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The results of the multiaperture photometry of Comet Shoemaker-Levy 1991 T2 in the pre-perihelion and P/deVico in the post-perihelion period with the narrowband CN, [C.sub.2] and Blue Continuum (BC) IHW filters are presented. A Haser model of the molecular coma was used for the determination of the parent and daughter scale-lengths and production rates of the radicals. The comets showed some substantial differences between their parent scale-lengths. The CN parent scale-length (at 1.0 AU) was 16 x [10.sup.3] km for Comet Shoemaker-Levy and 39 x [10.sup.3] for P/deVico, the [C.sub.2] parent scale-lengths were respectively 29 x [10.sup.3] and 54 x [10.sup.3] km. Such divergences could be interpreted in the frame of different scenarios of emission of cometary parents, either from a nucleus or from a volume source. The daughter scale-lengths for these comets were quite similar, namely: 306 x [10.sup.3] and 318 x [10.sup.3] km for CN and 69 x [10.sup.3] and 66 x [10.sup.3] km for [C.sub.2]. We determined the A f [rho] parameter for apertures of different radii. A Monte Carlo model of the dust coma was used to obtain the dust ejection velocity. It was of the order of 0.1 km [s.sup.-1] for both comets. The power index of the distribution of the [beta]-parameter of dust particles (ratio of light pressure to the solar gravitation) was of the order of 3 for C/Shoemaker-Levy and close to 2 for P/deVico. The dependence on heliocentric distance ([r.sub.h]) of the radical and dust production rates for P/deVico in the range of 0.7-1.0 AU was described by the power law function [r.sup.[alpha].sub.h] with a power index equal to: 5.55 [+ or -] 0.14 for CN, 5.70 [+ or -] 0.24 for [C.sub.2] and 5.22 [+ or -] 0.19 for dust. Relative abundances of the dynamically new Comet Shoemaker-Levy and short-period P/deVico were quite similar with an enhancement of [C.sub.2] comparing with standard values taken from A'Hearn et al. (1995). Keywords: Comets, composition

The article presents results of CCD photometry in R-band of a dynamically new Comet C/2001 K5 (LINEAR), obtained at a heliocentric distance of about 5.6 AU, after the perihelion passage. Being so distant from the Sun, this comet was extremely active (Af[rho] close to 2000 cm), exhibiting quite well developed dust coma and tail. During the observations, general photometric behavior of the comet with heliocentric distance r was well described by the 2.5n log(r) function with coefficient n = 5. The radial profiles of the coma were found to be undulated, with mean slope of the dependence between cometary magnitude and 2.5 log of aperture radius (at comet distance) equal to [bar.p] = -0.77. The light curve of Comet LINEAR exhibited short-term variability which we attributed to cyclic changes of dust emission, induced by nucleus rotation. Model computations by some authors have revealed that active comets can change their spin status quite substantially even during a single orbital revolution. Thus, attempting to search for a rotation frequency, we have modified the classical PDM approach by including the spin acceleration term. Such DYNAMICALPDM (DPDM) method revealed the most reliable solution for the frequency [f.sub.0] = 0.019048 [+ or -] 0.000013 [h.sup.-1] and its first time-derivative [f.sub.0] = -9.901 [+ or -] 0.046 x [10.sup.-6] [h.sup.-2] (index 'zero' denotes reference to the mid time of the whole observing run), indicating a rapid spin-down of the nucleus. These parameters are equivalent to the rotation period of 52.499 [+ or -] 0.036 h and its relative increment of 0.02729 [+ or -] 0.00013. We present the most probable evolution of the rotation frequency of Comet LINEAR, based on the results of periodicity analysis and a simple, almost parameter independent, dynamical model of nucleus rotation. It is also shown that the DPDM may be an effective tool for determination of a nucleus radius, which provided us with the value of 1.53 [+ or -] 0.25 km for Comet LINEAR. Keywords: Comets; Photometry; Rotational dynamics