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 TK4 CCD with pixels, the measured scale was /pixel and the field of view almost . Conditions ranged from photometric to very poor, with a seeing of . 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 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.
© European Southern Observatory (ESO) 1999
Online publication: February 23, 1999