Find_Orb integration
Ephemeris Interpolator can import ephemerides generated by Find_Orb using the 
Add last ephemeris generated in Find_Orb button.
Find_Orb
Find_Orb is a free program written by Bill Gray which can take a set of observations of an asteroid, comet, or natural or artificial satellite and find a corresponding orbit. An ephemeris can then be generated. There is extensive documentation at these links:
- online Find_Orb : Orbit determination from observations: https://www.projectpluto.com/find_orb.htm.
- online Explanation of Find_Orb ephemeris details: https://www.projectpluto.com/eph_expl.htm
- online Command-line, non-interactive Find_Orb ('fo') usage: https://www.projectpluto.com/fo_usage.htm
Find_Orb needs to be installed locally for the integration to Ephemeris Interpolator to be used. Installation files are available via the Downloads section on the main documentation page at https://www.projectpluto.com/find_orb.htm#download.
Required settings for Find_Orb integration
The FindOrbPath setting must be set to the folder where Find_Orb outputs its ephemeris text file, normally the folder containing the Find_Orb program (find_o32.exe or find_o64.exe).
The ephemeris output text file name currently used by Find_Orb is "ephemeri.txt" and is the default name for the FindOrbEphFile setting. If this name changes in subsequent versions of Find_Orb then the FindOrbEphFile setting may need to be changed to match the new name.
Find_Orb ephemeris format
Ephemeris Interpolator attempts to recognise ephemerides by pattern matching an ephemeris line against an internal set of ephemeris formats. Find_Orb is capable of generating a large number of different ephemeris formats, see the Creating and saving an ephemeris section on the https://www.projectpluto.com/find_orb.htm page. Ephemeris Interpolator includes a set of ephemeris formats that match Find_Orb ephemerides generated with the following options when the M (Make ephemeris) Find_Orb command is used to specify the following options:
|
Description |
Equivalent EPHEM_OPTIONS (see below) |
|
|
A |
Alt/az output |
3 |
Z |
Apparent angular motion (default is total motion and PA) |
5 |
|
P |
Phase angle |
6 |
|
W |
Round to nearest step |
10 |
|
D |
Show ephemeris uncertainties |
16 |
1 |
Include RA/Dec |
(21=don't show) |
|
2 |
Include delta (distance from observer) |
(22=don't show) |
|
3 |
Include r (distance from Sun) |
(23=don't show) |
|
4 |
Include elongation from Sun |
(24=don't show) |
Ephemeris Interpolator includes separate formats to handle ephemerides generated with the above columns and with three types of time output (hours only, hours and minutes and hours, minutes and seconds).
Starting Find_Orb with default ephemeris parameters using a batch file (.bat)
To help standardise Find_Orb ephemeris output, Find_Orb can be started with parameters that set various ephemeris defaults. See a full description of the parameters in the environ.def text file in the Find_Orb program folder for more information.
The following parameters can be used:
|
Parameter |
Description |
|
EPHEM_START |
The starting time for ephemerides. Can be absolute, or relative to the current time, e.g. EPHEM_START=now-2h |
|
EPHEM_STEPS |
The number of ephemeris lines to be generated |
|
EPHEM_STEP_SIZE |
The ephemeris step size, e.g. EPHEM_STEP_SIZE=1h |
|
A list of numbers that correspond to the (generally alphabetic) values used to choose columns when the Make ephemeris command is used in the interactive Find_Orb. For a full list of numbers see the -E (options) section on the Find_Orb command line usage page at: https://www.projectpluto.com/fo_usage.htm. |
As an example, assuming that the 64-bit version of Find_Orb (find_o64.exe) is in a folder called C:\FindOrb, then putting these two lines into a text file and saving it with a .bat file extension, e.g. StartFO.bat would allow that file to be double clicked in Windows Explorer, or double clicked as a desktop shortcut to start Find_Orb with ephemeris options compatible with one of the default ephemeris formats contained in the Ephemeris Interpolator. Make sure the ephemeris options are all listed on the same line as the Find_Orb program name:
cd C:\FindOrb
find_o64.exe EPHEM_START=now-2h EPHEM_STEPS=12 EPHEM_STEP_SIZE=1h EPHEM_OPTIONS=3,5-6,10,15-16
This will start Find_Orb so that it will generate ephemerides starting 2 hours before the current time, with 12 lines of output and with a step size of 1 hour, including just the columns listed in the Make table and will also suppress unobservable ephemeris data (i.e. where the object is below horizon or the sun above) because 15 is included in the list of EPHEM_OPTIONS.
If different combinations of columns are required then use the Ephemeris Formats Editor to define those formats so they can be recognised correctly by the Ephemeris Interpolator.
FindOrbCombineAll setting
Allows astrometry retrieved from the MPC to be combined with astrometry for the same object but with a different identifier, as if the identifiers are all the same. See setting FindOrbCombineAll for further details.
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