Photometric study of comets P/Faye 1991 XXI and Zanotta-Brewington 1992 III

We observed comets P/Faye 1991 XXI and Zanotta-Brewington 1992 III from the ESO La Silla Observatory (Chile) with photoelectric photometry and CCD techniques. We used narrow-band filters to calculate the Afϱ parameter and gas production rates for both comets. P/Faye has a low Q(CN)Afϱ of 14 × 1021 molec s−2 cm−1 at perihelion, but a typical reddening between 11 and 15%1000 Å (between 4845 and 6840 Å). Furthermore, CCD imaging revealed a faint and diffuse asymmetry altributed to anisotropic outgassing. As expected for a newly injected comet, Zanotta-Brewington has a high Q(CN)Afϱ of more than 110 × 1021 molec s−1 cm−1 which decreased with CN activity in March 1992. No reddening is measured from the continuum filters.