|Globular Cluster M3 - DSLR
The globular cluster M3 lies in the constellation Canes Venatici, on the border with Bootes. Although it may contain as many stars at the Great Hercules Cluster M13, it
is a third farther away at a distance of about 33,000 light years, and therefore somewhat dimmer and visually smaller. Furthermore, the cluster contains a dense core, with
half of its 500,000 stars contained within an 11 light-year radius of its core. For comparison, only a dozen stars reside within 11 light-years of our sun. M3 is also notable
for the unusually high number of variable stars, which have been used to calculate the distance to the cluster. Visually through a telescope, the dense central concentration
stars of M3 obscures resolution of the core. M3, truly, hides its heart from us.
The image above is a cropped "snapshot" with a Canon 60Da, averaging just four 1-minute exposures at ISO 1600, through an Astro-Physics Ricardi-Honders 12" f3.8
telescope. To keep the test simple, the image was obtained without guiding, used the camera's internal dark subtraction, and no flat field. I did not do any fancy
processing, just curves and levels in Photoshop Raw mode, before stacking the 4 images.
A comparison CCD image through a telescope with a similar aperture is shown below, obtained with an ST10XME camera, with an AP 0.67x reducer, through a 12"
Meade LX200R telescope. I combined exposures of 25 minutes of red, and 20 minutes each of blue and green. Extensive processing was applied with Maxim DL,
CCDstack, and Photoshop.
Music: You've got to hide your love away, by the Beatles