Photoelectric B and V photometry of RR Lyrae was obtained over a 77 day interval in 1996. In addition to the 0.5668 day primary period, RR Lyr displayed a prominent 40 day Blazhko cycle during this time span. The observed light curve can be well but not perfectly described by frequency triplets of the form kf ϩ 0 , where , 1, 2, …, , 0, 1, is the primary pulsation frequency, and is the Blazhko frequency.

International audienceWe investigate the nature of defects triggering laser damage in fused silica in subsurface fracturesin nanosecond near ultraviolet regime. Mechanical, laser induced surface flaws as well as pristinesilica surface were characterized by optical microscopy and luminescence confocal microscopybefore and after acid etching. In all cases, photoluminescence decreases with etching timeassessing the existence of defects close to the surface. Spectral analysis of the evolution of thesesignals during etching allows new interpretations of the nature of precursors inducing damage.Green luminescence around 2.25 eV is seen as a potential subsurface fracture indicator leading tolaser damage

International audienceIn this paper, we report the results of photo-luminescence experiments on high purity silica glass. Two different types of defects located on optical pieces are investigated: indented sites and laser damage craters. Visible luminescence excited at the wavelength of 325 nm (3.81 eV) is observed using confocal microscopy. Each type of defect produces qualitatively different luminescence spectra. In the case of indented sites, the well known Oxygen Deficient Center (ODC) band peaking at 2.75 eV is clearly observed, while for laser damage areas, another classical luminescent object is found: the Non Bridging Oxygen Hole Center (NBOHC) which peaks at 1.9 eV. On both types of defects, the luminescence spectra yield a strong peak around 2.2 eV but its interpretation is still controversory