Call for monitoring of polars

(from vsnet 436, Beuermann et al.)

Dear observers of the VSNET,

in the last years the number of known magnetic cataclysmic variables of AM Her-type (polars) has dramatically increased, mainly thanks to the ROSAT X-ray Sky Survey. Compared to dwarf novae, these systems offer an interesting possibility to study directly the change of the mass transfer rate, as no disc serving as intermediate buffer is present.

While many follow-up observations were performed in the optical, UV and X-ray regime, the knowledge about the long-term behaviour of these objects is sparse, e.g. the prototype AM Her shows irregular changes between high and low accretion rates, while AR UMa showed only a few short eruptions over the last 30 years.

To approach this problem, we would like to ask you to include some of the systems given below into your observing programs. Even though we chose the brightest systems they might be to faint to be observed in a low state, but it still would be important to know at least when and for how long the systems are 'turned on'. Furthermore, it will be of extreme help to know the state of these systems in planning observations with ground & space based telescopes, e.g. during a major campaign on AM Her running in 1996, including ROSAT, IUE, HST and ground based telescopes

Find below a list of interesting systems. Coordinates are given for the equinox 2000. The magnitudes are given in the V-band except when explicitely 'B'.

We will come up with updates of this list whenever necessary. Furthermore, we provide finding charts through our World-Wide-Web server at


We would appreciate your help in this project.

With best regards and best wishes for a good New Year 1996,

 Klaus Beuermann 
 Vadim Burwitz   
 Boris Gaensicke 
 Klaus Reinsch

Universitaetssternwarte Goettingen
Geismarlandstr. 11 
37083 Goettingen



List of targets

VSNET charts for observing polars

in PostScript:

Return to HomePage