The Bubble, Cave, Lobster, and More in HaRGB
The Bubble, Cave, Lobster, and More in HaRGB
The Bubble, Cave, Lobster, and More in HaRGB
The constellations of Cassiopeia the Queen and Cepheus the King are filled with beautiful regions of Hydrogen gas (HII regions) and clusters of stars. In this image, the bright HII nebula at the top (slightly right of center) is Sh2-157 and is known as the Lobster Claw Nebula. In the lower left corner of the Lobster Claw Nebula is the open star cluster, NGC 7510. To the right and below Sh2-157 is NGC 7635, the Bubble Nebula. Although rather small in this wide field photo, close inspection of the high resolution version will reveal the bubble like feature that inspires its name. Down and to the right of the Bubble Nebula is the bright star cluster, M52. This beautiful cluster contains about 200 stars.

The small bright nebula to the left of M52 is NGC 7538 (at 4 o'clock, close to the center of the image). The fairly bright nebula in the lower left of the image is Sh2-155, the Cave Nebula. The fainter nebula at 9 o'clock in the image is Sh2-154, while the cluster immediately above it is NGC 7419.

The objects in this image can also be seen in the Annotated Version. The Hydrogen Alpha Only Version of the image shows the distribution of the Ha nebulae in this field of view.

In this image, North is down.

Exposure Details
Lens Canon EF 200mm f/2.8L II USM
Focal Length 200mm
Focal Ratio f/3.5
Mount Schaefer GEM - 7 1/2 inch Byers gear
Guiding ONAG On-Axis Guider, Lodestar autoguider, PHD Guiding
Camera Canon 450D - Gary Honis modified
Exposure 92 subs of 300 sec each @ ISO 400 (7 2/3 hours) plus 92 subs of 600 sec @ ISO 1600 (15 1/3 hours) using Astronomik 6nm Ha clip filter - 23 hours total
Calibration 30 darks, 30 flats, 30 flat darks, 30 bias
Date October 7, November 8, 10, and 30, 2013
Temperature 10/7-48F 11/8-50F, 11/10-52F, 11/30-39F
SQM Reading 10/7 - 21.25 (Bortle 4),11/8-20.8 (Bortle 4.5), 11/10-20.7 (Bortle 4.5), 11/30-21.3 (Bortle 4)
Seeing 10/7 - 3/5, 11/8 and 11/10 - 5/5, 11/30 - 3/5
Location Pine Mountain Club, California
Software Used Images Plus 5.75 for camera control, calibration, stacking, digital development, feature mask, smoothing and noise reduction, and multiresolution sharpening. Photoshop CS5 used for levels and curves, high pass filter, screen mask invert, selective color, hue and saturation colorizing, and unsharp mask. Gradient Xterminator for gradient removal. HLVG for color correction. Registar for aligning and registering stacks. Carboni Tools for additional noise reduction, and smoothing. Focus Magic for focus restoration.
Notes There are so many varied objects in this image that I found it quite challenging to combine the Ha and RGB and maintain fairly clean colors. Ultimately, I'm quite pleased with the final image, as it contains some nice detail and some overall good color.