I demonstrate that the two unexpected results in the local universe-(1) anomalous intrinsic (V-I 0 colors of the clump giants and RR Lyrae stars in the Galactic center, and (2) very short distances ...to the Magellanic Clouds (LMC, SMC) as inferred from clump giants-are connected with each other. The (V-I 0 anomaly is partially resolved by using the photometry from phase II of the Optical Gravitational Lensing Experiment (OGLE) rather than phase I. The need for V- or I-magnitude-based change in the bulge (V-I 0 is one option to explain the remaining color discrepancy. Such a change may originate in a coefficient of selective extinction AV E V-I smaller than typically assumed. Application of the (V-I 0 correction (independent of its source) doubles the slope of the absolute magnitude-metallicity relation for clump giants, so that MI RC =-0.23+0.19 Fe/H. Consequently, the estimates of the clump distances to the LMC and SMC are affected. Udalski's distance modulus of µLMC=18.18+/-0.06 increases to 18.27+/-0.07. The distance modulus to the SMC increases by 0.12 to µSMC=18.77+/-0.08. I argue that a more comprehensive assessment of the metallicity effect on MI RC is needed.
We present a catalog of 450 relatively high signal-to-noise ratio microlensing events observed by the MACHO collaboration between 1993 and 1999. The events are distributed throughout our fields, and ...as expected, they show a clear concentration toward the Galactic center. No optical depth is given for this sample, since no blending efficiency calculation has been performed and we find evidence for substantial blending. In a companion paper we give optical depths for the subsample of events on clump giant source stars, where blending is a less significant effect. Several events with sources that may belong to the Sagittarius dwarf galaxy are identified. For these events even relatively low dispersion spectra could suffice to classify these events as either consistent with Sagittarius membership or as non-Sagittarius sources. Several unusual events, such as microlensing of periodic variable source stars, binary lens events, and an event showing extended source effects, are identified. We also identify a number of contaminating background events as cataclysmic variable stars.
We present a ∼5-yr optical light curve of the recurrent Be/X-ray transient A0538-66 obtained as a by-product of the MACHO Project. These data reveal both a long-term modulation at P=420.8±0.8 d and a ...short-term modulation at 16.6510±0.0022 d which, within errors, confirms the previously found orbital period. Furthermore, the orbital activity is only seen at certain phases of the 421-d cycle, suggesting that the long-term modulation is related to variations in the Be star envelope.
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