Capturing the Fireworks Galaxy: A Bortle 8/9 Astrophotography Triumph

Even under the challenging skies of a Bortle 8/9 location, just 10km from downtown Lisbon, Portugal, breathtaking deep-sky objects can be revealed. This remarkable image of the Fireworks Galaxy (NGC 6946) is a testament to the capabilities of modern astrophotography equipment and meticulous processing.

The Target: NGC 6946

The Fireworks Galaxy, also known as NGC 6946, is an intermediate spiral galaxy. It's aptly named for the numerous supernovae that have been observed within it, making it a dynamic and exciting target for astronomers and astrophotographers alike. Despite its relative proximity to Earth, capturing its intricate details can be a challenge, especially when battling significant light pollution.

The Gear and Setup

This stunning capture was made possible by a carefully selected suite of equipment:

• Telescope: TS optics 8” F5 Newtonian (1000mm) – A powerful Newtonian reflector providing excellent light-gathering capabilities.
• Camera: ZWO ASI585MC – A sensitive color astronomy camera.
• Filter: Optolong L-pro2 filter – Crucial for cutting through light pollution and isolating specific wavelengths of light.
• Mount & Control: ZWO AM5n Skytracker with a 1.75" steel tripod and ZWO 160mm pier extension, controlled by a ZWO AsioAir Plus – Ensuring stable tracking for long exposures.

The Acquisition Process

The image represents a single night's integration of 180 x 60-second exposures. To ensure the highest quality data, the acquisition also included calibration frames: 30 flats, 60 bias frames, and 30 dark frames. These calibration frames are essential for removing noise, sensor artifacts, and vignetting from the final image.

Processing and Enhancement

The raw data was expertly stacked and processed using PixInsight, a powerful software suite favored by many advanced astrophotographers. Following the initial stacking and noise reduction, the image was further enhanced and cropped in Pixelmator Pro to bring out the stunning details of the Fireworks Galaxy.

A keen observer might notice the characteristic 'crosses' on the brighter stars. These are known as diffraction spikes, a natural phenomenon in Newtonian telescopes caused by the spider vanes that hold the secondary mirror. They are a signature of this type of optical design and add a unique aesthetic to the final image, especially on brighter stars.

This image is a fantastic example of what can be achieved with dedicated effort and the right tools, even when facing the hurdles of urban skyglow. It's a beautiful reminder of the wonders that await us in the cosmos, visible even from our own backyards with the right approach.

Reading Time: 3 min read