Related papers: Intraday Optical Variability of BL Lacertae

We report on I band photometric observations of 21 stars with spectral types between M8 and L4 made using the Isaac Newton Telescope. The total amount of time for observations which had a cadence of <2.3 mins was 58.5 hrs, with additional…

Long-term (up to 10000d) monitoring has been undertaken for 41 Seyferts in the near-IR (JHKL). All but 2 showed variability, with K ampl in the range <0.1 to > 1.1 mags. The timescale for detectable change is from about one week to a few…

We report the results of photometric observations of the blazars Mrk 421 and 3C 454.3 designed to search for intraday variability (IDV) and short-term variability (STV). Optical photometric observations were spread over eighteen nights for…

About twenty years of radio observations in five bands (from 4.8 to 37 GHz) of the BL Lac object GC 0109+224 (S2 0109+22, RGB J0112+227), are presented and analysed together with the optical data. Over the past ten years this blazar has…

We report the variable X-ray emission from BL Lacertae detected in the ASCA ToO observation conducted during the EGRET and RXTE pointings, coincident with the 1997 July outburst. The source showed a historically high state of X-ray,…

We present time series data on the variable stars of the galactic globular cluster Messier 3 (M3). We give BVI light curves for 226 RR Lyrae, 2 SX Phe and 1 W Vir type variables, along with estimated fundamental photometric parameters such…

The BL Lac object S5 0716+71 was target of a coordinated and global multi-frequency campaign to search for rapid and correlated variability and signatures of the inverse-Compton catastrophe. Here we present first results obtained from a…

The BTr and UBr satellites observed $\beta$ Lyrae from May to October 2016 to continuously monitor light-curve instabilities with the time resolution of about 100 mins. An instrumental problem affecting localized patches on the BTr CCD…

We have observed the post common envelope binary WD0137-349 in the near infrared $J$, $H$ and $K$ bands and have determined that the photometry varies on the system period (116 min). The amplitude of the variability increases with…

Since the launch of the Fermi satellite, BL Lacertae has been moderately active at gamma-rays and optical frequencies until May 2011, when the source started a series of strong flares. The exceptional optical sampling achieved by the…

The optical-UV and X-ray instruments on-board XMM-Ndewton provide an excellent opportunity to perform simultaneous observations of violently variable objects over a broad wavelength range. The UV and X-ray bright BL Lac object PKS 2155-304…

Thorough analysis of the multicolour CCD observations of the RRab-type variable, CZ Lacertae is presented. The observations were carried out in two consecutive observing seasons in 2004 and 2005 within the framework of the Konkoly Blazhko…

We report on our optical monitoring of the BL Lac object S5 1803+78 from 1996 to 2011. The source showed no clear periodicity, but a time scale of about 1300 days between major flares is possibly present. No systematic trend of the color…

PKS 2155-304, the brightest BL Lac object in the ultraviolet sky, was monitored with the IUE satellite at ~1 hour time-resolution for ten nearly uninterrupted days in May 1994. The campaign, which was coordinated with EUVE, ROSAT, and ASCA…

By studying the variability of blazars across the electromagnetic spectrum, it is possible to resolve the underlying processes responsible for rapid flux increases, so-called flares. We report on an extremely bright X-ray flare in the…

The variability of blazars in the X-ray and optical regions informs both the physics of their emitting region and places demands on the observer if a program requires that the object be bright or faint. The extensive simultaneous X-ray and…

We report on spectral variability of the blazar 3C 279 in the optical to X-ray band between MJD 55100 and 58400 during which long-term radio variability was observed. We construct light curves and band spectra in each of the optical…

We present results of our intra-night optical flux monitoring observations of S5 0716+714 done simultaneously in gRI filters. The observations were done using Multicolor Imaging Telescopes for Survey and Monstrous Explosions (MITSuME)…

Blazars are characterized by large amplitude and fast variability, indicating that the electron distribution is rapidly changing, often on time scales shorter than the light crossing time. We study the time dependent behavior of the…

We report the first results of a systematic investigation to characterize blazar variability power spectral densities (PSDs) at optical frequencies using densely sampled (5--15 minutes integration time), high photometric accuracy…