The High-Speed UBVRI Photometer MCCP

Das MCCP am 0.8m Teleskop auf dem Wendelstein.

For precise multicolour aperture photometry of fast variable phenomena the Multi-Channel Multi-Colour Photometer MCCP has been developed. This instrument uses three optical fibers which are positioned by computer control onto three light sources (e.g. the variable star, a nearby comparison and the sky background) in the focal plane of the telescope. The fiber ends repectively form the entrance slits of three prism-spectrographs. The individual spectra are projected on fiber bundels which allow to select 5 overlapping broad band regions corresponding to the Kron-Cousins UBVRI colours. The colour channels of each lightsource feed 5 photon counting photomultipliers which are thermoelectrically cooled to -20 degree Celsius. The output signals are recorded by a real time multi-tasking VME-Bus computer system. This measuring method yields simultaneous UBVRI data of three light sources with a maximum time resolution of 1 ms. Peripheric devices include an on-line graphics system which allows to monitor selected light curves and an autoguider system which controls the star centering in the fiber diaphragms.

Schematic drawing of th MCCP

Specifications of the MCCP:

Simultaneous measuring channels:3
Diameter of measuring diaphragms:0.6/0.8/1.0 mm
Simultaneous colour channels:3 x UBVRI
Detectors:15 HAMAMATSU Photomultipliers
Time resolution:<= 1 ms
Max. count rate per channel:<= 2 10E5 cts/s
Typical dark count rates:<= 5 cts/s
Spectral range:350 - 900 nm
App. brightness range:V = 8...15 mag.( at 80cm telescope)

For further details see:

Barwig,H., Schoembs,R., Buckenmeyer,C., 1987:
"A multi-channel multi-colour photometer for high time resolution", Astron. Astrophys., 175, 327.

Mantel,K.H., Barwig,H., 1994:
"Multichannel-Multicolour Photometry - experiences from a long term observing campaign", in Proc. of the NATO Advanced Research Workshop on "The Impact of Long-Term Monitoring on Variable Star Research", November 1993, Ghent, Belgien, NATO ASI series C436, eds. C.Sterken, Groot, 329.

Barwig,H., Mantel,K.H., Kiesewetter,S., 1998:
"Impact of Fiber Optics on Photometry - Design of two High-Speed Multichannel Instruments", in Proc. of the meeting held in Puerto de la Cruz, Canary Islands, Spain, 2-4 December 1997 on "Fiber Optics in Astronomy III", eds. S.Arribas, E.Mediavilla, F.Watson, Astronomical Society of the Pacific, Conference Series, Vol. 152, 320.

Last revision: July 2001
email: Heinz Barwig (