Not the usual type of shot for me - but with too much cloud of late (reducing imaging time) and general light pollution in my location (not good for LRGB) - I am happy enough with what I pulled out of this in the course of one night. (Updated 8th May with 2 hours L & 40 min RGB)
Messier 3 (also known as M3 or NGC 5272) is a globular cluster of stars in the northern constellation of Canes Venatici. It was discovered by Charles Messier on May 3, 1764 and resolved into stars by William Herschel around 1784. Since then, it has become one of the best-studied globular clusters.
This cluster is one of the largest and brightest, and is made up of around 500,000 stars. It is estimated to be 8 billion years old. It is located at a distance of about 33,900 light-years away from Earth.
Imaging telescopes or lenses: Takahashi FSQ106ED
Imaging cameras: QSI 6120i
Mounts: Takahashi EM 400 Temma 2
Guiding telescopes or lenses: Takahashi FS 60 CB
Guiding cameras: QHY CCD QHY 5 II
Focal reducers: None
Software: PHD 2, Pleiades Astrophoto PixInsight , Sequence Generator Pro SGP
Filters: Astronomik LRGB
Accessories: Robofocus Focuser, ATIK EFW2
Resolution: 2170 x 1533
Dates: 7th Apr & 2nd May '16
Astronomik Lum: 6x600" bin 1x1 + 6x300" + 7x240"
Astronomik Red: 6x240" + 10x300" bin 1x1
Astronomik Green: 1x240" + 10x300" bin 1x1
Astronomik Blue: 1x240" + 2x300" bin 1x1
Integration: 4 hours 50 minutes
Center (RA, Dec):(205.526, 28.378)
Center (RA, hms):13h 42m 06.198s
Center (Dec, dms):+28° 22' 40.877"
Size:43.6 x 30.8 arcmin
Pixel scale:1.21 arcsec/pixel
Orientation:Up is 90 degrees E of N
As taken: This is the area of the full image: