Access to Astronomical Catalogues

← Click to display the menu
VI/119       High accuracy computed water line list - BT2     (Barber+, 2006)

A high accuracy computed water line list - BT2. Barber R.J., Tennyson J., Harris G.J., Tolchenov R.N. <Mon. Not. R. Astron. Soc. 368, 1087 (2006)> =2006MNRAS.368.1087B
ADC_Keywords: Atomic physics Keywords: water - line list - BT2 - molecular spectra Abstract: A computed list of H2O infra-red transition frequencies and intensities is presented. The list, BT2 was produced using a discrete variable representation two-step approach for solving the rotation-vibration nuclear motions. It is the most complete water line list in existence, comprising over 500 million transitions (65% more than any other list) and is also the most accurate (over 90% of all experimental levels are within 0.3cm-1 of the BT2 values). Its accuracy has been confirmed by extensive testing against astronomical and laboratory data. The line list has been used to identify water lines in a variety of objects including: comets, sunspots, a brown dwarf and the nova-like object V838 Mon. Comparison of the observed intensities with those generated by BT2 enables physical values to be derived for these objects. The line list can also be used to provide an opacity for models of the atmospheres of M-dwarf stars and assign previously unknown water lines in laboratory spectra. Description: The data are in two parts. The first, the 'Levels File' (levels.dat) is a list of 221,097 energy levels, ordered by J and symmetry block. About 25,000 of these energy levels have been labelled with the appropriate angular momentum (J,Ka,Kc) and vibrational (v1,v2,v3) quantum numbers. The second part of BT2 is the 'Transitions File'. This has 505,806,202 entries. Each transition references upper and lower energy levels in the Levels File and gives the Einstein Aif coefficient for the transition. In uncompressed form the BT2 Transitions File is 12.6Gb of data. Therefore, in order to facilitate use of the list, the transitions have been ordered by frequency and separated into 16 smaller files, each representing a specific frequency range. These have labels of the form 02750-03500-BT2.txt where the two five digit numbers represent the lower and upper ends of the frequency range for that particular file. These files are zipped and need to be unzipped using the command 'bunzip2 filename'. In addition to the files containing the actual line list, we have provided a Fortran program, spectra-BT2.f90 that, when compiled on the user's computer, will produce an executable file. This will enable the user to generate emission or absorption spectra from BT2 by specifying various parameters including: temperature, frequency range, cut-off intensity and line width. There is also the facility to generate spectra with full ro-vibrational assignments if required. The method of using spectra-BT2 is detailed in the 'readme-spectra' file and there are also examples of a job file and an output file. It is ESSENTIAL to rename or else set up a symbolic link to the Levels File as: 'fort.80'. Also, spectra-BT2.f90 expects a single input transitions file, so if the frequency range required spans more than one of the frequency-ordered files, these must be concatenated to form a single file. In any event, it is ESSENTIAL to rename or else set up a symbolic link to the file containing the transitions as: 'fort.13' File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file 00000-00250-BT2.txt 24 17490214 Zipped files of frequency-ordered transitions. Once unzipped, use as 'fort.13' in spectra-BT2 00250-00500-BT2.txt 24 17022667 00250-00500 frequency-ordered transitions 00500-00750-BT2.txt 24 16530697 00500-00750 frequency-ordered transitions 00750-01000-BT2.txt 24 16098481 00750-01000 frequency-ordered transitions 01000-01500-BT2.txt 24 30866787 01000-01500 frequency-ordered transitions 01500-02000-BT2.txt 24 29161189 01500-02000 frequency-ordered transitions 02000-02250-BT2.txt 24 13954798 02000-02250 frequency-ordered transitions 02250-02750-BT2.txt 24 26727622 02250-02750 frequency-ordered transitions 02750-03500-BT2.txt 24 37249656 02750-03500 frequency-ordered transitions 03500-04500-BT2.txt 24 44635822 03500-04500 frequency-ordered transitions 04500-05500-BT2.txt 24 39325124 04500-05500 frequency-ordered transitions 05500-07000-BT2.txt 24 50083781 05500-07000 frequency-ordered transitions 07000-09000-BT2.txt 24 52289428 07000-09000 frequency-ordered transitions 09000-14000-BT2.txt 24 76679377 09000-14000 frequency-ordered transitions 14000-20000-BT2.txt 24 31640191 14000-20000 frequency-ordered transitions 20000-30000-BT2.txt 24 6050421 20000-30000 frequency-ordered transitions levels.dat 51 221097 File containing the 221,097 energy levels (some with ro-vibrational assignments). Once unzipped, use as 'fort.80' in spectra-BT2 readme-spectra 283 80 Explains possible settings for spec.job file spectra-BT2.f90 94 1328 Fortran code to be generate the spectra spec.job 158 8 A sample job file, to be modified as required (example of 6400-6460cm-1 in epsilon Indi)
See also: VI/121 : Energy level list and linelist of HCN/HNC (Harris+, 2006) VI/127 : High accuracy line list of HDO (Voronin+; 2009) Byte-by-byte Description of file: *-BT2.txt
Bytes Format Units Label Explanations
1- 7 I7 --- Level1 Reference level in Energy Level File 8- 14 I7 --- Level2 Reference level in Energy Level File 15- 24 E10.3 s-1 A Einstein A coefficient
Byte-by-byte Description of file: levels.dat
Bytes Format Units Label Explanations
1- 6 I6 --- Level [1,221097] Number of the level 8- 9 I2 --- J [0,50] Total angular momentum quantum number 11 I1 --- Sym [1,4] Symmetry bloc number (1) 13- 16 I4 --- Block Reference in the block 18- 30 F13.6 cm-1 E [0,30000] Energy of the level 32- 34 I3 --- v1 [-2,8] v1 symmetric stretch quantum number 36- 38 I3 --- v2 [-2,17] v2 bend quantum number 40- 42 I3 --- v3 [-2,7] v3 asymmetrics stretch quantum number 44- 45 I2 --- --- J (repeat of bytes 7-9) 47- 48 I2 --- Ka [-2,47] Ka rotational quantum number 50- 51 I2 --- Kc [-2,50] Kc rotational quantum number
Note (1): Symmetry block numbered as in Table 1 of paper: --------------------------------------------------------- J parity (even/odd) e e e e o o o o vibrational basis symmetry (q) e e o o e e o o rotational parity (p) e o e o e o e o ortho/para state (O/P) P O O P O P P O Symmetry Block number (code) 1 3 4 2 3 1 2 4 ----------------------------------------------------------
Contacts: R.J. Barber, bob(at) J. Tennyson, j.tennyson(at) G. J. Harris, greg(at)
(End) Bob Barber [Univ. Coll. London] 13-Jan-2006
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

catalogue service