OrbFit is a software package used to determine the orbits of asteroids written by the OrbFit Consortium. But it’s very sparsely documented, and can be a little tricky to install, never-mind learning how to use it.
Here’s my guide to getting it to successfully install on my mac (macOS Sierra).
A Conda Environment with a Lovely Fortran Compiler
Anaconda/Miniconda are going to greatly reduce the headache of having to install OrbFit, so make sure you have one or the other installed on your mac. There are plenty of tutorials just a google away, the Anaconda docs are excellent and I even wrote up my own guide and tutorial here.
Once you have .*Conda installed, go ahead and create a new environment within which to install Orbfit. I’m calling mine orbfit5.0 in case I want install an older/newer version of OrbFit at any point.
$ conda create -n orbfit5.0
Fetching package metadata ...............
Solving package specifications:
Package plan for installation in environment /Users/Dave/anaconda/envs/orbfit5.0:
Proceed ([y]/n)? y
# To activate this environment, use:
# > source activate orbfit5.0
#
# To deactivate this environment, use:
# > source deactivate orbfit5.0
Now activate your new environment:
$ source activate orbfit5.0
As OrbFit is written in Fortran you will need a suitable compiler to install the code. Go ahead and install one into your environment:
$ conda install -c uvcdat gfortran
Fetching package metadata .................
Solving package specifications: .
Package plan for installation in environment /Users/Dave/anaconda/envs/orbfit5.0:
The following NEW packages will be INSTALLED:
cloog: 0.18.0-0
gfortran: 4.9.3-1 uvcdat
gmp: 6.1.0-0
isl: 0.15-0
mpc: 1.0.3-0
mpfr: 3.1.5-0
Proceed ([y]/n)? y
Typing gfortran -v reveals that I’ve just installed the gcc v4.9.3 version of the compiler. Yours maybe a more recent version.
Download
The next thing to do is download the Orbfit distribution. You can find the latest distribution here:
http://adams.dm.unipi.it/orbfit/OrbFit/
As of writing this tutorial, OrbFit v5.0.5 was the latest version, and you can download the compressed version of that distribution from here. Unpack the code somewhere sensible.
mkdir ~/Orbfit5.0
mv ~/Downloads/OrbFit5.0.5.tar.gz ~/Orbfit5.0
cd ~/Orbfit5.0
tar -xvf OrbFit5.0.5.tar.gz
Install
Configure and Make OrbFit
Once unpacked, jump into the directory, wherever you’ve placed it (let’s assume it’s on your desktop):
$ cd ~/Orbfit5.0
Configure make to perform an optimised compile with gfortran:
$ ./config -O gfortran
Next we have to tweak the Make flags so the compiler knows where to find the conda library files. Open the file ./src/make.flags and change the line FFLAGS= -O3 -I../include to FFLAGS= -O3 -I../include -Wl,-rpath,${CONDA_PREFIX}/lib.
Now you can compile the code:
$ make
If at any point in this stage you slip-up or something goes wrong, try a make clean and begin again from the start of the configure and make processed.
At this point you either want the add Orbfit’s ./bin directory to your path. Open your ~/.bashrc, or equivalent file for your shell, and append:
# ORBFIT
export PATH="$PATH:$HOME/Orbfit5.0/bin"
Building a JPL Ephemerides Binary
Before you can use any of the OrbFit programs we need to generate a binary JPL ephemeris file for your machine. To do this first connect to the JPL FTP site via the command-line or your favourite FTP client. The server URL is:
and the directory you want to download is /pub/eph/planets/ascii/de413
Once downloaded, copy the contents of this directory into src/jpleph:
$ cp de413/* src/jpleph/
And now combine these ascii files into one binary file:
$ cd src/jpleph/
$ cat header.413 ascp1900.413 ascp1925.413 ascp1950.413 ascp1975.413 ascp2000.413 ascp2025.413 | ./asc2eph.x
If successful you will see something like this:
...
