M 51
About image
Messier 51, also known as the "Whirlpool Galaxy," is undoubtedly one of the most photographed celestial objects of all time.
It is located in the northern constellation of Canes Venatici (The Hunting Dogs) and is actually composed of two distinct, interacting galaxies: the larger galaxy on the left, with its blue spiral arms brimming with young stars, is classified as NGC 5194, while the bright yellow galaxy on the right is classified as NGC 5195. The interaction between the two galaxies began 240 million years ago: according to astronomers' simulations, in 70 million years the smaller galaxy will have completely merged with the larger one.
The red/pinkish areas on the spiral arms are HII regions, i.e. clouds of ionized hydrogen where new stars are born: I used a special filter to highlight them better.
Technical data
Optic GSO RC12 Truss - Aperture 304mm, focal lenght 2432mm, f/8
Mount 10Micron GM2000 HPSII
Camera ZWO ASI 2600MM Pro with filter wheel 7 positions
Filters Astrodon Gen2 E-Serie Tru-Balance 50mm unmounted LRGB, Astrodon Ha 5nm
Guiding system ZWO OAG-L with guide camera ASI 174MM
Exposure details L 69x300" bin3 -15C gain 100
R 22x300" bin3 -15C gain 100
G 22X300" bin3 -15C gain 100
B 22x300" bin3 -15C gain 100
Ha 45x300" bin3 -15C gain 100
Total integration 15h
Acquisition Voyager, PHD2
Processing Pixinsight 1.8, Photoshop CS5, BlurXTerminator, StarXTerminator, NoiseXTerminator
SQM-L 21.17
Location Promiod (Aosta Valley, Italy), own remote observatory
Date 12/13/14/29 December 2025, 24 February, 19 March, 7 April 2026
© Roberto Marinoni 2019 - All rights reserved