Letter to the Editor An ongoing parallax microlensing event OGLE-1999-CAR-1 toward Carina

We study the first microlensing event toward the Carina spiral arm discovered by the OGLE collaboration. We demonstrate that this long duration event exhibits strong parallax signatures. Additional information from the parallax effect allows us to determine the lens transverse velocity projected onto the Sun-source line to be ∼ 145 km s−1. We also estimate the optical depth, event rate and duration distribution for microlensing toward Carina. We show that this event is broadly consistent with these predictions.