The following people at the telescopes listed have agreed to participate, at varying levels, in this AGN monitoring program.


Waveband Contact Person Telescope
Radio Margo F. Aller (UMRAO) UMRAO
  Anne Lahteenmaki Metsahovi
Infra Red Josh Bloom (Berkeley) PAIRITEL
Optical Paul Boltwood Boltwood
  Jim Buckley & Vicky Kuen Lee Antipodal
  Patrick Charlot Bordeaux
  Mike Carini 0.6m, Bell Observatory
  Omar Kurtanidze & Maria Nikolashvili 70cm & 125cm, Abastumani Observatory
  Chuck Pullen Coyote Hill Observatory
  Juan Antonio Ros Sbadell
  Alberto C. Sadun New Mexico Skies Observatories
  Aimo Sillanpaa Tuorla
  Gino Tosti Perugia
  Trevor Weekes FLWO 48-inch
  T. Montaruli WIYN 0.9m

UTDate: The UT Date on which the observations were taken with the Whipple 10m telescope.

Rate (Crab): The gamma-ray rate (in Crabs) detected from this target. If gamma-rays were not detected above the 1 sigma level, an upper limit is quoted, again in Crabs. The peak detection threshold for the 10m telescope is estimated to be approximately 350 GeV.

Rate Error (Crab): The error on the reported gamma-ray rate in Crab units.

Duration (Hours): The duration, in hours, of the gamma-ray on-source observation at the Whipple 10m.

UTC Start: The time, in UTC, at which the Whipple observations started.

Click on the name of the AGN to access the most recent data:
NOTE: March 2008 -Lightcurve-updating has been abandoned temporarily. Watch this space: Lightcurves will be back online soon.

Markarian 421

H 1426+428

Markarian 501

1ES 1959+650

1ES 2344+514  

The Whipple collaboration pioneered the Imaging Atmospheric Cherenkov Technique (IACT) for the detection of Very High Energy (VHE) gamma rays. The Whipple 10 m gamma-ray telescope was located at the Fred Lawrence Whipple Observatory in Southern Arizona in the United States. The predecessor to VERITAS (Very Energetic Radiation Imaging Telescope Array System), this telescope was in operation from 1968 until its decommissioning in 2013, and detected the first TeV gamma-ray source, the Crab Nebula in 1989 (Weekes et al., 1989).

The Davies-Cotton reflector held 248 hexagonal mirrors and provided a total reflecting area of 75 m^2.  The camera was located at the focal point and (ultimately) contained 379 PhotoMultiplier Tubes (PMTs) with a field of view of ~2.6 degrees and an angular resolution of 0.117 degrees. The telescope operated between 300 GeV and 10 TeV.


The primary emphasis of the collaboration's research effort was the search for and study of gamma ray sources in the energy range of 100 GeV - 10 TeV. Since the mid-2000's, the telescope's primarily concern was long term blazar monitoring in the search for interesting or increased activity and it also acted as an alert system for the VERITAS array. For the observing season 2010/11 a number of known TeV blazars including the High frequency BL Lacs (HBLs) Mrk421, 1ES2344+514, 1ES1959+650 and 1ES0229+200 were observed and the nightly lightcurves are posted below.


Blazar Lightcurves

Markarian 421.

Mrk 421 the closest known TeV blazar located at a redshift of z=0.031, was the first extragalactic source detected at TeV energies by a ground-based instrument in 1992 (Punch et al 1992). This HBL is one of the most active TeV blazars and exhibits extreme variability, on the timescale of hours. Mrk 421 has been monitored closely and studied extensively since its discovery



1ES0229+200 is a HBL at a distance of z=0.14. Due to its unusualy hard TeV spectrum it is an excellent candidate for Extragalactic Background Light (EBL) studies



1ES1959 (HBL, z=0.047) was first discovered as a TeV gamma-ray emitter in 1998 by the Seven Telescope Array [Nishiyamma T et al., 1998]. In 2002, the Whipple 10m detected flaring activity from 1ES1959 up to 5 times the Crab Nebula flux [Holder et al, 2003]



1ES2344 is a HBL at a redshift of z=0.044. The Whipple Collaboration reported a weak signal from the source between 1999-2001.


The 2007-2008 observing season at the Whipple 10m began on 071004. During the May - June 2008  darkrun, Markarian 421, H1426+428, Markarian 501 and H1426+428 will be monitored on a nightly basis. Please take whatever data you can on these objects during that time.
The Whipple 10m Telescope was used to monitor five of the known TeV blazars, 1ES2344+514, 1ES1959+650, Markarian 421, H1426+428 and Markarian 501, during the 2005-2006 observing season and will continue to monitor these objects during the 2006-2007 observing season. The observing timetable for the currrent darkrun is shown below. The gamma-ray lightcurves will be posted soon and will be updated on a nightly basis. We encourage observers at other wavelengths and in other timezones to participate in this monitoring campaign. For more information on this monitoring campaign at Whipple, contact Deirdre Horan or Trevor Weekes. The targets will be observed at the following times of the year:
  • 1ES2344+514 : October 2007 - January 2008;
  • 1ES1959+650 : October 2007 - December 2007; April 2008 - June 2008
  • Markarian 421 : December 2007 - June 2008
  • H1426+428 : January 2008 - June 2008
  • Markarian 501 : March 2008 - June 2008
The 2007-2008 observing season began on 071004. Scroll down for more information.