Table 3. Open in new tab Successive...

Model	Single	Single, parallax	Single, parallax	Binary, parallax	Binary, parallax
t₀	6931.685 ± 0.005	6931.39 ± 0.09	6931.359 ± 0.006	6931.429 ± 0.003	6931.477 ± 0.003
t_E [d]	179.13 ± 0.39	300 ± 20	287 ± 16	286 ± 18	279 ± 7
u₀	0.009275 ± 0.000011	−0.0052 ± 0.0018	−0.0065 ± 0.0004	−0.0067 ± 0.0004	−0.0067 ± 0.0002
\|$\pi$\|_{E, N}	–	−0.367 ± 0.012	−0.354 ± 0.009	−0.364 ± 0.009	−0.353 ± 0.007
\|$\pi$\|_{E, E}	–	−0.143 ± 0.015	−0.178 ± 0.008	−0.171 ± 0.009	−0.171 ± 0.006
d	–	–	–	0.713 ± 0.006	1.428 ± 0.009
q	–	–	–	(3.6 ± 0.3) × 10⁻⁴	(3.8 ± 0.2) × 10⁻⁴
α	–	–	–	4.023 ± 0.002	4.022 ± 0.002

Model

Single

Single, parallax

Binary, parallax

Data selection

Off-peak

All

Data sets

OGLE (I)

All except Dk1.54m

All

Data scaling

None

u₀ < 0 off-peak

Minimisation

ML robust rescale

ML robust

Option

–

u₀ < 0

u₀ < 0, close

u₀ < 0, wide

t₀

6931.685 ± 0.005

6931.39 ± 0.09

6931.359 ± 0.006

6931.429 ± 0.003

6931.477 ± 0.003

t_E [d]

179.13 ± 0.39

300 ± 20

287 ± 16

286 ± 18

279 ± 7

u₀

0.009275 ± 0.000011

−0.0052 ± 0.0018

−0.0065 ± 0.0004

−0.0067 ± 0.0004

−0.0067 ± 0.0002

|$\pi$|_{E, N}

–

−0.367 ± 0.012

−0.354 ± 0.009

−0.364 ± 0.009

−0.353 ± 0.007

|$\pi$|_{E, E}

–

−0.143 ± 0.015

−0.178 ± 0.008

−0.171 ± 0.009

−0.171 ± 0.006

–

0.713 ± 0.006

1.428 ± 0.009

–

(3.6 ± 0.3) × 10⁻⁴

(3.8 ± 0.2) × 10⁻⁴

–

4.023 ± 0.002

4.022 ± 0.002

Model	Single	Single, parallax	Single, parallax	Binary, parallax	Binary, parallax
t₀	6931.685 ± 0.005	6931.39 ± 0.09	6931.359 ± 0.006	6931.429 ± 0.003	6931.477 ± 0.003
t_E [d]	179.13 ± 0.39	300 ± 20	287 ± 16	286 ± 18	279 ± 7
u₀	0.009275 ± 0.000011	−0.0052 ± 0.0018	−0.0065 ± 0.0004	−0.0067 ± 0.0004	−0.0067 ± 0.0002
\|$\pi$\|_{E, N}	–	−0.367 ± 0.012	−0.354 ± 0.009	−0.364 ± 0.009	−0.353 ± 0.007
\|$\pi$\|_{E, E}	–	−0.143 ± 0.015	−0.178 ± 0.008	−0.171 ± 0.009	−0.171 ± 0.006
d	–	–	–	0.713 ± 0.006	1.428 ± 0.009
q	–	–	–	(3.6 ± 0.3) × 10⁻⁴	(3.8 ± 0.2) × 10⁻⁴
α	–	–	–	4.023 ± 0.002	4.022 ± 0.002

Table 3.

