Although geographic object based image analysis (GEOBIA) has been successfully applied to derive local maps (1-10s km) from very high spatial resolution (VHR) image data (pixels < 1.0 x 1.0 m), its potential for automatically mapping large areas remains unknown. The aim of this study was to create and apply a GEOBIA method to automatically map land cover classes in subsets with different enviro...

We present multi-colour photometry of four field ultracool dwarfs with the triple-beam photometer ultracam. Data were obtained simultaneously in the Sloan-g band and a specially designed narrow-band NaI filter. The previously reported 1.8-hr period of Kelu-1 is here recovered in the g-band, but the lack of any significant variability in the NaI light of this object precludes any conclusion as t...

In this paper, we present high time-resolution observations of GW Librae (GW Lib) and SDSS J161033.64−010223.3 (SDSS 1610) – two cataclysmic variables which have shown periodic variations attributed to non-radial pulsations of the white dwarf (WD). We observed both these systems in their quiescent states with ULTRACAM on the Very Large Telescope (VLT) and the University of Cape Town Photometer ...

We present z′-band secondary eclipse photometry of the highly irradiated hot Jupiter WASP12b using ULTRACAM on the 4.2 m William Herschel Telescope. We measure a decrease in flux of δ = 0.130 ± 0.013 per cent during the passage of the planet behind the star, which is significantly deeper than the previous measurement at this wavelength (0.082± 0.015 per cent). Our secondary eclipse is best fitt...

We present high time-resolution multicolour observations of the quiescent soft X-ray transient XTEJ1118+480 obtained with ULTRACAM. Superimposed on the double-humped continuum g ′ and i -band lightcurves are rapid flare events which typically last a few minutes. The power density spectrum of the lightcurves can be described by a broken power–law model with a break frequency at ∼2mHz or a power–...