M 99
About image
Messier 99 is a spiral galaxy in Coma Berenicis constellation: it belongs to the Virgo Cluster of which is one of the brightest component.
Its distance from our galaxy is around 60 million light years, with an extension of 79000 light years.
It is characterized by two bright spiral arms with asimmetric shape, maybe due to interaction with another galaxy, with many HII regions well visible (no Ha data were used for this image).
From Wikipedia I discovered that M 99 was the second galaxy, after M 51, for which Lord Rosse in 1848 was able to see clearly the spiral structure.
For this image I had to struggle with an annoying light infiltration from the top left side till near the area of the galaxy, not clear the reason (in my observatory all the leds are obscured).
Fortunately I was able to recover the issue with a "focused" application of Graxpert.
Technical data
Optic GSO RC12 Truss - Aperture 304mm, focal lenght 2432mm, f/8
Mount 10Micron GM2000 HPSII
Camera ZWO ASI 2600 MM Pro with filter wheel 7 positions
Filters Astrodon Gen2 E-Serie Tru-Balance 50mm unmounted LRGB, Ha 5nm
Guiding system ZWO OAG-L with guide camera ASI 174MM
Exposure details L 54x300" bin3 -15C gain 100
R 19x300" bin3 -15C gain 100
G 18x300" bin3 -15C gain 100
B 21x300" bin3 -15C gain 100
Total integration 9h20'
Acquisition Voyager, PHD2
Processing Pixinsight 1.8, DxO Photolab 9, BlurXTerminator, NoiseXTerminator, StarXTerminator
SQM-L 21.49
Location Promiod (Aosta Valley, Italy), own remote observatory
Date 8/19 April 2026
© Roberto Marinoni 2019 - All rights reserved