Aims. The EROS-2 project was designed to test the hypothesis that massive compact halo objects (the so-called "machos") could be a major component of the dark matter halo of the Milky Way galaxy. To this end, EROS-2 monitored over 6.7 years 33 × 10 6 stars in the Magellanic clouds for microlensing events caused by such objects. Methods. In this work, we use only a subsample of 7 × 10 6 bright stars spread over 84 deg 2 of the LMC and 9 deg 2 of the SMC. The strategy of using only bright stars helps to discriminate against background events due to variable stars and allows a simple determination of the effects of source confusion (blending). The use of a large solid angle makes the survey relatively insensitive to effects that could make the optical depth strongly direction dependent. Results. Using this sample of bright stars, only one candidate event was found, whereas ∼39 events would have been expected if the Halo were entirely populated by objects of mass M ∼ 0.4 M . Combined with the results of EROS-1, this implies that the optical depth toward the Large Magellanic Cloud (LMC) due to such lenses is τ < 0.36 × 10 −7 (95% CL), corresponding to a fraction of the halo mass of less than 8%. This optical depth is considerably less than that measured by the MACHO collaboration in the central region of the LMC. More generally, machos in the mass range 0.6 × 10 −7 M < M < 15 M are ruled out as the primary occupants of the Milky Way Halo.

and is difficult to explain with models that assume local thermodynamic equilibrium

Aims. We present a new EROS-2 measurement of the microlensing optical depth toward the Galactic Bulge. Methods. Light curves of 5.6×10 6 clump-giant stars distributed over 66 deg 2 of the Bulge were monitored during seven Bulge seasons. 120 events were found with apparent amplifications greater than 1.6 and Einstein radius crossing times in the range 5 d < t E < 400 d. This is the largest existing sample of clump-giant events and the first to include northern Galactic fields. Results. In the Galactic latitude range 1.4• < |b| < 7.0 • , we find τ/10 −6 = (1.62 ± 0.23) exp [−a(|b| − 3 deg)] with a = (0.43 ± 0.16) deg −1 . These results are in good agreement with our previous measurement, with recent measurements of the MACHO and OGLE-II groups, and with predictions of Bulge models.

We attempt to identify all microlensing parallax events for which the parallax fit improves \Delta\chi^2 > 100 relative to a standard microlensing model. We outline a procedure to identify three types of discrete degeneracies (including a new one that we dub the ``ecliptic degeneracy'') and find many new degenerate solutions in 16 previously published and 6 unpublished events. Only four events have one unique solution and the other 18 events have a total of 44 solutions. Our sample includes three previously identified black-hole (BH) candidates. We consider the newly discovered degenerate solutions and determine the relative likelihood that each of these is a BH. We find the lens of event MACHO-99-BLG-22 is a strong BH candidate (78%), event MACHO-96-BLG-5 is a marginal BH candidate (37%), and MACHO-98-BLG-6 is a weak BH candidate (2.2%). The lens of event OGLE-2003-BLG-84 may be a Jupiter-mass free-floating planet candidate based on a weak 3 sigma detection of finite-source effects. We find that event MACHO-179-A is a brown dwarf candidate within ~100 pc of the Sun, mostly due to its very small projected Einstein radius, \tilde r_E = 0.23+-0.05 AU. As expected, these microlensing parallax events are biased toward lenses that are heavier and closer than average. These events were examined for xallarap (or binary-source motion), which can mimic parallax. We find that 23% of these events are strongly affected by xallarap.Comment: 69 Pages, 10 Figures, 24 Tables, Submitted to Ap

We present a database (LOGPHOT) of stellar photometry of Local Group galaxies obtained with the Hubble Space Telescope using the Wide Field Planetary Camera 2 (WFPC2). The database includes photometry from all WFPC2 observations taken through 2003 with long exposures (>500 s) in F555W and F814W, and many observations in which long exposures were taken in at least two broadband filters. We have attempted to derive and use techniques that produce the best photometry; the database has been fully populated using the HSTphot photometry package. To test the effects of different techniques, independent reductions were made for a few fields, and the comparison of these highlights some important issues and gives an estimate of plausible errors; these tests also led to some minor modifications and improvements to HSTphot. We provide both point-spread function photometry and subtracted-frame aperture photometry and discuss the merits of each. The database is available electronically. In addition to discussing the techniques used to construct the database, we present color-magnitude diagrams from single fields in each of the Local Group galaxies that have been observed; these provide an educational and visual display of the variety of star formation histories observed in Local Group galaxies.

HATSouth is the world's first network of automated and homogeneous telescopes that is capable of year-round 24-hour monitoring of positions over an entire hemisphere of the sky. The primary scientific goal of the network is to discover and characterize a large number of transiting extrasolar planets, reaching out to long periods and down to small planetary radii. HATSouth achieves this by monitoring extended areas on the sky, deriving high precision light curves for a large number of stars, searching for the signature of planetary transits, and confirming planetary candidates with larger telescopes. HATSouth employs six telescope units spread over three prime locations with large longitude separation in the southern hemisphere (Las Campanas Observatory, Chile; HESS site, Namibia; Siding Spring Observatory, Australia). Each of the HATSouth units holds four 0.18 m diameter f/2.8 focal ratio telescope tubes on a common mount producing an 8.2 • × 8.2 • field-of-view on the sky, imaged using four 4K × 4K CCD cameras and Sloan r filters, to give a pixel scale of 3.7 ′′ pixel −1 . The HATSouth network is capable of continuously monitoring 128 square arc-degrees at celestial positions moderately close to the anti-solar direction. We present the technical details of the network, summarize operations, and present detailed weather statistics for the three sites. Robust operations have meant that on average each of the six HATSouth units has conducted observations on ∼ 500 nights over a two-year time period, yielding a total of more than 1 million science frames at four minute integration time, and observing ∼ 10.65 hours per day on average. We describe the scheme of our data transfer and reduction from raw pixel images to trend-filtered light curves and transiting planet candidates. Photometric precision reaches ∼ 6 mmag at 4 minute cadence for the brightest non-saturated stars at r ≈ 10.5. We present detailed transit recovery simulations to determine the expected yield of transiting planets from HATSouth. We highlight the advantages of networked operations, namely, a threefold increase in the expected number of detected planets, as compared to all telescopes operating from the same site.

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Abstract. We present a measurement of the microlensing optical depth toward the Galactic bulge based on the analysis of 15 contiguous 1 deg 2 fields centered on (l = 2.• 5, b = −4.• 0) and containing N * = 1.42 × 10 6 clump-giant stars (belonging to the extended clump area) monitored during almost three bulge seasons by EROS (Expérience de Recherche d'Objets Sombres). We find τ bulge = 0.94 ± 0.29 × 10 −6 averaged over all fields, based on 16 microlensing events with clump giants as sources. This value is substantially below several other determinations by the MACHO and OGLE groups and is more in agreement with what is expected from axisymmetric and non-axisymmetric bulge models.