SH2-158 is also known as the Northern Lagoon Nebula or NGC 7538. It is an active star-forming H II region in the constellation Cepheus. This nebula is located about 9,100 light-years away. It is home to massive young stars and protostars. It includes one exceptionally large O-type protostar. It is part of the Cassiopeia OB2 complex in the Perseus Arm of the Milky Way.
Sh2-158 is often overlooked by amateur astrophotographers due to its proximity to the larger and more famous Bubble Nebula. However, it is a challenging and rewarding target. I was intrigued by the name alone. I have imaged the Lagoon Nebula and hadn’t heard of the Northern Lagoon Nebula. A quick search led to a few examples but not many, so I set my sights on the target.
Sh2-158 is an active star-forming region embedded within a large molecular cloud. As an emission nebula, Sh2-158 glows. However, its light is spread out over a large area. This distribution makes its surface brightness very low. Long total exposure times are needed. Often, multiple hours are required to gather enough light. These times help distinguish the nebula from the sky’s background noise. The surrounding dust clouds absorb and scatter light, further diminishing the nebula’s brightness and obscuring fine details within it. This makes revealing the nebula’s structure challenging and requires advanced processing techniques. The dust also causes reddening, altering the color balance of images and requiring careful calibration during post-processing.
Image acquisition details in astrobin image
I imaged it over the course of three nights in Sept 2025. I used a RC8 telescope at 1625 mm paired with an AI071MC camera atop an Eq6r Pro mount. I used a Radian Ultra Quadband filter.
