Related papers: Multiwavelength Observations of a Flare from Marka…
Markarian 501, a nearby (z=0.033) X-ray selected BL Lacertae object, is a well established source of Very High Energy (VHE, E>=300 GeV) gamma rays. Dramatic variability in its gamma-ray emission on time-scales from years to as short as two…
The BL Lacertae object Markarian 501 was identified as a source of gamma-ray emission at the Whipple Observatory in March 1995. Here we present a flux variability analysis on several times-scales of the 233 hour data set accumulated over…
We present observations of the gamma-ray blazar Markarian 501 between April 17 and May 5, 2009, with the Whipple 10-m telescope, VERITAS, the Fermi Large Area Telescope (LAT), Swift and RXTE as part of a 4.5-month multi-wavelength campaign.…
The Very High Energy (VHE) gamma-ray emission of the closest BL Lacertae objects Markarian 501 and Markarian 421 has been observed by the CAT telescope in 1997 and 1998. In 1997 Mrk 501 exhibited a remarkable series of flares, with a VHE…
The blazar Markarian 501 (Mrk 501) was observed at energies above 0.10 TeV with the MAGIC telescope from May through July 2005. The high sensitivity of the instrument enabled the determination of the flux and spectrum of the source on a…
We present X-ray observations of the BL Lacertae (BL Lac) object Markarian 501 (Mrk 501), taken with the Rossi X-ray Timing Explorer in 1998 May as part of a multi-wavelength campaign. The X-ray light curve shows a very rapid flare in which…
The blazar Markarian 501 (Mrk 501) was observed above 100 GeV with the MAGIC Telescope during May, June and July 2005. The high sensitivity of the instrument made possible the detection of the source with high significance in each of the…
The very high energy (VHE; E $>$ 100 GeV) blazar Markarian 501 was observed between April 17 and May 5 (MJD 54938--54956), 2009, as part of an extensive multi-wavelength campaign from radio to VHE. Strong VHE $\gamma$-ray activity was…
Markarian 501 is a high-peaked BL Lacertae object and has undergone many major outburst since its discovery in 1996. As a part of the multiwavelength campaign, in the year 2009 this blazar was observed for 4.5 months from March 9 to August…
We present multi-wavelength observations of the very high energy (VHE, E >250 GeV) gamma-ray sources Mrk 421 and Mrk 501. The VHE data presented here were taken with the Whipple Observatory 10m gamma-ray telescope. In the Mrk 421 campaign,…
The TeV BL Lac object Markarian 501 has been the subject of a 4.5 month multi-instrument campaign conducted in 2009, which provided an excellent temporal and energy coverage from radio to very high energy gamma rays (>100 GeV, VHE). During…
The well-studied VHE (E >100 GeV) blazar Mrk 501 was observed between March and May 2008 as part of an extensive multiwavelength observation campaign including radio, optical, X-ray and VHE gamma-ray instruments. Mrk 501 was in a low state…
We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of February, 2010 when an extraordinary flare reaching a level of $\sim$27~Crab Units above 1~TeV was measured in…
Markarian 501, a BL Lac object well-known as a high energy gamma-ray source, has exhibited several epochs of very high energy (VHE) gamma-ray flaring events when its synchrotron peak frequency shifted above $10^{17}$ Hz, a signature of…
Mrk 501 is one of the brightest blazars at TeV energies and has been extensively studied since its first VHE detection in 1996. Our goal is to characterize in detail the source gamma-ray emission, together with the radio-to-X-ray emission,…
Mrk 501 has been in a state of very high flux in X-rays and VHE gamma-rays during 1997. In July 1997 near its hitherto maximum X-ray brightness intense multifrequency observations of Mrk 501 have been performed at radio, near infrared,…
Very high energy gamma-ray emission from the BL Lac object Markarian 421 has been detected over three observing seasons on 59 nights between April 1992 and June 1994 with the Whipple 10-meter imaging Cherenkov telescope. During its initial…
The Very High Energy (VHE) gamma-ray emission of the BL Lacertae objects Markarian 501 and Markarian 421 has been observed by the CAT Imaging Atmospheric Cherenkov Telescope in 1997 and 1998. The spectrum extraction method is presented, and…
A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on…
Mrk501 is a very high-energy (VHE) gamma-ray blazar located at z=0.034. During a period of two weeks in July 2014, the highest X-ray activity of Mrk501 was observed in ~14 years of operation of the Neil Gehrels Swift Gamma-ray Burst…