... The calibration of astrophysical spectra in wavelength based on calibration lamp data suffers from different kinds of uncertainties. Besides inaccuracies in the observational phase, common data reduction practice adds ``pixelation'' errors, due to the fact that the centering method does not use the correct PSF. These model mismatch errors depend, for a given feature, on the sub-pixel location of the line center (David & Verschueren, private communication). ...

... Bad Astronomy . ... Bitesize Astronomy . ... Bad Astro Store . ... Slacker Astronomy . ... Keep Bad Astronomy close to your heart, and help make me filthy rich. ... Life Under the Moon . ... Seeing Jupiter's Moons . ... Time Zones and the Spherical Earth . A Companion to the Earth? ... December 19, 1999) . ... Big Moon, Little Moon . ... How Big is the Moon? ... 14, 2000) . ... 2008 Phil Plait. ... Subscribe to the Bad Astronomy Newsletter! Talk about Bad Astronomy on the BA Bulletin Board! ...

... we show that the comparison between the calculated and observed numbers of the most ``fragile'' (from the point of view of the binary evolution scenario )   galactic binary types (such as X-ray low-mass X-ray binaries (LMXB), cataclysmic variables (CV),   Be-stars   with compact companions, relative number of visible binary radiopulsars   with normal and compact secondary components) impose certain constraints on the feasible initial ... Phenomenological Kick Velocity . ...

... Fitting the observed dependence includes calculations of the polarization cross-sections averaged over particles orientation and size distribution, their normalization and the comparison of obtained dependencies with Serkowski's curve representing observational data for a chosen star. ... Variations of the polarization factors with wavelength are shown in Fig. 16 for homogeneous spheroidal particles with PF orientation. ... The distinction between prolate and oblate spheroids is also clearly seen. ...

Disastrous earthquakes happen 100 to 200 times a year. ... There is a chance that the data of ionospheric plasma observations hold an answer to the latter question. Satellites and ground-based facilities may detect earthquake precursors in the ionosphere a few hours or days before the main shock. ... ULF "Hz"-oscillations have been recorded several hours before the main shock in a narrow magnetic field tube (40...100 km along the satellite trajectory) conjugated with epicenter of the earthquake. ...

Pulkovo Database of Observations of Visual Double Stars . ... Catalog of relative positions of visual double stars, based on photographic observations performed since 1960 in Pulkovo on the 26-inch refractor (A.A.Kiselev, O.A.Kalinichenko, O.V.Kiyaeva, N.A.Shakht, L.G.Romanenko, I.S.Izmailov, O.P.Bykov, K.L.Maslennikov, E.A.Grosheva, D.L.Gorshanov), 2010 . ... Enter either ADS or WDS number. Click here to display full list of visual double stars observed at Pulkovo. ADS . ...

... The extinction in terrestrial atmosphere. ... A star was observed at different zenith distances during one night at the Engelgardt's Astronomical Observatory in the program of atmospheric extinction study at blue. ... Calculate the air mass for given zenith distances in 1st 54.9 11800 column, and write the result into the 2nd column. ... Spectral observations. ... Calculate the radial velocity Vr of the star on each date, the results of measurements and write calculations into the table. ...

Next: The Photometric Performance of Up: NICMOS Data Calibration and Previous: Status and Goals of . ... Absolute Spectrophotometric Standards . Absolute Photometry . ... Velocity shifts and Photometry with Narrow-band Filters . ... HST, NICMOS, near-infrared, standards, photometry, calibration . ... In practice NICMOS does not have a set of filters matching any of the standard ground-based photometric bands and this poses a challenge when trying to achieve precise absolute photometry. ...

... ON THE ROLE OF LARGE-SCALE PLASMA IRREGULARITIES AT THE FINAL STAGE OF ANOMALOUS ABSOPTION DEVELOPING UNDER HF HEATING OF THE IONOSPHERE . ... Fig. ... With the aid of numerical statistical modeling based on multiple ray tracing it is shown that in presence of large-scale irregularities the reflected signal amplitude mean value is increased significantly. ... Dependence of the mean amplitude of the reflected from the ionosphere signal on the large-scale (10-50 km) electron density irregularity level...

... Green and blue curves - CYGAM telescope (squares - no constraints on the angle a , triangles - a <0.5 0 ); red curve - EGRET telescope. Effective area versus photon incidence angle to relative the longitudinal telescope axis (squares - no constraints on the angle a , triangles - a <0.5 0 , spectral index g= 2). ... Angular resolution for normal to the axis X incidence versus source power law spectrum index (squares- no constraints on the angle a , triangles- a <0,5 0 ). ... CYGAM (PDF, 450 Kb) . ...

