... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. November 28, 1998 . A Lonely Neutron Star . ... Explanation: How massive can a star get without imploding into a black hole? ... Assuming that the object is a neutron star of typical mass, some previous theories of neutron star structure would have predicted an implosion that would have created a black hole . ... About APOD > . ...

... Assured of a reliable method of solving the normal equations, we now consider the equations of condition. The observed magnitude m of a star at M air masses with true instrumental magnitude is modelled as ([ 10 ], [ 28 ]) . ... The effective extinction coefficient depends on the effective spectral gradient [ 29 ] of the star, for which we use some color index, affected by half the atmospheric reddening ([ 26 ], [ 10 ]): . ... Thus, for the B band of UBV, we use the (U-V) color. ...

... CIMAFITS is the name for the Arecibo FITS-file format. ... This is a list of (fairly) up-to-date documents describing CIMA and CIMAFITS: . The CIMA version history log which is the most up-to-date page listing all changes made to the different versions of CIMA . ... The CIMA user's log which chronologically lists changes made to CIMA that may be relevant to an observer. The CIMA engineering log which lists engineering changes made to CIMA that probably are of less interest to an observer. ...

... ESO, the European Southern Observatory . ... Travel and Contacts . ... Green ESO . ... Survey Telescopes . ... 2002 . ... Images of Titan taken on November 26, 2002 through nine different filters to probe different altitudes, ranging from the stratosphere to the surface. ... Due to these good observing conditions, Titan's trailing hemisphere was observed with contrasts of about 40%, allowing the detection of several bright features on this surface region, once thought to be quite dark and...

... Let us first find out which way -- rise in spectral resolution with some loss in the S/N ratio or increase in the S/N ratio with a fixed spectral resolution -- is better for the purpose of reduction of equivalent width determination errors. ... N -- number of counts for 1 ? ... line equivalent width, . ... Thus if the spectral resolution is managed to be increased (i.e. to decrease )without loss in the number of counts falling at 1 ?, the equivalent width measurement error is then proportional to . ...