============================================================================= A basic set of bright stars -- taken from the xephem program. Based on the 5th Revised edition of the Yale Bright Star Catalog, 1991, from ftp://adc.gsfc.nasa.gov/pub/adc/archives/catalogs/5/5050. Only those entries with a Bayer and/or Flamsteed number are retained here. Format: Constellation BayerN-Flamsteed, as available. Bayer is truncated as requried to enforce a maximum total length of 13 imposed within xephem. Common names were then overlayed by closest position match from hand-edited a list supplied by Robert Tidd (inp@violet.berkeley.edu) and Alan Paeth (awpaeth@watcgl.waterloo.edu) ============================================================================= Data file format: name , right assention (radians) , declination (radians) , magnitude (0.0 - 1.0) ============================================================================= The following information is taken from: http://www.lclark.edu/~wstone/skytour/celest.html Please visit the above site, it contains much more complete information. CELESTIAL MEASUREMENTS RIGHT ASCENSION AND DECLINATION Although we know that the objects we see in the sky are of different sizes and at different distances from us, it is convenient to visualize all the objects as being attached to an imaginary sphere surrounding the Earth. From our vantage point, the sky certainly looks like a dome (the half of the celestial sphere above our local horizon). The celestial sphere is mapped in Right Ascension (RA) and Declination (Dec). Declination is the celestial equivalent of latitude, and is simply the Earth's latitude lines projected onto the celestial sphere. A star that can be directly overhead as seen from the Earth's Equator (0 degrees latitude) is said to be on the Celestial Equator, and has a declination of 0 degrees . The North Star, Polaris, is very nearly overhead as seen from the North Pole (90 degrees North latitude). The point directly over the North Pole on the celestial sphere is called the North Celestial Pole, and has a declination of +90 degrees . Northern declinations are given positive signs, and southern declinations are given negative signs. So, the South Celestial Pole has a declination of -90 degrees . Right Ascension is the equivalent of longitude, but since the Earth rotates with respect to the celestial sphere we cannot simply use the Greenwich Meridian as 0 degrees RA. Instead, we set the zero point as the place on the celestial sphere where the Sun crosses the Celestial Equator (0 degrees Dec) at the vernal (spring) equinox. The arc of the celestial sphere from the North Celestial Pole through this point to the South Celestial Pole is designated as Zero hours RA. Right Ascension increases eastward, and the sky is divided up into 24 hours. This designation is convenient because it represents the sidereal day, the time it takes for the Earth to make one rotation relative to the celestial sphere. If you pointed a telescope (with no motor drive) at the coordinates (RA=0h, Dec=0 degrees ), and came back one hour later, the telescope would then be pointing at (RA=1h, Dec=0 degrees ). Because the Earth's revolution around the Sun also contributes to the apparent motion of the stars, the day we keep time by (the solar day) is about four minutes longer than the sidereal day. So, if you pointed a telescope at (RA=0h, Dec=0 degrees ) and came back 24 hours later, the telescope would now be pointing at (RA=0h 4m, Dec=0 degrees). A consequence is that the fixed stars appear to rise about four minutes earlier each day. ============================================================================= From: steve@mred.bgm.link.com (Steve Baker) Subject: Re: FG: Fun in the sun ... Date: Tue, 5 Aug 97 15:37:27 -0500 You probably ought to get the stars right too - there is a database of the 300 brightest stars in the 'Yale Bright Star Catalog' - which I enclose below. I'd guess that you could navigate by the stars - so this might not be a completely useless feature - right? Anyway, if all else fails - and the flight sim never gets going - we could at least sell this as a planetarium :-) The format of the star data is: Name Right-Ascension Declination Magnitude (Ascension and Declination are in radians) We took the magnitude value, scaled it by 0.8 and added 0.2 to make a 0->1 brightness value. Using the raw data created too many very dark stars. Originally, there were constellation names as sub-headings - but I think I deleted them to make the file easier to parse :-) That makes the 'name' field pretty pointless. if you are still talking about the geocentric coordinate system where the terrain is modelled with Z pointing towards the North pole, X out of the 0 degree meridian at the equator and Y out at the Indian ocean at the equator - then you can position the stars using: star[ X ] = fsin ( ra ) * fcos( decl ) ; star[ Y ] = fcos ( ra ) * fcos( decl ) ; star[ Z ] = fsin ( decl ) ; (which you can precompute at startup) ...and then rotate them about the Z axis using GMT*two_pi/24.0 # Put them all in a display list - use GL_POINTS as the primitive... glNewList ( ...whatever... ) glBegin ( GL_POINTS ) ; for ( int i = 0 ; i < num_stars ; i++ ) { glColor3f ( star_brightness[i], star_brightness[i], star_brightness[i] ) ; glVertex3f ( star_x[i], star_y[i], star_z[i] ) ; } glEnd () ; glEndList () ; You need to draw them out by the far clip plane so they don't occult anything. Then you need to translate them using the same x/y/z as the eyepoint so that you can never fly any closer to them.