... About ATMoB . ... The Observing Committee is starting an Observing Awards Program to promote observing among the membership of the Amateur Telescope Makers of Boston. ... Participant must be a current member of the Amateur Telescope Makers of Boston . ... To qualify for your Observing Award Certificate, turn in your worksheet and drawings to an ATMoB Observing Committee member or observing@atmob.org . ... This Excel sheet has useful macros. ... Copyright (c) Amateur Telescope Makers of Boston, Inc. ...

Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 02 - 08.02.2015, Forecast on 09 - 16.02.2015, Carrington Rotation 2160 (1,28.02.2015) SUNSPOT-FORMING ACTIVITY OF THE SUN REMAINED AT THE MIDDLE LEVEL ALL DAYS. ... NEXT WEEK EXPECTED THE AVERAGE LEVEL OF SUNSPOT ACTIVITY. ... FLARE ACTIVITY WAS AT THE MODERATE LEVEL ON 04.02, AND THE LOW ON OTHER DAYS. ... BY DATA OF CORONOGRAPHS SOHO AND STEREO WERE OBSERVED > 21 CME. NO EARTH-DIRECTED CME WERE OBSERVED THROUGHOUT THE PERIOD. ...

... A document window is shown, with 8 lines (numbered 1 to 8), each 24px high. The text of the "outer" box (at the end of line 1, halfway into line 2, and halfway into line 3) is shifted upward 12px. The text of the "inner" box, thought shifted upward as well, has been relatively positioned so that it lies in its normal flow position at the end of line 2. ... The lines, as they appear in the image, contain: Start 1 Beginning of body contents. 2 of outer contents. Inner contents. ...

... We publish 16 Doppler imaging temperature maps for the years 1994-2002 of the active RS CVn star II Peg. ... Through Doppler imaging we want to study the spot evolution of the star and in particular compare this with previous results showing a cyclic spot behaviour and persistent active longitudes. ... The derived temperature maps are quite similar to the ones obtained earlier with a different methods, the main differences occurring in the spot latitudes and relative strength of the spot structures....

Twilight observations with MASS/DIMM B. Safonov Sternberg Astronomical Institute Moscow State University Comprehensive Characterization of Astronomical Sites, 2010 B. Safonov (Moscow State University) Twilight observations with MASS/DIMM SITE 2010 1 / 17 Why observe in twilight with MASS/DIMM? ... ASM includes 3 devices sensitive to background: guider, DIMM and MASS. B. Safonov (Moscow State University) Twilight observations with MASS/DIMM SITE 2010 2 / 17 Background in guider. ...

... Contacts . 2012: . ... We refined the fundamental parameters of the components, the orbital periods, and the conditions of photospheric heating of the secondary component by the ultraviolet radiation of the hot component. ... The observations of the star clusters associated with ultra-luminous x-ray sources (ULXs) in four galaxies on the 6-meter and VLT telescopes have shown that all the ULXs are located within 200pc of very young star clusters (younger than 5 million years). ... Archive . ...

... GCR and SCR are primary cosmic rays. 10-15 years after the discovery of cosmic radiation (1919) there emerged two main avenues of investigation in the physics of cosmic rays (CR): 1) nuclear - elucidation of the origin of elementary particles and nuclear interactions; and 2) astrophysical (space physics) - solution of the problem related to the origin and variations (changes in intensity) of CR. ... Besides, the CR flux in interplanetary space is, strictly speaking, not isotropic. ...

... 8, ``Celestial Mechanics'', 2002 Estimation of masses of some minor planets from observations of perturbed bodies O. M. Kochetova Institute of Applied Astronomy, St. Petersburg, Russia The most straightforward method of mass determination of minor planets is the dynamical one which uses the gravitational perturbations produced by minor planet in the motion of other bodies. ... The values of the masses of minor planets (15), (29) and (65) appear to be rather close in both papers. ...

GRANAT is the Russian x-ray sattelite launched to the high apogee orbit (200,000 km) and operated almost for 10 years (1989 -1999) , carrying out four major instruments: French SIGMA coded-mask hard x-ray telescope (30-1000 keV), Soviet ART-P coded-mask telescope (2??-60?? keV), all-sky monitor WATCH (6-150 keV), and a gamma-burst detector PHEBUS . ... Since September 1994, GRANAT is in the survey mode. ... Explore pages devoted to individual GRANAT instruments (including main scientific results): . ...

... The cosmic cloud of gas and dust is W33, a massive starforming complex some 13,000 light-years distant, near the plane of our Milky Way Galaxy. ... This time lapse composite image follows all four launches of the small, multi-stage rockets to explore winter's mesmerizing, aurora-filled skies. ... Light from Cygnus A . ... Celebrating astronomy in this International Year of Light, the detailed image reveals spectacular active galaxy Cygnus A in light across the electromagnetic spectrum. ... January ....