M100 and NGC4312

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2014/03/26 - I spent two night on M100 and NGC4312. The Moon rose late so I had a nice black sky. The second night there were some clouds, so I rejected some frames. FWHM was between 2.28" and 3.18".

Messier 100 (also known as NGC 4321) is an example of a grand design spiral galaxy located within the southern part of constellation Coma Berenices. It is one of the brightest and largest galaxies in the Virgo cluster, located approximately 55 million light-years distant from Earth and has a diameter of 107,000 light years. It was discovered by Pierre Méchain on March 15, 1781 and was subsequently entered in Messier’s catalogue of nebulae and star clusters after Charles Messier made observations of his own on April 13, 1781. The galaxy was one of the first spirals to be discovered, and was listed as 1 of 14 spiral nebulae by Lord William Parsons of Rosse in 1850. Two satellite galaxies named NGC 4323 -connected with M100 by a bridge of luminous matter- and NGC 4328 are present within this galaxy.

Messier 100 is considered a starburst galaxy with the strongest star formation activity concentrated in its center, within a ring - actually two tightly wound spiral arms attached to a small nuclear bar with a radius of 1 kilo-parsec - where star formation has been taking place since at least 500 million years ago in separate bursts. As usual on spiral galaxies of the Virgo Cluster, in the rest of the disk both star formation and neutral hydrogen, of which M100 is deficient compared to isolated spirals of similar Hubble type, are truncated within the galaxy's disk, which is caused by interactions with the intracluster medium of Virgo.

Object information
Name : M100 and NGC4312
Type : Galaxy
Constellation : Coma Berenices
Distance : 55M light-year
Apparent dimensions : 7.4' x 6.3'
Apparent magnitude : 10.10

Image information
Image date : 2014/03/26, 2014/03/25
Right ascension : 12:22:42.089
Declination : 15°42' 31.87"
Focal length : 1381.47 mm
Focal ratio : f/5.44
Image resolution : 0.806 arcsec/pixel
Field of view : 40' 47.0" x 33' 13.1"
Sensor temperature : -30°C
Light frames : 12 hours total exposure time
24x 900 sec. luminance unbinned
8x 900 sec. red unbinned
7x 900 sec. green unbinned
9x 900 sec. blue unbinned
Image acquisition with CCDAutoPilot and Maxim DL
Auto-guiding with Maxim DL
Auto-focusing with FocusMax
Bias frames : 100x unbinned
Dark frames : None
Flat frames : 24x luminance unbinned
24x RGB unbinned
Automated sky twilight flats with CCDAutoPilot
Processing : PixInsight for calibration, alignment and integration.
Adobe Photoshop CS6 for final touch.

Equipment information
Telescope : Robtics 10" 2000mm f/8 Ritchey Chretien
Corrector : Astro-Physics CCDT67 Focal Reducer
Focuser : Moonlite CS Ritchey Chretien focuser with high resolution stepper motor
Mount : ASA DDM60 Pro direct drive german equatorial mount controlled with AutoSlew
Camera : QSI 683wsg-8 cooled CCD camera with Kodak KAF-8300 sensor and Off Axis Guide (OAG) port
Guidecamera : Starlight Xpress Lodestar autoguider
Filters : Astrodon Tru-Balance E-Series LRGB & Astrodon 3nm H-α, 3nm O-III, 3nm S-II and 3nm N-II
Observatory site : Etten-Leur, The Netherlands