J/A+A/561/A138 Transiting planets search Matlab/Octave source code (Ofir+, 2014)
Optimizing the search for transiting planets in long time series.
Ofir A.
<Astron. Astrophys. 561, A138 (2014)>
=2014A&A...561A.138O 2014A&A...561A.138O
ADC_Keywords: Models ; Planets ; Photometry
Keywords: methods: data analysis - planets and satellites: detection -
stars: planetary systems
Abstract:
Transit surveys, both ground- and space-based, have already
accumulated a large number of light curves that span several years.
The search for transiting planets in these long time series is
computationally intensive. We wish to optimize the search for both
detection and computational efficiencies.
We assume that the searched systems can be described well by Keplerian
orbits. We then propagate the effects of different system parameters
to the detection parameters.
We show that the frequency information content of the light curve is
primarily determined by the duty cycle of the transit signal, and thus
the optimal frequency sampling is found to be cubic and not linear.
Further optimization is achieved by considering duty-cycle dependent
binning of the phased light curve. By using the (standard) BLS, one is
either fairly insensitive to long-period planets or less sensitive to
short-period planets and computationally slower by a significant
factor of ∼330 (for a 3yr long dataset). We also show how the physical
system parameters, such as the host star's size and mass, directly
affect transit detection. This understanding can then be used to
optimize the search for every star individually.
By considering Keplerian dynamics explicitly rather than implicitly
one can optimally search the BLS parameter space. The presented
Optimal BLS enhances the detectability of both very short and very
long period planets, while allowing such searches to be done with much
reduced resources and time.
Description:
The Matlab/Octave source code for Optimal BLS is made available here.
Detailed descriptions of all inputs and outputs are given by comment
lines in the file.
Note: Octave does not currently support parallel for loops ("parfor").
Octave users therefore need to change the "parfor" command (line 217
of OptimalBLS.m) to "for".
Objects:
---------------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------------
19 02 43.06 +50 14 28.7 Kepler-10 = KOI-72 = GSC 3549-354
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File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
Kepler-10.bls.png 512 24 BLS image (Box-fitting Least Squares)
Kepler-10.lc 80 50736 Normalized light curve of the Kepler-10,
ascii format
Kepler-10.lc.mat 512 1919 Normalized light curve of the Kepler-10,
Matlab-format
OptimalBLS.m 265 394 Matlab/Octave source code
TestOptimalBLS.m 86 37 Demonstration of applying Optimal BLS on
the Kepler-10 test data
--------------------------------------------------------------------------------
OptimalBLS.m
------------------------------------------------------------------------------
Name of subroutine Description
------------------------------------------------------------------------------
Main : Calculates BLS in an optimal grid for several stars.
returns just the frequency information (BLS priodogram)
for each star.
OneFreq : Provides additional description on the best-fitting signal
for a given star and given frequency.
------------------------------------------------------------------------------
TestOptimalBLS.m
------------------------------------------------------------------------------
Name of subroutine Description
------------------------------------------------------------------------------
Main : Calculates BLS on Kepler-10 as test data
Note BaseDir needs to be the location of this package.
load the correct file (Kepler-10.lc.mat - or -
Kepler-10.lc, for matlab or octave, respectively)
Simply run it as-as:
Matlab: ≫ TestOptimalBLS
- or -
Octave: octave:1> TestOptimalBLS
------------------------------------------------------------------------------
Acknowledgements:
For any questions, comments and bug reports - please write to:
Aviv Ofir, avivofir(at)astro.physik.uni-goettingen.de
History:
* 24-Jan-2014: on-line version
* 26-Jan-2015: file OptimalBLS.m corrected (from author)
(End) Patricia Vannier [CDS] 10-Jan-2014