... Spherical aberration, coma, and astigmatism are also easily observed using the star test. ... Off-axis images are complex. ... Fig. ... Diffraction by a circular aperture as a function of defocus for no aberration Airy Disk 1 wave defocus Less than 1 wave defocus Fig. ... Diffraction by a circular aperture as a function of defocus for third-order spherical aberration Paraxial Focus Small distance inside paraxial focus Moderate distance from marginal focus Immediate neighborhood of marginal focus Fig...

... Liyong Liu (NAOC) . Site testing on seeing conditions of the astronomical observatories over China are briefly reviewed, including Xionglong station of NAOC, Gaomeigu station of Yunnan Observatory, Delingha station of Purple Mountain Observatory. ... PDF [3.0€аMB] October 8, 09:55 10:20 . ... In this paper, we will review the site survey activities in the past years, and present the site-testing results on the Oma site, including cloud cover, seeing, water vapor, transparency and sky brightness. ...

The direct detection of gravitational waves is one of those events long-expected by physicists that are nevertheless a significant occurrence which excites the world scientific community as if something unexpected has happened. ... Many rumors leaked ahead of the conference, and the fact that something (that is, a signal corresponding to gravitational waves) was discovered by LIGO (Laser Interferometer Gravitational-Wave Observatory) was discussed on the sidelines. ... arXiv:1602.03868 . ...

We present a catalogue of galaxies for which spatially resolved data on their internal kinematics have been published; there is no apriori restriction regarding their morphological type. The catalogue lists the references to the articles where the data are published, as well as a coded description of these data: observed emission (E) or absorption (A) data, optical (O) or radio (R) data, velocity (V) or velocity dispersion (D), radial profile (1) or 2D field (2). ...