Context. The international Whole Earth Blazar Telescope (WEBT) consortium planned and carried out three days of intensive micro-variability observations of S5 0716+714 from February 22, 2009 to February 25, 2009. This object was chosen due to its bright apparent magnitude range, its high declination, and its very large duty cycle for micro-variations. Aims. We report here on the long continuous optical micro-variability light curve of 0716+714 obtained during the multi-site observing campaign during which the Blazar showed almost constant variability over a 0.5 mag range. The resulting light curve is presented here for the first time.Observations from participating observatories were corrected for instrumental differences and combined to construct the overall smoothed light curve. Methods. Thirty-six observatories in sixteen countries participated in this continuous monitoring program and twenty of them submitted data for compilation into a continuous light curve. The light curve was analyzed using several techniques including Fourier transform, Wavelet and noise analysis techniques. Those results led us to model the light curve by attributing the variations to a series of synchrotron pulses. Results. We have interpreted the observed microvariations in this extended light curve in terms of a new model consisting of individual stochastic pulses due to cells in a turbulent jet which are energized by a passing shock and cool by means of synchrotron emission. We obtained an excellent fit to the 72-hour light curve with the synchrotron pulse model.

We have carried out a continuous multiband photometric monitoring of the nuclear activity of comet 29P/Schwassmann–Wachmann 1 from 2008 to 2010. Our main aim has been to study the outburst mechanism on the basis of a follow‐up of the photometric variations associated with the release of dust. We have used a standardized method to obtain the 10‐arcsec nucleus photometry in the V, R and I filters of the Johnson–Kron–Cousins system, which are accurately calibrated with standard Landolt stars. The production of dust in the R and I bands during the 2010 February 3 outburst has been also computed. We conclude that the massive ejection of large (optically thin) particles from the surface at the time of the outburst is the triggering mechanism to produce the outburst. The ulterior sublimation of these ice‐rich dust particles during the following days induces fragmentation, generating micrometre‐sized grains, which increase the dust spatial density to produce the outburst in the optical range as a result of the scattering of sunlight. The material leaving the nucleus adopts a fan‐like dust feature, formed by micrometre‐sized particles that decay in brightness as it evolves outwards. By analysing the photometric signal measured in a standardized 10‐arcsec aperture using the phase dispersion minimization technique, we have found a clear periodicity of 50 d. Remarkably, this value is also consistent with an outburst frequency of 7.4 outbursts per yr deduced from the number of outbursts noticed during the effective observing time.

Aims. We carried out a continuous monitoring of comet 29P/Schwassmann-Wachmann 1 by using medium aperture telescopes with the aim of studying the activity and outburst mechanisms of this comet on the basis of photometric variations. Methods. We used a standardized method to obtain the coma photometry in the R filter of the Johnson-Kron-Cousins system. Some abrupt changes observed in the brightness of SW1 suggest important variations in surface activity with time.Results. During our 2002−2007 observational campaign we detected 28 outbursts (of 1 mag or larger) in 29P/SchwassmannWachmann 1. A typical outburst is characterized by a rapid increase towards maximum (in a few hours) and a slower decrease toward the quiescent level (in 3−4 days). Given the effective observing time, the average outburst rate is 7.3 events per year. Despite well-sampled data, no signs of a clear periodicity in the outburst occurrence has been found, thus confirming the unpredictability of the activity of this comet.

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Highligths-Comet 107P/WH was active in 1949, 1979, 1992, 2005, and 2009 .-Its age can be measured. We find T-AGE=4700 comet years, WB-AGE=7800 cy.-This is a methuselah comet very near to dormancy, being temporarily rejuvenated.-The diameter Deffe=3.67±0.06 km, and the rotational period, Prot=6.093±0.002 h.-There are three members in the graveyard of comets, 107P, 133P and D/1891W1.