Pan-STARRS Document Control PSDC-500-001-00 ___________________________________________________________________________ Pan-STARRS Project Management System Orbit Determination & Ephemeris Software Summary Jim Heasley & Robert Jedicke Pan-STARRS Moving Object Processing Systems Group Institute for Astronomy 15 April 2004 © Institute for Astronomy, University of Hawaii 2680 Woodlawn Drive, Honolulu, Hawaii 96822 An Equal Opportunity/Affirmative Action Institution Pan-STARRS Document Control PSDC-500-001-00 Revision History Revision Date Affected Explanation of Change Pages 00 15 April 2004 placed under PSDC 2 Pan-STARRS Document Control PSDC-500-001-00 Table of Contents Revision History ....................................................................................................................... 2 Table of Contents...................................................................................................................... 3 1 Executive Summary.......................................................................................................... 4 2 Introduction....................................................................................................................... 4 3 Software Packages............................................................................................................ 5 3.1 Orbfit......................................................................................................................... 5 3.2 ORSA........................................................................................................................6 3.3 FindOrb.....................................................................................................................6 3.4 CODES ..................................................................................................................... 8 3.5 Lowell Observatory Asteroid Ephemeris.................................................................. 8 3.6 JPL Ephemeris Service (Horizons)........................................................................... 9 3.7 Minor Planet Center (MPC)...................................................................................... 9 3.8 Tholen Routines...................................................................................................... 10 4 Recommendations........................................................................................................... 11 3 Pan-STARRS Document Control PSDC-500-001-00 Orbit Determination & Ephemeris Software Summary 1 Executive Summary PanSTARRS requires preliminary (or short-arc) orbit determination software (various modes of Gauss, Vaisala, and circular orbits), perturbative orbit determination software (initial and updating) with error determination and ephemeris generating software (with sky-plane error determination). Unfortunately, none of the publicly available orbit determination and ephemeris generating software packages satisfies all of PanSTARRS’s needs. Most can easily be excluded from consideration because they are unavailable, untested or unwieldy. The most likely candidates for PanSTARRS usage in order of decreasing utility in the opinion of the authors are OrbFit and Dave Tholen’s routines. A combination of the strengths of each might be a good starting point. The advantage of OrbFit is that it is a well respected and much used standard in asteroid and comet orbit determination and ephemeris generation software implemented on the AstDys website. The advantage of Tholen’s routines is that they are already maintained and supported by a dependable member of the PanSTARRS team. 2 Introduction PanSTARRS requires orbit determination and ephemeris generating software within the Moving Object (MO) pipeline and for offline analysis of MO data. Chesley has outlined the functionality of the MO pipeline in http://pan-starrs.ifa.hawaii.edu/project/workshops/dp_04_01_03/talks/ jedicke_neo_talk.pdf or .ppt. The orbit determination and ephemeris generating software is a relatively small (he estimated about 20%) component of the envisioned pipeline. It could be re-generated in-house but if publicly available software packages are sufficient for PanSTARRS’s purposes it would be economical to use them. At the very least it is prudent to survey what is currently available. This document summarizes the orbit determination and ephemeris generating software packages of which we are aware: Orbfit ORSA FindOrb CODES Lowell Observatory Asteroid Ephemeris JPL Ephemeris Service (Horizons) Minor Planet Center (MPC) Tholen Routines 4 Pan-STARRS Document Control PSDC-500-001-00 In Section 3 we provide (when available) the following information for each package when available: Package name Author(s) Website License/Availability Programming Language Current Version Level of Documentation Support Other Comments 3 Software Packages 3.1 Orbfit Package name: OrbFit Author(s): Andreas Milani ([email protected]) & OrbFit Consortium Website: http://newton.dm.unipi.it/orbfit/ License/Availability: Open source style arrangement Programming Language: Fortran 77 Current Version: 2.3.3 Level of Documentation: The source code is reasonably well commented so the purpose of most subroutines is clear. Some other small amounts of documentation are available. It is possible, but not easy to learn how to use the program using the available information. Support: The website invites requests for support but in my experience there has been no response to such requests or bug reports. Other: OrbFit is the software used to support the NEODys and AstDys data available on the Asteroid Services website at http://newton.dm.unipi.it. In one-on-one tests with the JPL ephemeris software the computed ephemerides are virtually indistinguishable. 5 Pan-STARRS Document Control PSDC-500-001-00 The software built easily "out of the box." The Solaris version did *not* operate properly, presumably due to a compiler incompatibility. A working code on Solaris was created using the gcc compiler and some modifications to the Makefile parmameters. The next release of OrbFit is advertised to be in Fortran 90. 3.2 ORSA Package name: Orbit Reconstruction, Simulation, and Analysis (ORSA) Author(s): Pasquale Tricarico ([email protected]) and others Website: http://orsa.sourceforge.net License/Availability: GPL Open Source Programming Language: C++ Current Version: 0.30 Level of Documentation: Virtually no useful documentation Support: Unknown Other: The package compiled properly after some work in terms of installing other software it requires. It does appear to execute under linux but with no documentation it is very difficult to assess whether it works as advertised. It purports to have or plan to implement much of the same level of analysis that OrbFit has, e.g., covariance matrices, collision predicting, etc. 3.3 FindOrb Package name: Find Orb 6 Pan-STARRS Document Control PSDC-500-001-00 Author(s): Bill Gray, Project Pluto [email protected]) Website: http://www.projectpluto.com License/Availability: Open source freely available for non- commercial use (DOS/Linux version only) Programming Language: C++ Current Version: Unknown, constantly under revision Level of Documentation: Source code is documented at some level. The web site gives some insights into the working of the program. Support: Bill Gray has been responsive to requests for help although he only seems interested in incorporating new features that are of interest to him. Other: FindOrb comes in two flavors: a Windows version and a DOS (or linux) version. The latter has been tested on a single case against the same set of input (synthetic) observations as OrbFit. The orbital elements derived were very similar and the forward projected ephemeris (6 months in time) were very close (order of an arcsecond). This is very interesting in that this simple code generally uses "fits" to the orbits of the major planets rather than the JPL ephemeris (although it can do so). Gray has taken some rather simple minded approaches to implementing methods described in some of the standard celestial mechanics textbooks. However, it would appear the proof is in the pudding -- at least in some cases this rather basic implementation works as nicely as OrbFit. It does not, however, have the analytical error analysis capability of the latter. Gray does seem to take the lead of some of the other packages, like OrbFit, and has implemented Monte Carlo error analysis. 7 Pan-STARRS Document Control PSDC-500-001-00 3.4 CODES Package name: Comet/asteroid Orbit Determination and Ephemeris Software (CODES) Author(s): Jim Baer ([email protected]) Website: http://users.stargate.net/~jimbaer/index.html License/Availability: Source available Programming Language: Java Current Version: 3.1 Level of Documentation: Web page fairly complete Support: unknown Other: This package is a GUI based orbit determination and analysis system. It claims to have much of the sort of sophisticated analysis found in OrbFit. This package has not yet been tested. 3.5 Lowell Observatory Asteroid Ephemeris Package name: Lowell Observatory Asteroid Ephemeris (ASTEPH) Author(s): Ted Bowell, Bruce Koehn Website: http://asteroid.lowell.edu License/Availability: Proprietary, availability unknown. Bowell has in the past indicated that his code was freely available. Programming Language: Unknown Current Version: 1.5 Level of Documentation: Unknown Support: My one "complaint" about its performance (it would only compute an ephemeris on full hour times) was acknowledged and I was