EXOFASTv2 -- Jason Eastman ([email protected]) An exoplanet transit and radial velocity fitting software package in IDL If you use this in a publication cite: https://arxiv.org/abs/1907.09480 and see acknowledgements.tex within this distribution.

A tutorial with exercises can be found here: https://docs.google.com/document/d/1H-HMe1No5B4JE93V9kSEW91uSIQcG2eUVScf037biZw/edit

For detailed installation directions (and directions for Windows), see https://docs.google.com/document/d/1kcm7_mgfoCdDx6lUeqUJdDkpxtejyTNQf3sIveq3lkk/edit

Installation instructions (linux/mac)#

License-free use still requires a (free) IDL installation and runs a pre-compiled version with the virtual machine. You still must follow the installation instructions below.

To install a free version of IDL:

Create an Harris Geospatial account here: https://www.harrisgeospatial.com/Company/Create-Account

When logged in, download the latest version of IDL for your platform from here: http://www.harrisgeospatial.com/MyAccount/Downloads.aspx

Note the IDL Astronomy library is required. If you don't already have it, install it from here: https://github.com/wlandsman/IDLAstro

You also need the Coyote library. If you don't already have it, install it here: http://www.idlcoyote.com/documents/programs.php#COYOTE_LIBRARY_DOWNLOAD

EXOFASTv2 is best installed with git

cd $HOME/idl git clone https://github.com/jdeast/EXOFASTv2.git

NOTE: EXOFASTv2 logs the version number used for each fit if installed with git and git is in your path (i.e., it can be invoked via "git").

define environment variables (bash shell, e.g., .bashrc)

export EXOFAST_PATH="$HOME/idl/EXOFASTv2/"

if IDL_PATH is not defined, add EXOFAST_PATH and subdirectories to the default IDL path

if [ -z "$IDL_PATH" ]; then export IDL_PATH="<IDL_DEFAULT>:+${EXOFAST_PATH}" else # otherwise, append EXOFAST_PATH and all subdirectories to your IDL_PATH export IDL_PATH="${IDL_PATH}:+${EXOFAST_PATH}" fi

this is only required if you want to use the BJD timing library

you may already have this defined for other libraries, in which

case you need not redefine it. However, it must contain

JPLEPH.405 and you must have write access here.

export ASTRO_DATA="${EXOFAST_PATH}/timing/"

--- OR ---

define environment variables (c shell, e.g., .tcshrc)

setenv EXOFAST_PATH "${HOME}/idl/EXOFASTv2/"

if IDL_PATH is not defined, add EXOFAST_PATH and subdirectories to the default IDL path

if ("$IDL_PATH" == "") then setenv IDL_PATH "<IDL_DEFAULT>:+${EXOFAST_PATH}" else # otherwise, append EXOFAST_PATH and all subdirectories to your IDL_PATH setenv IDL_PATH "${IDL_PATH}:+${EXOFAST_PATH}" endif

this is only required if you want to use the BJD timing library

you may already have this defined for other libraries, in which

case you need not redefine it. However, it must contain

JPLEPH.405 and you must have write access here.

setenv ASTRO_DATA "${EXOFAST_PATH}/timing/"

NOTE: If you have used the old version of EXOFAST, you must remove it from your IDL_PATH to run correctly.

To test your installation, try the HAT-3b example:

cd $EXOFAST_PATH/examples/hat3 idl -e "fithat3"

TIP 1: make your terminal wide so the MCMC updates don't spam the screen

TIP 2: If you don't care about the results, run a very short fit by setting maxsteps=100 (idl -e "fithat3, maxsteps=100"). This will give you a very imprecise/unreliable answer, but allow you to check your installation in ~5 seconds instead of ~45 minutes.

It will generate many output files ($EXOFAST_PATH/examples/hat3/HAT-P-3b.Torres.*) (see $EXOFAST_PATH/exofastv2.pro for an explanation of outputs). The last file it generates is HAT-3b.transits.tex. If that is generated without error, you're good to go!

To get future updates, simply type

cd $EXOFAST_PATH git pull

Troubleshooting

I try hard to test thoroughly before pushing new code (but I'm not perfect!). If it does not compile or you get a syntax error, it is very likely a problem with your setup. The most likely reasons are:

1. Your IDL_PATH or EXOFAST_PATH environment variables are not set up correctly. From a terminal, type "echo $IDL_PATH" (it should include EXOFASTv2) and "echo $EXOFAST_PATH" (it should point to your installation) to check.

2. You have missing dependencies (e.g., IDL astronomy library, coyote library)

3. You have programs with the same name with a higher precedence in your IDL path. Renaming or moving your version will fix it, but please send me an email if the conflicting code is a library routine. I will rename the EXOFASTv2 version to avoid conflicts with others.

4. You have an incompatible version of IDL. EXOFASTv2 has been built and tested on linux with IDL 8.5. I also typically perform a cursory test with a linux installation of IDL 6.4 (circe 2007). I am not aware of any incompatibility for any platform (Windows, Mac, Linux) or IDL versions newer than 5.0, but it has not been tested on anything older than 6.4. If you find any incompatibilites on any version, IDL 5.0 (circe 1997) or later, please let me know. This code relies heavily on pointers and structures, which were introduced in IDL 5.0. Older versions will never be supported.

Note 1: The latest IDL version can be installed for free and EXOFASTv2 can be run within a virtual machine without a license.

Note 2: The HAT-3 example runs to completion in GDL but many things are sub-optimal:

a) The results are unverified and many features are untested b) Limb darkening models outside of the grid are rejected a priori. c) Multi-page postscript files (chains, pdfs, models) are not supported in GDL. d) The covariance plot is disabled e) It is ~3.5x slower f) Error messages spam the screen

If you're interested in making it work better with GDL, please contact me.

5. I have introduced a bug. Even if your problem is not a bug, if you've read the documentation, given it some thought, and still can't figure it out, it's probably at least a failure in documentation. Send me an email -- [email protected]

Tips, Warnings and Caveats

Other examples are available for various use cases, which are intended to be templates for various types of fits, and includes an example of running EXOFASTv2 without an IDL license. See $EXOFAST_PATH/examples/README for more information.

Error checking is not thorough. You may encounter cryptic error messages and strange failure modes if you use it in a way it wasn't intended. Do not stray far from the examples blindly.

Do not ignore the warnings about the Gelman Rubin statistic without thoroughly inspecting the PDFs and chains.

If you're stuck, feel free to ask me for guidance.

This is a BETA version. EXPECT BUGS!!! And please report any unexpected behavior.

It is not fully documented. Please don't hesitate to email me with questions. See the $EXOFAST_PATH/examples directory for templates to get started on your own fits.

Major releases or bug fixes will be announced on twitter (@exofastupdates)