Conquering Light Pollution: Capturing the Milky Way Under Bortle 9 Skies

Astrophotography is often associated with dark, remote locations, far from the glare of urban centers. But what happens when the urge to capture the cosmos strikes from a place with extreme light pollution, like a Bortle 9 zone? Today, we're diving into a remarkable achievement by astrophotographer DougBR80, who managed to capture the Milky Way from São Paulo, Brazil.

The Challenge: Bortle 9 Skies

São Paulo, Brazil, is known for its intense light pollution, placing it firmly in the Bortle 9 category – the highest level of sky brightness. For most astrophotographers, this would be an insurmountable obstacle, rendering faint deep-sky objects like the Milky Way completely invisible. However, DougBR80 proved that with the right equipment and a significant amount of dedication to processing, even these challenging conditions can yield impressive results.

The Gear and Setup

DougBR80 utilized a modified Canon t2i camera, a popular choice for astrophotography due to its sensor capabilities. The lens used was an 18mm f4 lens, offering a wide field of view perfect for capturing large swathes of the night sky.

For the acquisition, the following parameters were employed:

Lights: 37 frames
Darks: 12 frames
Exposure: 13 seconds per frame
ISO: 1600

Interestingly, when questioned about calibration frames, DougBR80 confirmed that flats and bias frames were not used. This is a departure from standard astrophotography practice, which typically emphasizes the importance of these frames for removing artifacts and ensuring consistent data. It highlights the reliance on post-processing to overcome data limitations.

The Processing Pipeline

Achieving a clear and detailed image of the Milky Way from a Bortle 9 sky requires intensive post-processing. DougBR80 employed a powerful software suite to bring out the faint details:

Siril: Often used for stacking and initial calibration (even without explicit calibration frames, stacking algorithms can help reduce noise).
StarNet: Essential for removing stars, allowing for more focused processing of the nebulae and galactic core.
Graxpert: A tool known for its excellent noise reduction and detail enhancement capabilities, crucial for extracting signal from noisy data.
Adobe Lightroom: Used for final color correction, contrast adjustments, and overall polishing of the image.

The Result

The outcome of this meticulous process is a truly impressive image, demonstrating that even under the most challenging light-polluted skies, the beauty of the Milky Way can still be revealed. The comments section of the original post is filled with praise, with many expressing surprise and admiration for the results achieved without any specific light pollution filters, relying solely on the modified camera and extensive processing.

This image serves as an inspiration to astrophotographers facing similar light-polluted environments, proving that dedication, knowledge of processing techniques, and a bit of innovation can help overcome significant hurdles.