Lagoon and Trifid Nebulae in HaRGB: A Celestial Spectacle from Down Under

Perth, Western Australia, has seen its fair share of challenging weather this past winter. But for dedicated astrophotographers, persistence pays off. This incredible HaRGB image of the Lagoon and Trifid Nebulae is a testament to that perseverance, representing a colossal effort of nearly 33 hours of total integration time, spread across three months of dodging clouds and rain.

These majestic nebulae, located approximately 4,000 light-years away, are vibrant HII emission nebulae, regions of ionized hydrogen gas where new stars are born. The combination of Hydrogen-alpha (Ha) and RGB data in this image brings out the intricate details and rich colors of these celestial wonders.

This project also marks a significant upgrade in equipment, showcasing the new Sky-Watcher Wave 150i mount. The astronomer reports a noticeable improvement in guiding performance compared to their previous mount, which is crucial for achieving sharp, detailed images of faint deep-sky objects.

Equipment Used:

• Telescope: William Optics RedCat51
• Mount: Sky-Watcher Wave 150i Strain Wave
• Imaging Camera: ZWO ASI294MM Pro @ -10C, 121 Gain, Bin 2
• Guide Camera: ZWO ASI290MM Mini + ZWO OAG
• Filters: Astronomik Ha 6nm, Antila RGB

Acquisition Details:

• Hydrogen-alpha (Ha): 36 x 600s
• Blue: 265 x 120s
• Green: 268 x 120s
• Red: 271 x 120s

Processing Workflow (PixInsight):

1. Calibration and Stacking: Performed using the Weighted Batch Processing (WBPP) script.
2. Gradient Correction: Addressing any unwanted background gradients.
3. Noise Reduction and Detail Enhancement: Utilizing BlurXTerminator, StarXTerminator, and NoiseXTerminator on the Ha channel.
4. Color Integration: Channel Combination for RGB data.
5. Color Calibration: SPCC for accurate color adjustments.
6. Stretching: GeneralizedHyperbolicStretch to bring the image to a non-linear state, followed by STF + Histogram for stretching the Ha channel.
7. HaRGB Combination: Merging the Ha and RGB data for enhanced detail and color.
8. Final Adjustments: Curves for saturation and RGB/K levels.
9. Star Reintegration: Using PixelMath to re-add stars.
10. Cropping and Resizing: DynamicCrop followed by IntegerResample x2 for publication.

This image is a beautiful example of what can be achieved with dedication, the right equipment, and meticulous processing. The result is a captivating view of two of the night sky's most iconic nebulae.