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We present a new technique for detecting structure on Mpc scales in the Lyα forest. The technique is easy to apply in practice since it does not involve absorption‐line fitting, but rather is based on the statistics of the transmitted flux. It identifies and assesses the statistical significance of regions of overdense or underdense Lyα absorption and is fairly insensitive to the quality of the data. Using extensive simulations, we demonstrate that the new method is significantly more sensitive to the detection of large‐scale structure in the Lyα forest than a traditional two‐point correlation function analysis of fitted absorption lines.

Twenty-six QSO candidates from the Jodrell Bank 966-MHz survey have been observed spectroscopically at the Multiple Mirror Telescope⋆. Nineteen are emission-line QSOs and redshifts are given for these. Four have smooth, featureless spectra and are classified as BL Lacertae-type objects. The remaining three objects are galactic stars.

Multidimensional cosmologies allow for variations of fundamental physical constants over the course of cosmological evolution, and different versions of the theories predict different time dependences. In particular, such variations could manifest themselves as changes of the proton-to-electron mass ratio ? = mp/meover the period of ~1010yr since the moment of formation of high-redshift QSO spectra. Here we analyze a new high-resolution spectrum of the z= 2.81080 molecular hydrogen absorption system toward the QSO PKS 0528-250 to derive a new observational constraint to the time-averaged variation rate of the proton-to-electron mass ratio. We find | /? |<1.5×10?14yr-1, which is much tighter than previously measured limits.

0957 + 561 A, B are two QSOs of mag 17 with 5.7 arc s separation at redshift 1.405. Their spectra leave little doubt that they are associated. Difficulties arise in describing them as two distinct objects and the possibility that they are two images of the same object formed by a gravitational lens is discussed.

Edited by F. D. Kahn, D. Reidel Publishing Company (ISBN 90-277-1325-1) 1981. Price Dfl. 125.00/U.S. $54.50. Approx. 448 pp.

Spectroscopy of thez=2.0763 absorption line system in A2206-199N shows that it has a very large hydrogen column density (5×1020 cm-2) but extremely weak absorption due to heavy elements. We discuss the possibility that the gas cloud causing this absorption system may be exceptionally metal-poor.

THE purpose of this letter is to draw attention to the very high redshift, z = 3.40, of the QSO OH471.

Relativity and the Question of Discretization