Lagoon, Trifid, Eagle, Swan, and Milky Way Center HaRGB Mosaic
Lagoon, Trifid, Eagle, Swan, and Milky Way Center HaRGB Mosaic
Lagoon, Trifid, Eagle, Swan, and Milky Way Center HaRGB Mosaic
The constellations of Sagittarius and Serpens contain some of the densest and most beautiful regions of our Milky Way Galaxy. Highlighted in this four panel mosaic covering 11 by 15 degrees of sky are four of the grand nebulae catalogued by Charles Messier. At the top of this image is M16, the Eagle Nebula. A region of star development, the nebula is widely known for the Pillars of Creation which were made famous by the iconic Hubble Telescope photograph.

Below the Eagle Nebula is M17, the Swan Nebula. This nebula is also known as the Omega Nebula, Lobster Nebula, and Check Mark Nebula.

Towards the bottom of the mosaic is the combination emission and reflection nebula M20, more commonly known as the Trifid Nebula. The name comes from the trisected emission nebula at the bottom. The blue reflection nebula above it is actually behind the emission portion of the nebula. The dust in this part of the nebula reflects light from the hot blue star, thereby giving it a beautiful azure color.

Below the Trifid Nebula is the largest nebula in the image, M8, the Lagoon Nebula. In addition to the extensive Ha regions throughout the nebula, M8 features numerous Bok globules - dark areas of the nebula where protostars are condensing from the gas and dust.

In this image, North is up.

Exposure Details
Lens Canon EF 200mm f/2.8L II USM, Celestron C-8 for detail images
Focal Length 200mm for base image, 1160mm for M8, M20, M16 and M17 detail images
Focal Ratio f/3.5 for 200mm images
Mount Schaefer GEM - 7 1/2 inch Byers gear
Guiding ONAG On-Axis Guider via C-8, Lodestar autoguider, PHD Guiding
Camera Hutech modified Canon 6D
Exposure 128 x 600 sec of RGB subexposures @ ISO 200 (21.3 hours) plus 116 x 600 sec (19.3) Ha exposures w/6nm Astronomik clip filter at ISO 1600 - total 40.6 hours
Calibration 30 darks, 30 flats, 30 bias
Date June 28, 29, 30; July 1, 22, 24, 26, and 31 and August 1, 2014
Temperature Typically 64F to 69F
SQM Reading Typically 21.35 to 21.50 (Bortle 4)
Seeing 2/5 on 7/31; 3/5 on 6/28, 6/30, 7/26; 4/5 on 6/29, 7/1, 7/22, and 8/1
Location Pine Mountain Club, California
Software Used Images Plus 5.75 for camera control. Images Plus 6.0 for calibration, stacking, digital development, feature mask, star shrinking and halo reduction, smoothing and noise reduction. Photoshop CS5 used for levels and curves, hue and saturation colorizing and adjustments, lens correction, cropping and selective color. Pixinsight 1.8 for additional stretching. HLVG for additional color correction, Gradient Xterminator for gradient removal. Carboni Tools for additional noise reduction and smoothing, Focus Magic for focus restoration. Registar for stack alignment.
Notes This was a tricky mosaic for me to put together. The area is so dense with stars that keeping them to some reasonably well managed level was difficult. Ultimately, I'm pretty happy with the final result, although it took me almost a year to put it all together!