HQM - Hamburg Quasar Monitoring




HQM was designed to find at least one example of lightcurves with microlensing features. This major goal was not reached. HQM was not designed to create a homogenous and complete sample of lightcurves of quasars and AGN - although, at the end this would have been a statistical alternative to the main goal. We have sampled a great list of quasars and numbers of datapoints and lightcurves but all we do not have is a complete sample.The design criteria had been too inhomogenous to reach any form of completeness. Nevertheless there had been a plenty of interesting details of quasar variability during the years of HQM observations.


This quasar was first observed from us in 1988 and was found behind a tidal arm of a foreground merging galaxy system AN 0248+430 (Borgeest, Dietrich, Hopp, Kollatschny, Schramm, AA, 243, 93, 1991). Out of this unusal constellation GC0248+430 was observed very feequently.


The lightcurve of the blazar 1641+399 (3C345) showed a very heavy outburst between 1991 and 1993 with three prominent peaks. The HQM program realized the beginning increase in february 1991 (Schramm, Borgeest, IAU Circ. 5191, 1991). With observations as often as possible we followed the lightcurve with at least more than 600 data points (Schramm et al., AA 278, 391, 1993).


A very sudden outburst occurred February 6, 1992 (Schramm, v.Linde, Borgeest, Nieser, IAU Circ. 5453, 1992). The brightness increased by 0.7 magnitudes and faded to the earlier level some days later(v. Linde, Borgeest, Schramm, et. al., AA 267, L23, 1993. During this outburst the Compton EGRET team reported an outburst as well in the gamma range (Fichtel et al., IAU Circ. 5460, 1992).


A status report on HQM data apeared in three papers:

  1. Borgeest, Schramm, Low amplitude variability in quasars, AA, 284, 764, 1994
  2. Schramm, Borgeest, Kühl, v.Linde, Linnert, Lightcurves of weakly variable objects, AA Suppl. 104, 473, 1994
  3. Schramm, Borgeest, Kühl, v. Linde, Linnert, T. Schramm, AA Suppl., 106, 349, 1994


Similar to 3C345 several outburst dominate its lightcurve. Next to a violent flickering the main outbursts or flares last about one month and lay in the order of one to two magnitudes. 0420-014 has been observed in many wavelengths and some outbursts have been seen as well by the EGRET Gamma Ray observatory (Wagner, et al., AA 298, 688, 1995).


Another source of violent variability similar to 3C345 and 0420-014 is 1510-089 which was observed very densly.


Additionally to some of the objects listed above, several blazars have been observed with very good sampling. Some examples are given here:

0219+428 (3C66A)




0851+202 (OJ287)







This bright object was dicoverd by the Hamburg Survey (Groote et al., AA, 223, L1, 1989). Its variability was followed by the HQM group since 1990. Multi wavelength observations were published in 1995 (Reimers et al., AA 303, 449, 1995).



data, graphics and images may not be used without permission.
contact:Jochen Schramm, Hamburger Sternwarte.