Short time scale pulse stability of the Crab pulsar in the optical band

The fine structure and the variations of the optical pulse shape and phase of the Crab pulsar are studied on various time scales. The observations have been carried out on 4-m William Hershel and 6-m BTA telescopes with APD photon counter, photomultiplier based 4-channel photometer and PSD based panoramic spectrophotopolarimeter with 1$\mu$s time resolution in 1994, 1999, 2003 and 2005-2006 years. The upper limit on the pulsar precession on Dec 2, 1999 is placed in the 10 s - 2 hours time range. The evidence of a varying from set to set fine structure of the main pulse is found in the 1999 and 2003 years data. No such fine structure is detected in the integral pulse shape of 1994, 1999 and 2003 years. The drastic change of the pulse shape in the 2005-2006 years set is detected along with the pulse shape variability and quasi-periodic phase shifts.Comment: 4 pages, 6 figures. To appear in ApSS, in the proceedings of the conference "Isolated Neutron Stars: from the Interior to the Surface", London, April 2006; eds. D. Page, R. Turolla and S. Zan

High-time Resolution Astrophysics and Pulsars

The discovery of pulsars in 1968 heralded an era where the temporal characteristics of detectors had to be reassessed. Up to this point detector integration times would normally be measured in minutes rather seconds and definitely not on sub-second time scales. At the start of the 21st century pulsar observations are still pushing the limits of detector telescope capabilities. Flux variations on times scales less than 1 nsec have been observed during giant radio pulses. Pulsar studies over the next 10 to 20 years will require instruments with time resolutions down to microseconds and below, high-quantum quantum efficiency, reasonable energy resolution and sensitive to circular and linear polarisation of stochastic signals. This chapter is review of temporally resolved optical observations of pulsars. It concludes with estimates of the observability of pulsars with both existing telescopes and into the ELT era.Comment: Review; 21 pages, 5 figures, 86 references. Book chapter to appear in: D.Phelan, O.Ryan & A.Shearer, eds.: High Time Resolution Astrophysics (Astrophysics and Space Science Library, Springer, 2007). The original publication will be available at http://www.springerlink.co