  We introduce a novel compact 4-channel beam splitter which is based on a
combination of dichroic coatings and internal total reflection, similar in
concept to the interference double-prism invented by K\"osters 90 years ago.
Used with a rapidly-slewing 50 cm telescope in space, this would allow to
double the presently known gamma-ray bursts at high (>5) redshift within 2
years.

Instrumentation and Methods for Astrophysics