NGC 6188

I imaged the magnificent emission nebula NGC 6188 twice over the years, both times during stays at the Tivoli astrofarm in Namibia. My first image was captured in 2008 using my DSLR equipment, taking advantage of the exceptionally dark southern skies to record the extensive nebular complex. Fourteen years later, in 2022, I revisited the object using the equipment of a rented observatory at Tivoli. The modern imaging system, combined with improved acquisition and processing techniques, revealed significantly finer detail within the glowing hydrogen clouds and intricate dust structures. Comparing the two images illustrates both the advances in astrophotographic technology and my own progress over the years.

NGC 6188 is located in the constellation Ara at a distance of approximately 4,000 light-years. It is one of the most spectacular emission nebulae in the southern Milky Way and forms part of a vast complex of ionized gas and dust surrounding the young open cluster NGC 6193. The energetic ultraviolet radiation emitted by the cluster’s hot O-type stars ionizes the surrounding hydrogen gas, causing the nebula to glow predominantly in the Hα emission line.

The nebula is famous for its dramatic appearance, featuring towering dark dust clouds, bright emission ridges, and intricate filamentary structures. These features are shaped by intense stellar winds and radiation from the massive stars of NGC 6193, which continuously sculpt the surrounding molecular cloud. The interaction between radiation and dense interstellar material creates spectacular pillars, cavities, and bright ionization fronts, making NGC 6188 an outstanding target for both professional astronomers and astrophotographers.

Embedded within the nebula are numerous Bok globules and dense molecular condensations where new generations of stars are forming. These dark clouds are protected from the harsh ultraviolet radiation and represent the earliest stages of stellar birth. Consequently, NGC 6188 is an active stellar nursery, offering astronomers valuable insight into the processes of massive star formation and the interaction between young stars and their natal environment.

One of the most remarkable features of the region is the close relationship between NGC 6188 and the rare NGC 6164, located nearby on the sky. Together they illustrate two very different aspects of the life cycles of massive stars: while NGC 6188 is dominated by ongoing star formation, NGC 6164 represents material ejected by an evolved massive star.

The images obtained in 2008 and 2022 beautifully demonstrate the evolution of both imaging technology and processing techniques. The early DSLR image already captured the grandeur of this remarkable nebula, while the more recent observatory dataset reveals an extraordinary wealth of fine structures, delicate dust filaments, and subtle variations within the glowing gas. Together, the two images showcase one of the finest star-forming regions in the southern sky and highlight the dynamic processes that continue to shape our Galaxy.

For the 2022 data the calibration and registration and the final processing was done with PixInsight. The result was as follows:

The images were taken with the following equipment:

Date: 04/30/2022 to 05/03/2022
Location: Tivoli, Namibia
Telescope/Lens: ASA 16″ Astrograph
Focal length [mm]: 1440
Focal ratio: 3.6
Mount: ASA DDM85
Camera: Moravian G4 16000
Filter: Hα:[OIII]:R:G:B
Exposure time [min]: 190:150:50:50:50
Resolution: 1.29″/px

For the 2008 data the calibration and registration was done with DeepSkyStacker and the final processing was done with PixInsight. The result was as follows: