Eugene H. Avrett
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Cambridge, MA 02138
Pandora is a general-purpose non-LTE computer program for
calculating stellar atmosphere models and detailed line and continuum spectra.
The program was written by Eugene Avrett and Rudolf Loeser during more than 40
years, into early 2007. Gene Avrett devised and
Pandora's astrophysics and numerical methods, while
Rudy Loeser designed and built the program and superintended its actual
ongoing use until he retired. Most of the code development was done
VAX/VMS, although the code itself is
independent. The code was ported to
and finally to
Linux. Sylvain Korzennik helped the port
Linux and helps maintain the
providing some limited support.
Pandora supports ongoing research by Gene Avrett and his collaborators on
various specific problems of radiative transfer. Recent applications include
extensive modeling of the outer atmosphere of the Sun and other late-type
stars, including effects of mass flows; the atmospheric response to external
ionizing radiation; and the effects of ion diffusion.
Pandora can also be used
for simple illustrative studies of optically thick non-LTE spectral line
formation for different multilevel atoms and atmospheric models, using
plane-parallel and spherical geometries. The program output files include
extensive documentation and explanations of the computational procedures so
that the results are reasonably self-explanatory.
For an overall description of the program, see the document "Modeling with
Pandora", available as a
a PDF file.
An excellent set of lecture notes on "Radiative Transfer in Stellar
Atmospheres" by Robert J. Rutten can be found on his
web site . The "Astronomy course
material on radiative transfer and spectral line formation in stellar
atmospheres" is a graduate-level introduction to the subject and may serve as
a foundation for understanding the
You may also want to read Gene Avrett's
lecture notes "Introduction to non-LTE
Radiative Transfer and Atmospheric Modeling".
Computer-proficient researchers who understand basic stellar atmosphere theory
and modeling, and who are willing to make the effort to become successful
users, are welcome to obtain from CfA a version of
Pandora (see below).
Learning to use
Pandorasuccessfully generally requires some time and effort. You will need a Fortran compiler, some good understanding of radiative transfer, and the patience to read through the documentation. We do not have resources to provide user support.
Pandora is a non-interactive program written in Fortran77 over
more than 40 years of development. It compiles and runs successfully using
either the Intel or the Portland Group Fortran compilers (tested under Linux).
Procedures to build and run the program (using Linux), using either compilers,
are provided. The code should compile using any standard
compiler (under any OS), although run-time errors may occur (esp. for I/Os)
and the supplied scripts to drive the program may need to be adapted or
It does not compile with GNU's Fortran copmpiler (
although a skilled (and patient) programer could modify the code to teh
idiosycraties of the GNU compiler (the GNU consortium decided no to follow
decades of practice and have not implementeed things that all other commetial
compoiler do - you get what you pay for).
You can sample the flavor of the program by reading the following file.
Pandora running and to learn to use it, you can download
one of the available versions:
PandoraKIT: this is
Pandoraversion 78.018, as packaged by Rudy in April 2007.
The KIT is included here for historical reasons. Unless you have had experience with that KIT, we recommend that you use one of the RELEASES (see below).
This README file explains how to get started, while
the kit holds the the source and data
files you need, test runs, the manual, and a Unix script to generate an
executable program file (all in a 26MB tar-compress archive.)
The HOWTO file gives some additional explanations.
This KIT was set up by Rudy Loeser over a period of years. As far as
understanding and using it to get
Pandora up and running you're
on your own since Rudy has retired and is no longer available to help in any
way. A knowledge of
Un*x is necessary and you would benefit
from familiarity with your Fortran compiler.
PandoraRELEASES: Sylvain Korzennik helped port
Linuxand has reorganized the KIT to follow more standard
These releases come with
DETAILS files, and a
Makefile file to build
more easily the executables. They also come with documentation, test cases
(demos) and prebuild binaries.
This README file explains how to get and build a RELEASE.
Pandoraversion 78.018 with support scripts & demos v2.1.1.
Pandoraversion 79.009 with support scripts & demos v2.1.1 (partial release).
Pandora 78.018 is a stable version (2007),
79.009 is the latest version (2014) used for further code development.
The compressed tar-balls are available for download here.
Once you were able to build a functioning version of
Gene Avrett may be able to help with questions about the physical and
mathematical aspects of the program, and how to use it for empirical modeling.
He can be reached by e-mail at
Last modified: Wednesday, 06-Apr-2016 12:24:22 EDT