New moon, but clouds about. What can you do in a single very dark but rather dubious night? A globular cluster!
NGC 6752 is according to
APOD blessed with an unusually high number of Blue Stragglers - hot young blue stars formed from the merger of much cooler and more geriatric binary stars.
Our mission here was to try to strike a balance between showing the intensely saturated blue colour in the Blue Stragglers, and showing that they are very bright. This is very tricky with only 8 bits of JPEG to play with.
We've just recently started processing images in HSV space rather than RGB space. We are learning many things.
Out of the camera, the Blue Stragglers are
seriously blue, but preserving their saturated blue colour makes them look implausibly dim compared with their more red neighbours, and even dimmer compared with the abundant hyper-luminous red giants in the image.
We looked at a very fine APOD, where perhaps they've gone too far in the other direction, of showing the core of the globular as a creamy white.
Here, we've actually
desaturated the core a little bit, to find a middle ground.
A hunt around the
original image reveals something of the order of 15 very faint and very distant background galaxies. At least half a dozen should be apparent here.
FLI PL16803 on 20 inch PlaneWave. 81 x 5 minute subs. Field approx 40 min arc, north up. No moon, but about 20% of frames lost to cloud. Seeing was ok rather than brilliant, at about 2.2 sec arc. All robotics hardware, firmware, and software, and processing software as usual in done in house by us.
Very best,
Mike and Trish