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Date: Wed, 7 Apr 93 19:05:25 GMT From: gav@astro.as.utexas.edu (Gerard de Vaucouleurs) Subject: SN1993J, V light curve from visual and CCD observations Could you please circulate this cry for help. There is too much disagreement between the CCD and visual observations, near and immediately past maximum. Thanks. GV(gav@astro.as.utexas.edu) V-BAND LIGHT CURVE: the V (CCD) and mv (visual) observations, all reduced as far as possible to the same zero point (*B = 11.90), give different epochs for maximum light. Polynomial fits (4 terms) give the following epochs and magnitude at maximum: ____________________________________________________________________ Data n JD-2449000 Maximum V(max) rms residual V (CCD) 22 077 to 083 076.0 10.6 0.04 mag mv 62 075 to 083 077.7 10.5 0.21 ____________________________________________________________________ The two curves agree near JD 077 and JD 083, but diverge by up to 0.5 mag near JD 079-080. The V(CCD) curve is inconsistent with the early visual observations (mv = 11 12, JD 075-077). Could the visual observers please identify their comparison stars and adopted magnitudes? If the maximum did in fact take place on March 29-30 as suggested by the CCD data, the rise from onset (JD 072.0?) would be incredibly fast. The visual data fit in much more smoothly with the discovery and pre-discovery data. Has anyone done bona fide UBVRI photometry of the supernova and comparison stars with a real photoelectric photometer with a 1P21 or S20 cathode? G. de Vaucouleurs (gav@astro.as.utexas.edu)
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