etc. Lets now see a simple example.
>>> from astroquery.nist import Nist
>>> import astropy.units as u
>>> table = Nist.query(4000 * u.AA, 7000 * u.AA, linename="H I")
>>> print(table)
Observed Ritz Rel. Aki Acc. ... Lower level Upper level Type TP Line
------------- ------------- ------ ---------- ---- ... ------------------- ------------------- ---- ----- --------
-- 4102.85985516 -- 4287700.0 AAA ... -- -- -- -- --
-- 4102.86191086 -- 245010.0 AAA ... 2p | 2P* | 1/2 6s | 2S | 1/2 -- T8637 --
-- 4102.8632 -- -- -- ... | | | | -- -- c57
4102.86503481 4102.86503481 -- -- -- ... 2s | 2S | 1/2 6d | 2D | 5/2 E2 -- L11759
-- 4102.86579134 -- 2858300.0 AAA ... -- -- -- -- --
4102.86785074 4102.86785074 -- -- -- ... 2s | 2S | 1/2 6s | 2S | 1/2 M1 -- L11759
-- 4102.86807252 -- 2858400.0 AAA ... -- -- -- -- --
4102.892 4102.8991 70000 973200.0 AAA ... 2 | | 6 | | -- T8637 L7436c29
-- 4102.8922 -- -- -- ... | | | | -- -- c58
-- 4102.92068748 -- 5145000.0 AAA ... 2p | 2P* | 3/2 6d | 2D | 5/2 -- T8637 --
-- 4102.9208 -- -- -- ... | | | | -- -- c59
-- 4102.92144772 -- 857480.0 AAA ... -- -- -- -- --
-- 4102.92350348 -- 490060.0 AAA ... 2p | 2P* | 3/2 6s | 2S | 1/2 -- T8637 --
-- 4341.647191 -- 7854800.0 AAA ... 2p | 2P* | 1/2 5d | 2D | 3/2 -- T8637 --
-- 4341.6512 -- -- -- ... | | | | -- -- c60
... ... ... ... ... ... ... ... ... ... ...
6564.522552 6564.522555 -- 53877000.0 AAA ... 2p | 2P* | 1/2 3d | 2D | 3/2 -- T8637 L2752
-- 6564.527 -- -- -- ... | | | | -- -- c67
-- 6564.535 -- -- -- ... | | | | -- -- c68
6564.537684 6564.537684 -- 22448000.0 AAA ... 2s | 2S | 1/2 3p | 2P* | 3/2 -- T8637 L6891c38
-- 6564.564672 -- 2104600.0 AAA ... 2p | 2P* | 1/2 3s | 2S | 1/2 -- T8637 --
-- 6564.579878 -- -- -- ... 2s | 2S | 1/2 3s | 2S | 1/2 M1 -- --
-- 6564.583 -- -- -- ... | | | | -- -- c66
6564.584404 6564.584403 -- 22449000.0 AAA ... 2s | 2S | 1/2 3p | 2P* | 1/2 -- T8637 L6891c38
6564.6 6564.632 500000 44101000.0 AAA ... 2 | | 3 | | -- T8637 L7400c29
-- 6564.608 -- -- -- ... | | | | -- -- c69
6564.66464 6564.66466 -- 64651000.0 AAA ... 2p | 2P* | 3/2 3d | 2D | 5/2 -- T8637 L2752
-- 6564.6662 -- -- -- ... | | | | -- -- c71
-- 6564.667 -- -- -- ... | | | | -- -- c70
-- 6564.680232 -- 10775000.0 AAA ... 2p | 2P* | 3/2 3d | 2D | 3/2 -- T8637 --
-- 6564.722349 -- 4209700.0 AAA ... 2p | 2P* | 3/2 3s | 2S | 1/2 -- T8637 --
Note that using a different unit will result in different output units in the
Observed
and Ritz
columns.
There are several other optional parameters that you may also set. For instance
you may set the energy_level_unit
to any one of these values.
'R' 'Rydberg' 'rydberg' 'cm' 'cm-1' 'EV' 'eV' 'electronvolt' 'ev' 'invcm'
Similarly you can set the output_order
to any one of ‘wavelength’ or
‘multiplet’. A final parameter you may also set is the wavelength_type
to one of ‘vacuum’
or ‘vac+air’. Here is an example with all these parameters.
>>> from astroquery.nist import Nist
>>> table = Nist.query(4000 * u.nm, 7000 * u.nm, 'H I',
... energy_level_unit='eV', output_order='wavelength',
... wavelength_type='vacuum')
>>> print(table)
Observed Ritz Rel. Aki ... Upper level Type TP Line
-------- ----------- ----- --------- ... ------------------- ---- ----- ----
-- 4020.871 (200) 5526.5 ... -- -- -- --
-- 4052.18664 -- 1238100.0 ... 5d | 2D | 3/2 -- T8637 --
-- 4052.19376 -- 737160.0 ... 5p | 2P* | 3/2 -- T8637 --
-- 4052.22121 -- 215030.0 ... -- -- -- --
-- 4052.23222 -- 737210.0 ... 5p | 2P* | 1/2 -- T8637 --
-- 4052.248747 -- 2412100.0 ... -- -- -- --
-- 4052.24892 -- 1485800.0 ... -- -- -- --
-- 4052.26147 -- 18846.0 ... 5p | 2P* | 3/2 -- T8637 --
... ... ... ... ... ... ... ... ...
-- 5525.19 (150) 2470.9 ... -- -- -- --
-- 5711.464 (180) 3515.8 ... -- -- -- --
-- 5908.22 (540) 70652.0 ... 9 | | -- T8637 --
-- 5956.845 (210) 5156.2 ... -- -- -- --
-- 6291.918 (250) 7845.7 ... -- -- -- --
-- 6771.993 (300) 12503.0 ... 12 | | -- T8637 --
-- 6946.756 -- 688.58 ... -- -- -- --