Antares Region in Scorpio and Ophiucus 


Copyright 2007 Hap Griffin

One of the most colorful regions in the sky...the area around the bright star Antares in the constellation of Sagittarius.  While this region appears to be busy and chaotic, it is actually quite spread out in three dimensions with each object being at a different distance from us.  The bright orange star at the lower left is Antares...a class M supergiant.  It is 700 times the diameter of our sun...if it were placed at the center of our solar system, it's outer edges would lie between the current orbits of Mars and Jupiter.  It shines with a total light output of 65,000 times that of our sun.  Antares lies at a distance of 604 light-years and its intense radiation illuminates the nebulosity surrounding it.  This is one of the very few instances of an orange nebula anywhere in the sky.  To the lower right is globular star cluster M4...a grouping of thousands of stars in an area only 75 light-years in diameter and lying at a distance of 7200 light-years.  Just above and to the right of Antares is another globular star cluster, NGC 6144, at a much greater distance of 28,000 light-years.  The two blue reflection nebulae, IC 4605 at the middle left and the Rho Ophiuci nebula near the top, demonstrate how hydrogen gas when reflecting light from embedded stars glows blue.  The opposite occurs in emission nebulae, such as the one surrounding the bright star at the right side of the frame, where the hydrogen is excited into fluorescing and glows red.   The dark grayish blue area in the middle that resembles an Iris is IC 4603.  The very dark region that starts near the center and exits the photo to the left is not just a region lacking's a huge cloud of dense, dark dust that obscures our view of the stars beyond.  As it leaves this region to the east, it covers an area many times the extent of this frame.


Date/Location:    May 14, 2007     Griffin/Hunter Observatory    Bethune, SC
Instrument:    Canon 350XT Digital SLR (modified) through Nikon 300mm F/4.5 lens 
Focal Ratio:   F/4.5
Guiding:    None - piggybacked on Meade RCX-400 telescope
Conditions:    Visually clear
Weather:    60 F
Exposure: 219 minutes total (73 x 3 minutes)
Filters:    Baader UV/IR Block
Processing:    Focused and captured with DSLRFocus.  RAW to TIFF conversion, auto-dark and flat frame calibration, Digital Development, Richardson-Lucy deconvolution, resizing and JPEG conversion in ImagesPlus.  Color correction in Photoshop CS2.