J/MNRAS/343/1131 1998-2000 OGLE events microlensing limits (Tsapras+, 2003)
Microlensing limits on numbers and orbits of extrasolar planets from the
1998-2000 OGLE events.
Tsapras Y., Horne K., Kane S., Carson R.
<Mon. Not. R. Astron. Soc. 343, 1131 (2003)>
=2003MNRAS.343.1131T 2003MNRAS.343.1131T
ADC_Keywords: Planets
Keywords: gravitational lensing - techniques: photometric - planetary systems -
planetary systems: formation
Abstract:
We analyse three years (1998-2000) of Optical Gravitational Lensing
Experiment (OGLE) observations of microlensing events to place limits
on the abundance of planets with a planet-to-star mass ratio q=10-3
at distances ∼1-4AU from their host stars, i.e. 'cool Jupiters'. We
fit a total of 145 events using a maximum-likelihood fit that adjusts
six parameters. Each data point on the light curve allows us to
exclude planets close to the two images of the source appearing on
opposite sides of the Einstein ring of the lens star. We proceed to
compute detection probability maps for each event, using
Δχ2 threshold values of 25, 60 and 100, and combine the
results from all events to place global constraints. Our selection
criteria returned five candidate events for a planet with mass ratio
q=10-3.
Description:
The data sets presented here were obtained from the DoPhot analysis of
the events available at the Optical Gravitational Lensing Experiment
(OGLE) website, ftp://sirius.astrouw.edu.pl/olge . For the purposes of
this analysis, we only considered the events for which the
point-source point-lens (PSPL) model provided adequate fits.
Out of a total of 162 events observed by the OGLE (Udalski,
1994ApJ...436L.103U 1994ApJ...436L.103U) collaboration during a three-year period
(1998-2000), we found that for 145 of these the reduced χ2 of
the PSPL model fit, adjusting six parameters, approached a value of
unity, indicating a good fit.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
position.dat 52 145 All microlensing candidates positions
(from OGLE database)
table1.dat 83 37 Best-fitting parameters for the 1998 OGLE events
table2.dat 83 37 Best-fitting parameters for the 1999 OGLE events
table3.dat 83 71 Best-fitting parameters for the 2000 OGLE events
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See also:
ftp://sirius.astrouw.edu.pl/ogle : OGLE database
J/AcA/51/175 : OGLE-II DIA microlensing events (Wozniak+, 2001)
Byte-by-byte Description of file: position.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- EWS Event designation
13- 20 A8 --- Field OGLE field designation (BUL_SCNN)
22- 27 I6 --- Star Star number
29- 30 I2 h RAh Right ascension (J2000)
32- 33 I2 min RAm Right ascension (J2000)
35- 39 F5.2 s RAs Right ascension (J2000)
41 A1 --- DE- Declination sign (J2000)
42- 43 I2 deg DEd Declination (J2000)
45- 46 I2 arcmin DEm Declination (J2000)
48- 51 F4.1 arcsec DEs Declination (J2000)
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Byte-by-byte Description of file: table?.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- EWS Event designation
13- 23 F11.3 d t0 Time of maximum amplification, in HJD
25- 30 F6.2 d tE Event time-scale (time to cross Einstein ring
diameter)
32- 37 F6.3 mag I0mag Baseline I0 magnitude
39- 44 F6.3 mag A0 Maximum amplification between the projected
position of the source on the lens plane and
the lens itself
46- 48 I3 --- N Number of observations
50- 54 F5.2 --- chi2(4) Reduced χ2 value for four parameters
56- 60 F5.3 mag sigma0 Additive flux error (1)
62- 65 F4.2 --- chi2(5) Reduced χ2 value for five parameters
67- 71 F5.3 --- f Factor f (1)
73- 76 F4.2 --- chi2(6) Reduced χ2 value for six parameters
78- 83 F6.3 --- Dchi2 Average χ2 value
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Note (1): The error bar Si on the flux assumes the form
Si=(sigma02 + f2sigmai2)1/2
where sigma0 is the additive flux error intended to account for the
crowded field effects, sigmai is the original error bar and
f the factor that scale the reported error bars (to take account
of the systematic discrepancy between the fit residuals and the
published error bars)
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History:
From electronic version of the journal
* 21-May-2004: Addition of positions (extracted from the paper)
(End) James Marcout, Patricia Bauer [CDS] 25-Sep-2003