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Astron. Astrophys. 342, L45-L48 (1999)

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2. Optical observations

On August 1-5, 1997, we obtained R and I CCD photometry with the IGI focal reducer at the 2.1m telescope at McDonald Observatory. Using a f/1.96 135 mm camera lens and a [FORMULA] TK4 CCD with [FORMULA] pixels, the measured scale was [FORMULA]/pixel and the field of view almost [FORMULA]. Conditions ranged from photometric to very poor, with a seeing of [FORMULA]. We obtained 41 R images and 40 I images, most of them with exposures of 6 min and most of the images taken in the first 3 nights when conditions were best. Relative fluxes of all stars near the nova position were obtained by measuring intensities within [FORMULA] circular apertures centered on the star. Typical errors in the derived differential magnitudes were 0.05 mag in R and 0.1 mag in I for a 21 mag star. Magnitudes in the Johnson-Kron-Cousins photometric system were estimated by comparison with images of Landolt fields (Landolt 1992) taken during the photometric night.

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© European Southern Observatory (ESO) 1999

Online publication: February 23, 1999