Limits on Stellar and Planetary Companions in Microlensing Event OGLE‐1998‐BUL‐14

Abstract

We present the PLANET photometric data set for OGLE-1998-BUL-14, a high-magnification (Amax~16) event alerted by the OGLE collaboration toward the Galactic bulge in 1998. The PLANET data set consists a total of 461 I-band and 139 V-band points, the majority of which was taken over a 3 month period. The median sampling interval during this period is about 1 hr, and the 1 σ scatter over the peak of the event is 1.5%. The excellent data quality and high maximum magnification of this event make it a prime candidate to search for the short-duration, low-amplitude perturbations that are signatures of a planetary companion orbiting the primary lens. The observed light curve for OGLE-1998-BUL-14 is consistent with a single lens (no companion) within photometric uncertainties. We calculate the detection efficiency of the light curve to lensing companions as a function of the mass ratio and angular separation of the two components. We find that companions of mass ratio >=0.01 are ruled out at the 95% significance level for projected separations between 0.4 and 2.4rE, where rE is the Einstein ring radius of the primary lens. Assuming that the primary is a G dwarf with rE~3 AU, our detection efficiency for this event is ~60% for a companion with the mass and separation of Jupiter and ~5% for a companion with the mass and separation of Saturn. Our efficiencies for planets like those around υ And and 14 Her are >75%.