1713 EPHEMERIS RECORDS WRITTEN. LAST JED = 2469808.50
STOP OK
and a non-zero sized JPLEPH file containing the combined JPL ephemerides:
$ ls -l JPLEPH
-rw-r--r--@ 1 Dave admin 13966960 7 Sep 15:10 JPLEPH
Move this file into Orbfit’s lib directory:
$ mv JPLEPH ../../lib/jpleph
Test the Install
The final task is to test your install. To do so make a directory somewhere called orbfit-workspace and change into it:
$ mkdir ~/Desktop/orbfit-workspace
$ cd ~/Desktop/orbfit-workspace
Now download the Lowell Observatory astorb flavour of orbital elements from here and uncompress.
wget ftp://ftp.lowell.edu/pub/elgb/astorb.dat.gz
gunzip astorb.dat.gz
Finally grab my template options file and dummy observation files from this gist (click on the ‘Download ZIP’ button). Now you should have 3 files in your workspace:
$ ls
astorb.dat
dummy.obs
orbfit-template-run-options.oop
Run the command orbfit.x and then give orbfit-template-run-options as the run name. You should see something like this:
$ orbfit.x
Run name =
orbfit-template-run-options
Run name = orbfit-template-run-options
JPL planetary ephemerides DE413
number of perturbers = 0
binary ephemerides file= CPV
perturbing asteroids used: none
ngr_opt = F
No .rwo file, reading .obs and/or .rad files.
input_obs: 1 obs in ./dummy.obs
Using .rwo file, but checking .obs,.rad for update.
input_obs: 1 obs from ./dummy.rwo
input_obs: 1 obs from ./dummy.obs
There are no updates in .obs or .rad files.
Scanning file "astorb.dat" (format: BA2)
Semimajor axis = 3.1166357900000001E+00 au
Eccentricity = 0.115222750000000
Inclination = 12.5288100000000 deg
Long. of node = 148.0323380000000 deg
Arg. of pericenter = 357.0506910000000 deg
Mean anomaly = 39.3705710000000 deg
Scanning file "astorb.dat" (format: BA2)
Semimajor axis = 3.1166357900000001E+00 au
Eccentricity = 0.115222750000000
Inclination = 12.5288100000000 deg
Long. of node = 148.0323380000000 deg
Arg. of pericenter = 357.0506910000000 deg
Mean anomaly = 39.3705710000000 deg
ORBFIT: propagation of orbital elements
write_elems: ndim.ne.nd 32767 6
write_elems: ndim.ne.nd 32767 6
ORBFIT: generating ephemerides
and you will find an ephemeris file has been created called orbfit-template-run-options.oep containing the following:
Ephemeris for object 1999
Origin of orbital elements: read from file "astorb.dat" at record 1999
Equatorial coordinates App. motion
Date Hour MJD RA DEC Mag Delta R SolEl Phase Glat RA*cosDE DEC
(UTC) (UTC) h m s d ' " (au) (au) (deg) (deg) (deg) arcsec/s arcsec/s
=========== ====== ============ ============= ============ ===== ======= ======= ====== ====== ===== ========== ==========
12 Jun 2017 0.000 57916.000000 10 34 12.030 +14 59 6.76 16.5 2.9078 2.7977 -73.7 20.4 55.9 1.1476E-02 -3.8280E-03
Ephemeris for object 1999
Origin of orbital elements: read from file "astorb.dat" at record 1999
Equatorial coordinates App. motion
Date Hour MJD RA DEC Mag Delta R SolEl Phase Glat RA*cosDE DEC
(UTC) (UTC) h m s d ' " (au) (au) (deg) (deg) (deg) arcsec/s arcsec/s
=========== ====== ============ ============= ============ ===== ======= ======= ====== ====== ===== ========== ==========
12 Jun 2017 0.000 57916.000000 10 34 12.030 +14 59 6.76 16.5 2.9078 2.7977 -73.7 20.4 55.9 1.1476E-02 -3.8280E-03
Job done. Coffee time.
If you want some more details on the Orbfit options see here.