Observations of Markarian 421 with the MAGIC Telescope
The MAGIC telescope took data of very high energy γ-ray emission from the blazar Markarian 421 (Mrk 421) between 2004 November and 2005 April. We present a...
Observations of the Blazar 3C 66A with the Magic Telescopes in Stereoscopic Mode
We report new observations of the intermediate-frequency peaked BL Lacertae object 3C 66A with the MAGIC telescopes. The data sample we use were taken in 2009...
Observations of three BL Lacertae objects - Constraints on inhomogeneous relativistically beamed jet models
Multifrequency observations are presented of three BL Lac objects, including the first UV measurements of 0912 + 297 and 1219 + 285. An eight day optical flare...
There were predictions that blazar OJ 287 should have faded in late 1997 or early 1998. The observational background for these predictions is the sudden fade of...
On the Connection of the Apparent Proper Motion and the VLBI Structure of Compact Radio Sources
Many of the compact extragalactic radio sources that are used as fiducial points to define the celestial reference frame are known to have proper motions...
We report results of a spectroscopic campaign carried out at the 10 m Gran Telescopio Canarias for a sample of 22 BL Lac objects detected (or candidates) at TeV...
On the redshift of the very high-energy gamma-ray BL Lac object S2 0109+22
The determination of the redshift of extragalactic gamma-ray sources is of fundamental importance for the interpretation of their emission models and...
Optical and radio variability of the BL Lacertae object AO 0235+16: A possible 5-6 year periodicity
The BL Lacertae object AO 0235+16 is well known for its extreme optical and radio variability. New optical and radio data have been collected in the last four...
Optical spectral characterization of the gamma-ray blazars S4 0954+65, TXS 1515-273, and RX J0812.0+0237
The study of gamma-ray blazars is usually hindered due to the lack of information on their redshifts and on their low-energy photon fields. This information is...