... Bad Astronomy . ... I think I will break from my usual format of Bad Astronomy/ Good Astronomy by saying that the way we define seasons currently is not strictly bad, but I feel (in my opinion!) that it could be better. The definition of when the seasons begin is at the moment of solstice or equinox; that is, winter (in the north) starts on December 22 nd and summer starts on June 22 nd . ... Now imagine breaking up the Sun's 46 degree up-and-down yearly swing into 1 day intervals. ...

... The Raw Images . Table 1: List of Viking Orbiter Images of the "Face on Mars" . ... Processing the Face Images . ... In July, 1976, Viking Orbiter 1 was acquiring images of the Cydonia region of Mars as part of the search for potential landing sites for Viking Lander 2. ... Using the height field, it is also possible to view the "Face" from different look directions, by mapping the Viking Orbiter image directly on the the topography and then placing the "viewer" at different locations. ... Mars . ...

The Face on Mars . ... The Raw Images . Table 1: List of Viking Orbiter Images of the "Face on Mars" . ... Processing the Face Images . Table 2: Dimensions of Mercator Projected Images of "The Face on Mars" . Map Projected Images . ... Processing the "Face on Mars" Images . ... This page will provide interested persons with both the raw Viking images, transformed to GIF format, and a brief tutorial (with examples) of image processing techniques applied to create "better looking" images. ...

... Usage and Examples . Example 1: Point source . Example 2: Correcting for bad pixels . Example 3: Point source with explicit position . Example 4: Specifying an external detector map for an extended source . Example 5: Using an RMF dataset to specify the energy grid . ... Example 7: Getting the unvignetted ARF . Example 8: Finding the cross-region ARF . ... Effective Area, Filter Transmission, Quantum Efficiency and Grating attenuation . ... Encircled energy correction . ...

This section of library contains information about "classic" Star Catalogs. ... For a Henry Draper Catalog 272149 stars have received a total of 531,211 identifications in 7 сatalogs: . 270456 - in Astrographic Catalogue ( "Carte du Ciel", 4M), . 251943 - in Guide Stars Catalog (GSC), . ... A file with information on the components of 1788 of multiple systems in catalog HDEC (3681 component, or a combination thereof, with 4054 recording). ... A file with information about 21971 variable stars. ...

... AA(Max-Planck-Institut f r Radioastronomie, 53121 Bonn, Germany), AB(Max-Planck-Institut f r Radioastronomie, 53121 Bonn, Germany), AC(Max-Planck-Institut f r Radioastronomie, 53121 Bonn, Germany), AD(Special Astrophysical Observatory, Nizhnij Arkhyz, 357147, Russia), AE(Stockholm Observatory, 13336 Saltsj baden, Sweden) . ... 241B Structural and chemical changes during the AGB and post-AGB evolution are discussed with respect to two recent observational and theoretical findings. ... Abstract Text ....

SAI 175 anniversary . ... Moscow University . Search for in SAI Moscow University Search for in Russian astronomical resources . ... SAI Astronomical Databases . ... Browse SAI Software archive(ftp.sai.msu.su) . ASTRONET.RU - Russian Astronomical Network (available in translit also) . ... SAI Supernovae Research Group . ... Department of the Galaxy and Variable Stars (in Russian) . Sternberg Astronomical Institute Seminars . ... All-Russian Astronomical Olympiad (in Russian) . ...

... Contents . ... Sidereal time . ... Mean longitude of the Moon, mean elements of the Moon's orbit and equator . ... Ephemeris for physical observations of the Sun . ... Ephemeris for physical observations of the Moon . ... Matrix elements for conversion to CIRS . ... Conversion of mean time to sidereal time (with accuracy 0.01 s ) . ... Conversion of sidereal time to mean time (with accuracy 0.01 s ) . ... Conversion of mean time to sidereal time (with accuracy 0.001 s and 0.0001 s ) . ...

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