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Cosmology. Epoch of star formation. ApJ 511, 16-33 (1999). The observed level of diffuse extragalactic light in the visible bands requires a high redshift of galaxy formation, z � (3-4). Otherwise, the produced flux of extragalactic flight at optical bands exceeds the current observational limits.

Gamma rays. Burst properties. ApJ 511, L89-L92 (1999). GRB 920229 as four extreme and unprecedented properties. A spike near the end of the burst has a rise in brightness with an e-folding timescale of 220 � 30 microseconds. A fall in brightness has an e-folding timescale of 400 � 100 microseconds. A large change in spectral shape takes place over a time of 768 microseconds. And the spectrum of the entire burst has a sharp spectral cutoff to high energies with DE/E = 18%. These properties severely constrain fireball models of bursts. The energy production region must be smaller than 66 km. Ejected shells must have a dispersion of the Lorentz factor of less than roughly 1% along the particular radius. And the angular size of the radiation emission region is of the order of 1� (one arcminute) as viewed from the burst center. !!

Gravitation. Yilmaz metric. astro-ph/9902232, 16 Feb. 1999, to appear in ApJ. GRB 990123 may have radiated more than a solar mass equivalent in just its gamma-ray emissions. This requires an implausibly efficient conversion process. The Yilmaz metric allows neutron stars of up to 10 solar masses. This would provide a more plausible source of the gamma rays, it is therefore an observation favoring the Yilmaz metric over Einstein's.

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