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Register a new userWeCAPP - The Wendelstein Calar Alto Pixellensing Project I Tracing Dark and Bright Matter in M31
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We present WeCAPP, a long term monitoring project searching for microlensing events towards M 31. Since 1997 the bulge of M 31 was monitored in two different wavebands with the Wendelstein 0.8 m telescope. In 1999 we extended our observations to the Calar Alto 1.23 m telescope. Observing simultaneously at these two sites we obtained a time coverage of 53 % during the observability of M 31. To check thousands of frames for variability of unresolved sources, we used the optimal image subtraction method (OIS) by Alard & Lupton (1998) This enabled us to minimize the residuals in the difference image analysis (DIA) and to detect variable sources with amplitudes at the photon noise level. Thus we can detect microlensing events with corresponding amplifications A > 10 of red clump giants with M_I = 0.
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We present light curves from the novae detected in the long-term, M31 monitoring WeCAPP project. The goal of WeCAPP is to constrain the compact dark matter fraction of the M31 halo with microlensing observations. As a by product we have detected 91 novae benefiting from the high cadence and highly sensitive difference imaging technique required for pixellensing. We thus can now present the largest CCD and optical filters based nova light curve sample up-to-date towards M31. We also obtained thorough coverage of the light curve before and after the eruption thanks to the long-term monitoring. We apply the nova taxonomy proposed by Strope et al. (2010) to our nova candidates and found 29 S-class novae, 10 C-class novae, 2 O-class novae and 1 J-class nova. We have investigated the universal decline law advocated by Hachichu and Kato (2006) on the S-class novae. In addition, we correlated our catalogue with the literature and found 4 potential recurrent novae. Part of our catalogue has been used to search for optical counter-parts of the super soft X-ray sources detected in M31 (Pietsch et al. 2005). Optical surveys like WeCAPP, and coordinated with multi-wavelength observation, will continue to shed light on the underlying physical mechanism of novae in the future.
We report the detection of the first 2 microlensing candidates from the Wendelstein Calar Alto Pixellensing Project (WeCAPP). Both are detected with a high signal-to-noise-ratio and were filtered out from 4.5 mill. pixel light curves using a variety of selection criteria. Here we only consider well-sampled events with timescales of 1 d < t_fwhm < 20 d, high amplitude, and low chi^2 of the microlensing fit. The two-color photometry (R,I) shows that the events are achromatic and that giant stars with colors of (R-I) ~ 1.1 mag in the bulge of M31 have been lensed. The magnification factors are 64 and 10 which are obtained for typical giant luminosities of M_I = -2.5 mag. Both lensing events lasted for only a few days (t_fwhm^GL1 = 1.7 d and t_fwhm^GL2 = 5.4 d). The event GL1 is likely identical with PA-00-S3 reported by the POINT-AGAPE project. Our calculations favor in both cases the possibility that MACHOs in the halo of M31 caused the lensing events. The most probable masses, 0.08 M_sun for GL1 and 0.02 M_sun for GL2, are in the range of the brown dwarf limit of hydrogen burning. Solar mass objects are a factor of two less likely.
We present the results of the decade-long M31 observation from the Wendelstein Calar Alto Pixellensing Project (WeCAPP). WeCAPP has monitored M31 from 1997 till 2008 in both R- and I-filters, thus provides the longest baseline of all M31 microlensing surveys. The data are analyzed with the difference imaging analysis, which is most suitable to study variability in crowded stellar fields. We extracted light curves based on each pixel, and devised selection criteria that are optimized to identify microlensing events. This leads to 10 new events, and sums up to a total of 12 microlensing events from WeCAPP, for which we derive their timescales, flux excesses, and colors from their light curves. The color of the lensed stars fall between (R-I) = 0.56 to 1.36, with a median of 1.0 mag, in agreement with our expectation that the sources are most likely bright, red stars at post main-sequence stage. The event FWHM timescales range from 0.5 to 14 days, with a median of 3 days, in good agreement with predictions based on the model of Riffeser et al. (2006).
AstraLux is the Lucky Imaging camera for the Calar Alto 2.2-m telescope, based on an electron-multiplying high speed CCD. By selecting only the best 1-10% of several thousand short exposure frames, AstraLux provides nearly diffraction limited imaging capabilities in the SDSS i and z filters over a field of view of 24x24 arcseconds. By choosing commercially available components wherever possible, the instrument could be built in short time and at comparably low cost. We present the instrument design, the data reduction pipeline, and summarise the performance and characteristics
We present here the Calar Alto Legacy Integral Field Area (CALIFA) survey, which has been designed to provide a first step in this direction.We summarize the survey goals and design, including sample selection and observational strategy.We also showcase the data taken during the first observing runs (June/July 2010) and outline the reduction pipeline, quality control schemes and general characteristics of the reduced data. This survey is obtaining spatially resolved spectroscopic information of a diameter selected sample of $sim600$ galaxies in the Local Universe (0.005< z <0.03). CALIFA has been designed to allow the building of two-dimensional maps of the following quantities: (a) stellar populations: ages and metallicities; (b) ionized gas: distribution, excitation mechanism and chemical abundances; and (c) kinematic properties: both from stellar and ionized gas components. CALIFA uses the PPAK Integral Field Unit (IFU), with a hexagonal field-of-view of $sim1.3sqarcmin$, with a 100% covering factor by adopting a three-pointing dithering scheme. The optical wavelength range is covered from 3700 to 7000 {AA}, using two overlapping setups (V500 and V1200), with different resolutions: Rsim850 and Rsim1650, respectively. CALIFA is a legacy survey, intended for the community. The reduced data will be released, once the quality has been guaranteed. The analyzed data fulfill the expectations of the original observing proposal, on the basis of a set of quality checks and exploratory analysis. We conclude from this first look at the data that CALIFA will be an important resource for archaeological studies of galaxies in the Local Universe.
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