We describe the public ESO near-IR variability survey (VVV) scanning the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high. The survey will take 1929 h of observations with the 4-m VISTA telescope during 5 years (2010-2014), covering ˜109 point sources across an area of 520 deg2, including 33 known globular clusters and ˜350 open clusters. The final product will be a deep near-IR atlas in five passbands (0.9-2.5 μm) and a catalogue of more than 106 variable point sources. Unlike single-epoch surveys that, in most cases, only produce 2-D maps, the VVV variable star survey will enable the construction of a 3-D map of the surveyed region using well-understood distance indicators such as RR Lyrae stars, and Cepheids. It will yield important information on the ages of the populations. The observations will be combined with data from MACHO, OGLE, EROS, VST, Spitzer, HST, Chandra, INTEGRAL, WISE, Fermi LAT, XMM-Newton, GAIA and ALMA for a complete understanding of the variable sources in the inner Milky Way. This public survey will provide data available to the whole community and therefore will enable further studies of the history of the Milky Way, its globular cluster evolution, and the population census of the Galactic Bulge and center, as well as the investigations of the star forming regions in the disk. The combined variable star catalogues will have important implications for theoretical investigations of pulsation properties of stars

We present constraints on the dark energy equation-of-state parameter, w ¼ P/( c 2 ), using 60 SNe Ia from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat universe. By including constraints on ( M , w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w ¼ À1:05 þ0:13 À0:12 (stat 1 ) AE 0:13 (sys) and M ¼ 0:274 þ0:033 À0:020 (stat 1 ) with a bestfit 2 /dof of 0.96. These results are consistent with those reported by the Supernova Legacy Survey from the first year of a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the first-results Supernova Legacy Survey SNe Ia, we obtain a joint constraint of w ¼ À1:07 þ0:09 À0:09 (stat 1 ) AE 0:13 (sys), M ¼ 0:267 þ0:028 À0:018 (stat 1 ) with a best-fit 2 /dof of 0.91. The current global SN Ia data alone rule out empty ( M ¼ 0), matter-only M ¼ 0:3, and M ¼ 1 universes at >4.5 . The current SN Ia data are fully consistent with a cosmological constant.

We report the results of a 3 year-long dedicated monitoring campaign of a restless Luminous Blue Variable (LBV) in NGC 7259. The object, named SN 2009ip, was observed photometrically and spectroscopically in the optical and near-infrared domains. We monitored a number of erupting episodes in the past few years, and increased the density of our observations during eruptive episodes. In this paper we present the full historical data set from 2009-2012 with multi-wavelength dense coverage of the two high luminosity events between August -September 2012. We construct bolometric light curves and measure the total luminosities of these eruptive or explosive events. We label them the 2012a event (lasting ∼ 50 days) with a peak of 3 × 10 41 ergs −1 , and the 2012b event (14 day rise time, still ongoing) with a peak of 8 × 10 42 ergs −1 . The latter event reached an absolute Rband magnitude of about -18, comparable to that of a core-collapse supernova (SN). Our historical monitoring has detected high-velocity spectral features (∼13000 km s −1 ) in September 2011, one year before the current SN-like event. This implies that the detection of such high velocity outflows cannot, conclusively, point to a core-collapse SN origin. We suggest that the initial peak in the 2012a event was unlikely to be due to a faint core-collapse SN. We propose that the high intrinsic luminosity of the latest peak, the variability history of SN 2009ip, and the detection of broad spectral lines indicative of high-velocity ejecta are consistent with a pulsational pair-instability event, and that the star may have survived the last outburst. The question of the survival of the LBV progenitor star and its future fate remain open issues, only to be answered with future monitoring of this historically unique explosion.

Optical and near‐infrared (near‐IR) observations of the Type Ic supernova (SN Ic) 2004aw are presented, obtained from −3 to +413 d with respect to the B‐band maximum. The photometric evolution is characterized by a comparatively slow post‐maximum decline of the light curves. The peaks in redder bands are significantly delayed relative to the bluer bands, the I‐band maximum occurring 8.4 d later than that in B. With an absolute peak magnitude of −18.02 in the V band the SN can be considered fairly bright, but not exceptional. This also holds for the U through I bolometric light curve, where SN 2004aw has a position intermediate between SNe 2002ap and 1998bw. Spectroscopically SN 2004aw provides a link between a normal SN Ic like SN 1994I and the group of broad‐lined SNe Ic. The spectral evolution is rather slow, with a spectrum at day +64 being still predominantly photospheric. The shape of the nebular [O i]λλ6300, 6364 line indicates a highly aspherical explosion. Helium cannot be unambiguously identified in the spectra, even in the near‐IR. Using an analytical description of the light‐curve peak we find that the total mass of the ejecta in SN 2004aw is 3.5–8.0 M⊙, significantly larger than that in SN 1994I, although not as large as in SN 1998bw. The same model suggests that about 0.3 M⊙ of 56Ni has been synthesized in the explosion. No connection to a GRB can be firmly established.

Aims. We present a study of the optical and near-infrared (NIR) properties of the Type Ia Supernova (SN Ia) 2003du.Methods. An extensive set of optical and NIR photometry and low-resolution long-slit spectra was obtained using a number of facilities. The observations started 13 days before B-band maximum light and continued for 480 days with exceptionally good time sampling. The optical photometry was calibrated through the S-correction technique. Results. The UBVRIJHK light curves and the color indices of SN 2003du closely resemble those of normal SNe Ia. SN 2003du reached a B-band maximum of 13.49 ± 0.02 mag on JD2 452 766.38 ± 0.5. We derive a B-band stretch parameter of 0.988 ± 0.003, which corresponds to ∆m 15 = 1.02 ±0.05, indicative of a SN Ia of standard luminosity. The reddening in the host galaxy was estimated by three methods, and was consistently found to be negligible. Using an updated calibration of the V and JHK absolute magnitudes of SNe Ia, we find a distance modulus µ = 32.79 ± 0.15 mag to the host galaxy, UGC 9391. We measure a peak uvoir bolometric luminosity of 1.35(±0.20) × 10 43 erg s −1 and Arnett's rule implies that M56 Ni 0.68 ± 0.14 M of 56 Ni was synthesized during the explosion. Modeling of the uvoir bolometric light curve also indicates M56 Ni in the range 0.6−0.8 M . The spectral evolution of SN 2003du at both optical and NIR wavelengths also closely resembles normal SNe Ia. In particular, the Si ii ratio at maximum R(Si ii) = 0.22 ± 0.02 and the time evolution of the blueshift velocities of the absorption line minima are typical. The pre-maximum spectra of SN 2003du showed conspicuous high-velocity features in the Ca ii H&K doublet and infrared triplet, and possibly in Si ii λ6355, lines. We compare the time evolution of the profiles of these lines with other well-observed SNe Ia and we suggest that the peculiar pre-maximum evolution of Si ii λ6355 line in many SNe Ia is due to the presence of two blended absorption components.