Wiki source code of HG1G2 tools

Last modified by aipentti@helsinki_fi on 2024/01/09 08:29
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2 This page includes documentation and tools for //H//,//G//,,1,,,//G//,,2,, and //H//,//G//,,12,, photometric systems. These systems are empirical functions that are used to fit the observations (visual magnitudes) of asteroids as a function of the phase angle. The main purpose for these systems, together with the previous //H//,//G// system, is to predict the magnitude //H// of an asteroid at the exact backscattering direction as the phase angle is 0. This so-called absolute magnitude //H// is related to the size and albedo of an asteroid, and one of these three can be computed if the other two are known.
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4 The //H//,//G//,,1,,,//G//,,2,, system was chosen to replace the old //H//,//G// system as the tool recommended by the IAU at its general assembly in Beijing, August 2012. The system is described in [[Muinonen et al. (2010)>>doc:||anchor="ref"]]. For smooth adaptation of this system, we have implemented tools that can be used to fit observations with the //H//,//G//,,1,,,//G//,,2,, and //H//,//G//,,12,, functions. We are distributing so-called //reference implementations// of the system on different languages/platforms. The main idea is that they should all implement the same functionality, despite the programming language or computing platform.
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6 === Reference implementations ===
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8 * Fortran 2003 version ([[HG1G2tools module>>attach:HG1G2tools.f]] and [[Example fit>>attach:example_fit.f]], or [[zip file>>attach:HG1G2tools-Fortran.zip]] for codes, readme and example data.) (//version at 2013-08-29//)
9 * Mathematica version ([[HG1G2tools package>>attach:HG1G2tools.m]] and [[Example fit>>attach:Example fit.nb]]) (//version at 2013-08-29//)
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11 === Other tools ===
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13 * [[Online implementation>>url:https://psr.it.helsinki.fi/HG1G2/||shape="rect"]] of the //H//,//G//,,1,,,//G//,,2,, system in flux space (2015) with automatic model selection
14 * For Python, we recommend the Python-package [[sbpy>>url:https://sbpy.org||shape="rect"]], an Astropy affiliated package for asteroid and comet researchers. It has the //H//,//G//,,1,,,//G//,,2,, and //H//,//G//,,12,, photometric systems implemented. An example how to fit observations using sbpy is here ([[Python Jupyter notebook>>attach:Fitting HG1G2 with constrains using Python and sbpy.ipynb]] or [[PDF>>attach:Fitting HG1G2 with constrains using Python and sbpy.pdf]]), using //scipy.optimize// function //minimize//.
15 * [[Example data from (44) Nysa>>attach:44_Nysa.dat]]
16 * Original [[Fortran 77 version>>attach:original_hg1g2_f77.zip]]
17 * (D(% style="color: rgb(17,17,17);" %)eprecated(%%)) Python version ([[HG1G2tools package>>attach:HG1G2tools-Python-master.zip]]) (//version at 2016-04-20//)
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19 === Contribute ===
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21 You are more than welcome to contribute. If you are interested in creating a reference implementation using some language or platform that is currently lacking an implementation, please read [[guide for developers>>attach:guide_for_developer.pdf]] and send your source code here for distribution. All other tools that are somehow related to //H//,//G//,,1,,,//G//,,2,, system are also welcomed!
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23 You can contact [[Antti.I.Penttila( a t )helsinki.fi>>mailto:antti.i.penttilaAThelsinki.fi||shape="rect"]] for more information.
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25 === References ===
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29 {{id name="ref"/}}
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31 Reference to this page: A. Penttilä, Collection of tools for //H//,//G//,,1,,,//G//,,2,, system, [[http:~~/~~/wiki.helsinki.fi/display/PSR/HG1G2+tools>>url:http://wiki.helsinki.fi/display/PSR/HG1G2+tools||rel="nofollow" shape="rect" class="external-link"]] (2012).
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33 Reference to IAU-adopted version: K. Muinonen, I.N. Belskaya, A. Cellino, M. Delbò, A.-C. Levasseur-Regourd, A. Penttilä, E.F. Tedesco (2010). A three-parameter magnitude phase function for asteroids, //Icarus// **209**(2), 542-555. [[DOI:10.1016/j.icarus.2010.04.003>>url:http://dx.doi.org/10.1016/j.icarus.2010.04.003||shape="rect"]] ([[local copy>>attach:Muinonen-2010-Icarus.pdf]])
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35 Reference to 2015 flux space extension and online implementation: A. Penttilä, V.G. Shevchenko, O. Wilkman, K. Muinonen (2016). //H//,//G//,,1,,,//G//,,2,, photometric phase function extended to low-accuracy data, //Planetary and Space Science// **123**, 117-125, [[DOI:10.1016/j.pss.2015.08.010>>url:http://dx.doi.org/10.1016/j.pss.2015.08.010||shape="rect"]] ([[local copy>>attach:PSS-vol123-2016-Penttilä.pdf]])
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