This form can be used to run ATRAN in order to compute a synthetic
(i.e., theoretical) spectrum of atmospheric transmission. ATRAN was developed and kindly
provided to the SOFIA program by Steve Lord. The output data file generated
by ATRAN (atran.plt...dat), as well as a SM script to produce a plot (atran.plt...sm),
can be saved to your machine from your browser window once the program
has been run.
Give the altitude of the observatory in feet. ATRAN will use a model of the atmosphere to
compute the predicted water vapor overburden at the zenith. If you wish to change the
zenith water vapor content to a specific value, give the new value in microns in the
appropriate field; otherwise leave the value at 0 and ATRAN will use the predicted value
derived from the model. Specify the zenith angle for the observations and the
wavelength range of interest, in terms of the minimum and maximum wavelengths given in
microns. The minimum wavelength possible is 0.85 microns. (Note that the larger the wavelength
range chosen, the longer it takes to perform
the calculations.) A comment can be added to the output files, but is not necessary. Note
that although this version of ATRAN allows the user to specify the latitude of the observatory,
experience has shown that the day/night and seasonal variations in ozone are larger than
the latitude dependence in the total ozone column. Therefore, we recommend users adopt the
latitude of 39 degrees, in which case ATRAN will use a `standard' ozone value to compute the
atmospheric transmission model.
Note: In order to prevent form time-outs and the generation of huge output files, we have
restricted the maximum size of the wavelength range to be 40% of the central wavelength.
The reference for ATRAN is Lord, S. D., 1992, NASA Technical Memorandum 103957.
The current version uses the 2000/2001 version of the HITRAN database.
If you have problems with this form, please contact Bill Vacca (wvacca@mail.arc.nasa.gov). If you have questions about ATRAN itself, or would like a copy of the documentation on ATRAN, please contact Steve Lord (lord_91106@yahoo.com).