tokens: as follows. The observations are described in Sect. 2. Sections 3 and 4 give reduction techniques and results of analysis of the obtained spectroscopic and photometric data. Discussion on the derived results can be found in Sect. 4. Brief conclusions are presented in Sect. 5. 2. Observations 2.1. Photometry December, 2006. Spectrophotometric observations were carried out on December 12, 2006 with the multi-mode focal reducer SCORPIO attached to the prime focus of the 6 m Big Telescope Alt-azimuth (BTA) operated by Special Astrophysical Observatory (SAO) of the Russian Academy of Sciences (Russia). The focal reducer provided both photometric mode and long-slit spectroscopic mode ( Afanasiev Moiseev 2005 ). A CCD chip EEV-42-40 of pixels was used as a detector. The focal reducer converts the focal ratio to /2.6, providing a pixel scale of 018 per pixel and field of view of . To increase the signal-to-noise ratio (S/N) of measured signal, on-chip binning of 2 in the spatial direction was applied. s image of the comet was obtained through a broadband filter (center wavelength nm, full width at half maximum ( FWHM ) nm); s images were taken through a broadband Rc filter ( nm, nm). A field of standard stars (PG 0231) was observed at approximately the same airmasses as the comet to perform the photometric calibration ( Landolt 1992 ). Reference zero points and color terms for transformation to the standard photometric system were calculated using the standard stars with a scatter of less than 0.03 mag on average. The difference between the comet and standard field airmasses was considered to be small and was compensated for with the mean monochromatic extinction coefficients measured for Peak Terskol Observatory, which is located in the same mountain region ( Kulyk et al. 2004 ). The twilight sky was observed through the filters used to construct flat field images. November, 2007. Another data set was obtained on November 9, 2007 with the 6 m Telescope. The observation set-up was similar to that described in the previous paragraph. s images were acquired with a broadband filter ( nm, nm). The spectrophotometric standard star Feige 34 was observed at the similar airmasses as the comet airmasses to carry out absolute photometric calibration ( Oke 1990 ). We used the mean monochromatic coefficient to compensate the first order of extinction, neglecting the color member, which is small in the -band and comparable to the uncertainty of the main extinction itself. A set of exposures from the evening and morning twilight sky was obtained to create a flat field image. October, 2008. To collect images of the comet, we used the 2 m RCC Telescope at Peak Terskol Observatory operated by the International Center for Astronomical, Medical and Ecological Research (IC AMER, Terskol, Kabardino-Balkaria, Russia). A focal reducer mounted at the prime focus converted the initial focal ratio of to , providing an image scale of 099 per pixel and useful field of view of 94.
ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Instrument O O O O O O O B-Telescope I-Telescope I-Telescope I-Telescope I-Telescope B-Telescope O O B-Observatory I-Observatory I-Observatory B-Observatory O O B-Organization I-Organization I-Organization I-Organization B-Location O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O B-Instrument O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O O B-CelestialRegion I-CelestialRegion O O O O O O O O O O O O O O O O B-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Observatory I-Observatory I-Observatory O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope I-Telescope I-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O B-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope I-Telescope I-Telescope I-Telescope O B-Observatory I-Observatory I-Observatory O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization B-Location I-Location I-Location O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O