We report on a multi-epoch campaign of rapid optical/X-ray timing observations the superbright 2018 outburst MAXI J1820+070, black hole low-mass X-ray binary system. The spanned 80 days in initial hard-state, and were taken with NTT/ULTRACAM GTC/HiPERCAM optical (ugriz filters at time resolutions 8--300 Hz) ISS/NICER X-rays. find (i) growing anti-correlation between lightcurves, (ii) steady, po...

ABSTRACT We present a rapid timing analysis of optical (HiPERCAM and ULTRACAM) X-ray (NICER) observations the transient Swift J1858.6−0814 during 2018 2019. The light curves show relatively slow, large amplitude (∼1 mag in gs) ‘blue’ flares (i.e. stronger at shorter wavelengths) on time-scales ∼minutes as well fast, small (∼0.1 ‘red’ longer ∼seconds. are consistent with reprocessing optically t...

Since a few years, digital frame cameras are being used for the recurrent conventional photogrammetric mapping tasks within Flanders (Belgium). As a result, area-wide, but mixed-sensor-type (Ultracam, DMC, ...) time series of digital airborne imagery are emerging. Since only recently, a trend can be observed that this imagery is increasingly used for environmental mapping tasks, such as agricul...

We present the discovery of optical/X-ray flux correlations on rapid timescales in the low/hard state of the Galactic black hole GX 339–4. The source had recently emerged from outburst and was associated with a relatively-faint counterpart with mag V ≈17. The optical (VLT/ULTRACAM) and X-ray (RXTE/PCA) data show a clear positive cross-correlation function (CCF) signal, with the optical peak lag...

NN Ser is a non mass-transferring pre-cataclysmic variable containing a white dwarf with a mass of ∼ 0.5M⊙ and an M dwarf secondary star with a mass of ∼ 0.2M⊙. Based on the data detected by the high-speed CCD camera ULTRACAM, it was observed that the orbital period of NN Ser is decreasing, which may be caused by a genuine angular momentum loss or the presence of a third body. However, neither ...

We present high time-resolution multicolour optical observations of the quiescent X-ray transients GRS 1124–684 (=GU Mus) and Cen X-4 (=V822 Cen) obtained with ULTRACAM. Superimposed on the secondary stars’ ellipsoidal modulation in both objects are large flares on time-scales of 30–60 min as well as several distinct rapid flares on time-scales of a few minutes, most of which show further varia...

We report on the search for optical bursts from J1819–1458, a member of the recently discovered Rotating Radio Transients (RRATs). J1819–1458 exhibits 3 millisecond bursts with a peak flux of f ν = 3.6 Jy every ∼ 3.4 minutes, implying that it is visible for only ∼ 1 second per day at radio wavelengths. Assuming that the optical light behaves in a similar manner, the most sensitive way of detect...

The so-called German camera evaluation project was initiated by the German society of Photogrammetry, Remote Sensing and Geoinformation (DGPF) in order to allow for comprehensive empirical test on photogrammetric digital airborne camera systems. During this test, the digital camera systems DMC, Ultracam-X, ADS40 (2nd generation), JAS-150, Quattro DigiCAM and AIC-x1 were flown in the test site V...

ABSTRACT We present simultaneous, multicolour optical light curves of the companion star to black-widow pulsar PSR J2051−0827, obtained approximately 10 yr apart using ULTRACAM and HiPERCAM, respectively. The confirm previously reported asymmetry in which leading hemisphere appears be brighter than trailing hemisphere. HiPERCAM curves, however, do not show this asymmetry, demonstrating that wha...

Digital aerial cameras have replaced analog film cameras. An information contents corresponding to aerial photos up to 2010 was only possible with digital system cameras as Vexcel Ultracam and Z/I Imaging DMC or line scanning cameras as Leica Geosystems ADS80 or Jena Optronic JAS-150. Now with very large size CCDs the panchromatic band of the DMC II has between 140 and 256 Mega pixels from one ...