Andromeda Galaxy

The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the constellation Andromeda. It is also known as Messier 31, M31, or NGC 224, and is often referred to as the Great Andromeda Nebula in older texts. Andromeda is the nearest spiral galaxy to the Milky Way, but not the closest galaxy overall. It gets its name from the area of the sky in which it appears, the Andromeda constellation, which was named after the mythological princess Andromeda. Andromeda is the largest galaxy of the Local Group, which consists of the Andromeda Galaxy, the Milky Way, the Triangulum Galaxy, and about 30 other smaller galaxies. Although the largest, Andromeda may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and may be the most massive in the grouping.

In image processing, computer graphics, and photography, high dynamic range imaging (HDRI or just HDR) is a set of techniques that allow a greater dynamic range between the lightest and darkest areas of an image than current standard digital imaging techniques or photographic methods. This wide dynamic range allows HDR images to more accurately represent the range of intensity levels found in real scenes, ranging from direct sunlight to faint starlight, and is often captured by way of a plurality of differently exposed pictures of the same subject matter.

For the 2010 version see here.

Image Data: Andromeda Galaxy

Lens / Scope: William Optics Megrez 102 S.V. with WO Type II 0.8x FF/FR 

Focal Length: 571.2mm 

F/stop: f/5.6 

Exposures: 

Ha: Stack of 30 1200-second exposures (10:00 hours total exposure)

RGB: Stack of 192 420-second exposures (22:20 hours total exposure)

HDR: Stack of 50 60-second exposures (50 minutes total exposure)

Mount: Sky-Watcher HEQ5 Pro SynScan GOTO (CdC and EQMOD Control) 

Guiding: Sky-Watcher 80 with QHY5 (PHD Control) 

Camera: Canon 500D (Digital Rebel T1i) Baader Mod (EOS Utility Control) 

Mode: RAW 

ISO: Ha – 800 ;  RGB – 400  

White Balance: Ha –  Daylight ; RGB – Custom

In-Camera Noise Reduction: Off 

Filters: Astronomik Ha 12nm ; Hutech IDAS LPS

Dates: From August 26 2011 to October 21 2011

Location: Beja, Portugal 

Calibration: Darks, Flats, Bias. 

Processing: Calibrated, aligned and stacked in DSS. Post-processing in Photoshop.