Open in new tab

Successive construction of models for u₀ < 0 in five steps: (1) rough maximum-likelihood estimation of t₀, t_E, and u₀ from the off-peak OGLE data on the basis of the reported error bars and a single-lens point source model, (2) measurement of parallax parameters from the off-peak OGLE data (assuming u₀ < 0) by means of robust fitting and simultaneous estimation of global systematic error and error bar scaling factor, with refinement of t₀, t_E, and u₀ estimates, (3) confirmation of robustness of parallax measurement and refinement of parameters by including all off-peak data (except for Danish 1.54 m), followed by determination of the systematic error and error bar scaling factor for the Danish 1.54 m data based on the arising model parameters, (4) inclusion of the peak data using the established modification of error bars, and robust fitting of a binary-lens point-source model to all data (including Danish 1.54 m), with seed values for the binary parameters (d, q, α) arising from a grid search with the other parameters fixed, (5) finding a corresponding solution with a wide binary lens (d > 1 rather than d < 1) by using the previously determined parameter values as seed, and just flipping the separation parameter d↔d⁻¹.

Model	Single	Single, parallax	Single, parallax	Binary, parallax	Binary, parallax
Data selection	Off-peak	Off-peak	Off-peak	All	All
Data sets	OGLE (I)	OGLE (I)	All except Dk1.54m	All	All
Data scaling	None	None	None	u₀ < 0 off-peak	u₀ < 0 off-peak
Minimisation	ML	ML robust rescale	ML robust rescale	ML robust	ML robust
Option	–	u₀ < 0	u₀ < 0	u₀ < 0, close	u₀ < 0, wide
t₀	6931.685 ± 0.005	6931.39 ± 0.09	6931.359 ± 0.006	6931.429 ± 0.003	6931.477 ± 0.003
t_E [d]	179.13 ± 0.39	300 ± 20	287 ± 16	286 ± 18	279 ± 7
u₀	0.009275 ± 0.000011	−0.0052 ± 0.0018	−0.0065 ± 0.0004	−0.0067 ± 0.0004	−0.0067 ± 0.0002
\|$\pi$\|_{E, N}	–	−0.367 ± 0.012	−0.354 ± 0.009	−0.364 ± 0.009	−0.353 ± 0.007
\|$\pi$\|_{E, E}	–	−0.143 ± 0.015	−0.178 ± 0.008	−0.171 ± 0.009	−0.171 ± 0.006
d	–	–	–	0.713 ± 0.006	1.428 ± 0.009
q	–	–	–	(3.6 ± 0.3) × 10⁻⁴	(3.8 ± 0.2) × 10⁻⁴
α	–	–	–	4.023 ± 0.002	4.022 ± 0.002

Model	Single	Single, parallax	Single, parallax	Binary, parallax	Binary, parallax
Data selection	Off-peak	Off-peak	Off-peak	All	All
Data sets	OGLE (I)	OGLE (I)	All except Dk1.54m	All	All
Data scaling	None	None	None	u₀ < 0 off-peak	u₀ < 0 off-peak
Minimisation	ML	ML robust rescale	ML robust rescale	ML robust	ML robust
Option	–	u₀ < 0	u₀ < 0	u₀ < 0, close	u₀ < 0, wide
t₀	6931.685 ± 0.005	6931.39 ± 0.09	6931.359 ± 0.006	6931.429 ± 0.003	6931.477 ± 0.003
t_E [d]	179.13 ± 0.39	300 ± 20	287 ± 16	286 ± 18	279 ± 7
u₀	0.009275 ± 0.000011	−0.0052 ± 0.0018	−0.0065 ± 0.0004	−0.0067 ± 0.0004	−0.0067 ± 0.0002
\|$\pi$\|_{E, N}	–	−0.367 ± 0.012	−0.354 ± 0.009	−0.364 ± 0.009	−0.353 ± 0.007
\|$\pi$\|_{E, E}	–	−0.143 ± 0.015	−0.178 ± 0.008	−0.171 ± 0.009	−0.171 ± 0.006
d	–	–	–	0.713 ± 0.006	1.428 ± 0.009
q	–	–	–	(3.6 ± 0.3) × 10⁻⁴	(3.8 ± 0.2) × 10⁻⁴
α	–	–	–	4.023 ± 0.002	4.022 ± 0.002

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