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GUIDE: Grating User Interactive Data Extension

GUIDE is a software package for use within Sherpa to aid in identification of spectral lines and their use for deriving physical quantities.

Once in Sherpa, the import("guide") command gives access to the files in ATOMDB. See the GUIDE manual or online ahelp file for more info.

A number of useful commands are available to access the atomic database. Below we give a few simple examples: identify all lines near 1.85 Angstroms, give the strong lines for a 30 keV plasma, describe the O VIII transitions and reference data, and the ionbal for that transition at 3e7 K.

Identify all lines near 1.85 Angstroms:

sherpa> identify(1.85)
Lambda -- Ion UL - LL Emissivity@ kT RelInt For More Info
Angstrom ph cm^3/s keV
1.8504 Fe XXV 7- 1 4.57e-17 @ 5.437 1.000 describe(26,25,7,1)
1.8532 Fe XXV 10089- 6 1.06e-18 @ 3.431 0.023 describe(26,25,10089,6)
1.8554 Fe XXV 6- 1 8.39e-18 @ 5.437 0.183 describe(26,25,6,1)
1.8595 Fe XXV 5- 1 8.01e-18 @ 5.437 0.175 describe(26,25,5,1)
Give the strong lines for a 30 keV plasma:

sherpa> strong(30)
Assuming T = 30.000 is in keV
The listed "Approximate Emissivity" is scaled from the peak value
using the ratio of the ionization balance at the requested temperature
and the peak temperature for the line.

Approximate
Lambda -- Ion UL - LL Emissivity@ kT RelInt For More Info
Angstrom ph cm^3/s keV
1.5024 Fe XXVI 7- 1 1.89e-18 @30.000 0.176 describe(26,26,7,1)
1.7780 Fe XXVI 4- 1 1.07e-17 @30.000 1.000 describe(26,26,4,1)
1.7835 Fe XXVI 3- 1 5.12e-18 @30.000 0.478 describe(26,26,3,1)
1.8504 Fe XXV 7- 1 1.19e-18 @30.000 0.111 describe(26,25,7,1)
18.9671 O VIII 4- 1 1.17e-18 @30.000 0.109 describe(8,8,4,1)

Describe the O VIII transitions and reference data:

sherpa> describe(8,8,4,1)
Ion O VIII, energy level 1 ---
electron configuration : 1s~^2S_{1/2}
energy above ground (eV) : 0.000000
Quantum state : n=1, l=N/A, s=2, degeneracy=2
Energy level data source : 1983ADNDT..29..467S
Photoionization data source : 1964ApJS....9..185B
-------------------------------------------
Ion O VIII, energy level 4 ---
electron configuration : 2p~^2P_{3/2}
energy above ground (eV) : 653.078979
Quantum state : n=2, l=1, s=2, degeneracy=4
Energy level data source : 1983ADNDT..29..467S
Photoionization data source : 1964ApJS....9..185B
-------------------------------------------
Ion O VIII, 1 - 4 interactions ---
Electron collision rate from 1 -> 4 : nonzero.
Reference bibcode : 1983ADNDT..29..467S
Wavelength (lab/observed) (Angstrom) : 18.967110 +/- 0.000090
Wavelength (theory) (Angstrom) : 18.986200
Transition rate/Einstein A (s^-1) : 1.262440e+12
Wavelength (lab/observed) reference : 1977JPCRD...6...3E
Wavelength (theory) reference : 1983ADNDT..29..467S
Transition rate reference : 1987JPhB...20.6457F

Give the ionbal (ionization balance) for the O VIII transition at 3e+07 K:

sherpa> ionbal(8,8,3e7)
0.002448