Galaxies
The Andromeda Galaxy
The Andromeda Galaxy (Messier 31), the largest galaxy in the Local Group, 2.5 million light-years away – photographed by Pete Lawrence.
Target details
The Andromeda Galaxy (Messier 31) is a spiral galaxy about 2.5 million light-years away. At around 220,000 light-years across it's the largest galaxy in the Local Group, which also includes the Milky Way, the Triangulum Galaxy and about 44 smaller galaxies. At magnitude 3.4 it's one of the brightest Messier objects, visible to the naked eye on moonless nights even from areas with moderate light pollution. Andromeda and the Milky Way are expected to collide in about 4.5 billion years, eventually merging into one giant galaxy.
Capture details
Data captured over numerous session in August & September 2017.
4 Pane Mosaic in 2x2 Layout
136x 10 minute exposures at ISO400 across the 4 panes.
Equipment details
Skywatcher Quattro 200 CF
NEQ6 Pro
Canon 40d (IR Filter removed)
Skywatcher ST-80
QHY5L-II
Processing details
This image was processed in Pixinsight & Lightroom.
Processing Individual Panes
Calibration and Stacking of each pane seperately.
Dynamic Crop - Each pane was cropped to remove any black edges.
Fast Rotation - To orient pane as it will be located in mosaic
Dynamic Background Extraction - Applied to each pane to remove background gradients.
Photometric Colour Calibration - To colour calibrate the image.
SCNR - To neutralise green.
Deconvolution - To bring out some fine detail. (Not very effective in this image due to lack of good data)
To Create Mosaic
Star Alignment - To create mosaic layout and registration data.
Gradient Merge Mosaic - To create mosiac image.
Processing Mosaic
Dynamic Crop - To remove black edges and gaps in the mosaic.
Multiscale Linear Transform - Noise reduction.
Histrogram Transformation - To stretch the image and bring out the data.
HDR Multiscale Transform - To recover additional data in core.
Curves Transformation - To increase contrast.
Local Histogram Equialisation - To sharpen & increase detail.
Histogram Transformation - To darken background, using RangeMask to protect galaxy centre.
Dark Structure Enhance - To increase contrast in arms / bands.
Curves Transformation - To improve contrast on entire image.
Curves Transformation - To darken background, using Rangemask to protect galaxy.
Export as JPEG and import into Lightroom.
Increase Contrast (+20)
Increase Saturation (+35)
Export final JPEG for upload.
Quick facts
- What is The Andromeda Galaxy?
- The Andromeda Galaxy (Messier 31) is a spiral galaxy about 2.5 million light-years away. At around 220,000 light-years across it's the largest galaxy in the Local Group, which also includes the Milky Way, the Triangulum Galaxy and about 44 smaller galaxies.
- Where is it in the sky?
- In the constellation Andromeda.
- What are its catalogue names?
- M31
- When was this photo taken?
- 1 September 2017
- What equipment was used?
- Skywatcher Quattro 200 CF, NEQ6 Pro, Canon 40d (IR Filter removed), Skywatcher ST-80, QHY5L-II
- Where was it taken from?
- Lisburn, Northern Ireland.