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Item Finding Ultracool Brown Dwarfs With MegaCam On CFHT: Method And First Results(2008-06) Delorme, P.; Willott, C. J.; Forveille, T.; Delfosse, X.; Reyle, C.; Bertin, E.; Albert, L.; Artigau, E.; Robin, A. C.; Allard, F.; Doyon, R.; Hill, G. J.; Hill, G. J.Aims. We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to find ultracool brown dwarfs and to constrain the field-brown dwarf mass function thanks to a larger sample of L and T dwarfs. Methods. We identify candidates in CFHT/MegaCam i' and z' images using optimised psf-fitting within Source Extractor, and follow them up with pointed near-infrared imaging on several telescopes. Results. We have so far analysed over 350 square degrees and found 770 brown dwarf candidates brighter than z'(AB) = 22.5. We currently have J-band photometry for 220 of these candidates, which confirms 37% as potential L or T dwarfs. Some are among the reddest and farthest brown dwarfs currently known, including an independent identification of the recently published ULAS J003402.77-005206.7 and the discovery of a second brown dwarf later than T8, CFBDS J005910.83-011401.3. Infrared spectra of three T dwarf candidates confirm their nature, and validate the selection process. Conclusions. The completed survey will discover similar to 100 T dwarfs and similar to 500 L dwarfs or M dwarfs later than M8, approximately doubling the number of currently known brown dwarfs. The resulting sample will have a very well-defined selection function, and will therefore produce a very clean luminosity function.Item Spectropolarimetry Of The Type IIb Supernova 2001Ig(1)(2007-12) Maund, Justyn R.; Wheeler, J. Craig; Patat, Ferdinando; Wang, Lifan; Baade, Dietrich; Hoflich, Peter A.; Maund, Justyn R., J. Craig Wheeler, Ferdinando Patat, Lifan Wang, Dietrich Baade, and A. H. Peter. "Spectropolarimetry of the Type IIb Supernova 2001ig." The Astrophysical Journal, Vol. 671, No. 2 (Dec., 2007): 1944.We present spectropolarimetric observations of the Type IIb SN 2001ig in NGC 7424; conducted with the ESO VLT FORS1 on 2001 December 16, 2002 January 3, and 2002 August 16, or 13, 31, and 256 days postexplosion. These observations are at three different stages of the SN evolution: (1) the hydrogen-rich photospheric phase, (2) the Type II to Type Ib transitional phase, and (3) the nebular phase. At each of these stages, the observations show remarkably different polarization properties as a function of wavelength. We show that the degree of interstellar polarization is 0.17%. The low intrinsic polarization (similar to 0.2%) at the first epoch is consistent with an almost spherical (<10% deviation from spherical symmetry) hydrogen-dominated ejecta. Similar to SN 1987A and to Type IIP SNe, a sharp increase in the degree of the polarization (similar to 1%) is observed when the outer hydrogen layer becomes optically thin by day 31; only at this epoch is the polarization well described by a "dominant axis.'' The polarization angle of the data shows a rotation through similar to 40 degrees between the first and second epochs, indicating that the asymmetries of the first epoch were not directly coupled with those observed at the second epoch. For the most polarized lines, we observe wavelength-dependent loop structures in addition to the dominant axis on the Q-U plane. We show that the polarization properties of Type IIb SNe are roughly similar to one another, but with significant differences arising due to line blending effects especially with the high velocities observed for SN 2001ig. This suggests that the geometry of SN 2001ig is related to SN 1993J and that these events may have arisen from a similar binary progenitor system.