NGC 3628 (The Hamburger Galaxy) in LRGB-Ha

Spring evenings and nights are adorned by the Hamburger galaxy in Leo, a zodiacal constellation. It is a spiral galaxy, but it faces us exactly from the side, so the spiral shape of the galactic arms is not visible. The galaxy can be observed with a small telescope, but the beautiful colourful structure of the galaxy can only be seen in photographs with long exposure times. Relative to our observation site, the Hamburger galaxy is receding at a speed of over 840 km/s (522 mi/s), which is about 0.28 % of the speed of light. The distance to the galaxy is 35 million light years or about 330.000.000.000.000.000.000 km. ✨

From the side, the galaxy has stretched and rounded square shape. In the galactic plane, a dark band of dust extends down the middle, which spreads out towards the ends of the galaxy, resembling on an elongated letter X. Some people see the galaxy as a hamburger- or even peanuts-shaped object. 😊 Recent research has revealed that the unique side-shape of the Hamburger galaxy is the result of gravitational influences from nearby satellite galaxies and other galaxies in the neighborhood. Gravitational influences have also formed an unusual 300,000-light-year-long galactic tail, the beginning of which can be seen in the left part of the image.

I took the photo of the Hamburger galaxy using the Sky Watcher Esprit 120ED APO @ 840 mm (f/7) refractor telescope, and the QHY268M cooled monochrome camera. The total exposure time was 12 h 33 min. The image was processed in the L_RGB_Ha technique. ✨

Equipment and acquisition details:

• Main object: Hamburger galaxy (NGC 3628)
• Imaging telescope: Sky Watcher Esprit 120ED APO at focal length 840 mm (f/7) with field corrector Sky Watcher 1.0 x
• Imaging camera: QHY268M cooled monochrome camera in High gain mode (mode 1), gain 56, offset 20, sensors temperature -15 °C, USB speed 45
• Imaging scale: 0.9 arcsec/pixel
• Guiding telescope: Svbony 50 mm (190 mm) @ f/3.9
• Guiding camera: ASI ZWO 178MM
• Mount: Sky Watcher AZ-EQ6 PRO
• Filters: Astronomik filters for channels L (IR/UV), R, G, and B; narrowband Astronomik filter 6 nm for channel Ha; filter size 36 mm in filter wheel QHYCFW3M-US
• Total integration time (12 h 33 min): 
  - L: 64 x 140 s
  - R: 32 x 140 s
  - G: 32 x 140 s
  - B: 34 x 140 s
  - Ha: 25 x 900 s
• Calibration shots: 60 x flats per channel, 60 x bias
• Used software: Stellarium, PHD2, Astro Photography Tool (APT), Astronomy tools, SharpCap, PixInsight Core 1.8.9-1 Ripley, plugins for PixInsight (StarXterminator, NoiseXterminator, BlurXterminator)
• Processing mode: L_RGB_Ha
• Sky quality: Bortle 4 (21.48 mag/arc sec2)
• Elevation above sea level: 850 m
• Date: March 2023
• Location: Vurmat / Radlje ob Dravi; Slovenia