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ATOMDB File Formats

The ATOMDB contains three separate types of spectral output, in addition to the raw atomic data stored in FITS files in the APED directory (For a description of the atomic data formats used in APED, see this paper.) These three additional files, which are calculated by APEC, are:

Line Lists (grouped by temperature)

Files with the suffix _line.fits are FITS files with one block (HDU) for each temperature, along with an initial parameter block that gives the complete list of temperatures and densities found in the file. The data blocks contain the following columns:

Lambda The best available wavelength (in Angstroms)
Lambda_Err If available, the best estimate of the wavelength error (in Angstroms). If no value is available (ie, only theoretical calculations exist with no error estimate given), this is set to NaN
Epsilon The line emissivity at the temperature and density of the block (in photons cm^3 s^-1)
Epsilon_Err Available for future expansion; currently set to NaN.
Element The atomic number Z of the element
Ion The integer value of roman numeral describing the ion stage. I.e., 1 for a neutral ion, 2 for singly-ionized.
UpperLev The upper level of transition, keyed to the relevant energy level file in the APED.
LowerLev The lower level of transition, keyed to energy level file in APED.

Line Lists (grouped by line)

Files with the suffix _linelist.fits are FITS files with two data blocks, each with the same number of rows. The first block gives each line and its peak emissivity value, and the second block contains vector columns that give the values at each temperature and density. This is frequently the more useful file when browsing using prism. The columns in this file are:

Lambda The best available wavelength (in Angstroms)
Lambda_Err If available, the best estimate of the wavelength error (in Angstroms). If no value is available (ie, only theoretical calculations exist with no error estimate given), this is set to NaN
LambdaTh The theoretical wavelength; superceded by the value in Lambda if it is different.
dLambdaTh Error in the theoretical wavelength, iv available. If not available, set to NaN
Element The atomic number Z of the element
Ion The integer value of roman numeral describing the ion stage. I.e., 1 for a neutral ion, 2 for singly-ionized.
UpperLev The upper level of transition, keyed to the relevant energy level file in the APED.
LowerLev The lower level of transition, keyed to energy level file in APED.
ArraySize The number of elements in the temperature and emissivity vectors
PeakIndex The index of the peak emissivity in the emissivity vector.
Temperature Vector of temperatures, in Kelvin, with significant emission in the line.
Density Vector of densities with significant emission in the line
Emissivity Vector of emissivities (in photons cm^3 s^-1)
EmissivityErr Available for future expansion; currently set to NaN.

Compressed Continua

A compressed continuum file has a name ending in _coco.fits. and it contains the following columns:

Z The element's atomic number
rmJ The ion of interest, from the roman numeral value; ie 6 for VI
N_Cont The length of the continuum vector
E_Cont A vector containing energies, in keV, where the continuum value is calculated
Continuum A vector containing the continuum, in phot cm^3 s^-1 keV^-1, at the energies listed in the E_cont vector
Cont_Err currently not used
N_Pseudo The length of the pseudo-continuum vector; the pseudo-continuum consists of lines which are too weak to list individually and so are stored here so that they may contribute to the total spectrum without taking up too much space
E_Pseudo A vector containing energies, in keV, where the pseudo-continuum value is calculated
Pseudo A vector containing the pseudo-continuum, in phot cm^3 s^-1 keV^-1, at the energies listed in the E_cont vector
Pseudo_Err currently not used