This object is a supernova remnant (SNR) located 800 light years away in the southern constellation of Vela at a declination of -46 degrees.   This 6 panel RASA mosaic covers 30 square degrees, which is an area 100 times larger than the full moon to our apparent view.   The individual images were captured at elevations ranging from 7 to 13 degrees above my southern horizon.

I have dreamed of imaging the entire Vela SNR since reading about it many years ago.  I never thought that I could achieve that dream from my backyard location.  I have imaged many parts of it individually, piece by piece, over the years, as shown in my Astrobin Vela SNR collection.  Now, with the light gathering and wide FOV of my new RASA setup, I have finally been able to capture the whole Vela SNR.

Based on expansion calculations and distance measurements, the supernova is believed to have occurred about 10,000 years ago, so bright that it was visible by naked eye during the daytime.  It must have been quite a sight and a wonder to behold for the inhabitants of earth at that time.  The SNR has now expanded to a diameter of 100 light years.

Although at first glance both hydrogen and oxygen are seen throughout the image, careful study will reveal that the detail of the SNR, and especially the filaments, are primarily defined by the oxygen gas fronts.

In the book Imaging the Southern Sky, authors Chadwick and Cooper describe that, while looking at this object through a telescope, one gets the feeling of traveling along a wide open highway.  The terms for the various parts of the SNR are from that book and relate to the highway analogy (see mouseover titles in orange color).  The feature list below starts at the top of the image (north) and moves clockwise around the SNR:

• The Crest – This part of the SNR is at the northern “top” of the SNR, although my southern hemisphere friends will feel differently about that (perhaps it is then the “trough”?).  It lies just north of the bright magnitude 4 star e Velorum.
• The Bridge – This is the brightest section of the SNR and consists of curving filaments in an incredibly long line, looking like a multi-spanned bridge.
• The Highway – This section continues from the Bridge but in a straighter section.  This is the section where the hydrogen filaments are most prominent.
• The Spur – Parallel to the Highway, the spur is the thinnest and whitest section of the SNR.
• The Double Roundabouts - This feature was not highlighted in the book at all so I named it myself.  These are the only SNR features which are circular instead of arcs.  I like the similarities between the 2 circles and I am curious about how they were formed.
• The Bypass – Running north-south right down the middle of the image, this is the longest straight section of the SNR and consists almost entirely of oxygen signal.
• The Twin Crescents – These two arc shapes stand alone in a wide region and are close to the lovely NGC 2659 open star cluster.
• The Spiral Flame -  This wonderful twisting set of filaments (the "Spiral") is the most interesting part of the SNR in my opinion.  Gum 18 provides a nice reddish color contrast (the "Flame") to the oxygen-only filaments of the Spiral.

The Vela Pulsar, identified in purple text in the mouseover, is not optically visible at 24 magnitude.  It is the brightest persistent object in the high-energy gamma-ray sky.  It is believed that the pulsar was the original source of the SNR, but its off-center location and its lack of much proper motion has led some to question whether it is the source. 

My image does not include several components of the Vela SNR which have been described as “explosive fragments” that now lie outside of the SNR shock-wave boundary.  NGC 2736, nicknamed Herschel’s Ray and the Pencil Nebula, is just off image to the lower left.  Similarly, Puppis A is just off image to the upper right.

3 small open star clusters are seen on the image and identified on the mouseover – NGC 2645, NGC 2659, and NGC 2660. In addition, 4 Gum HII nebulae and 1 planetary nebula (Kohoutek 2-15) are also identified.  Other smaller and fainter clusters and nebulae are scattered throughout the image.