Jewel Box (NGC 4755)

clic for 50% size 1389 x 1025 (703 kB)

About this Image

The great variety of star colors in this open cluster NGC 4755, situated less than 1 degree to the south-east of the brigth star beta crucis underlies its name: The Jewel Box. One of the bright central stars is a red supergiant, in contrast to the many blue stars that surround it. The cluster, also known as Kappa Crucis contains just over 100 stars, and is about 10 million years old. The Jewel Box lies about 7500 light-years away, spannning 20 light-years across. North is right.

The first time I used strings in front of the refractor lens to generate the spikes.

Below you find a crop on the center in 120% size.

Technical Details


105mm TMB refractor with flattener at f/6.5

Mount AP-400 GEM
Camera SBIG STL-11000M at -20C, internal filter wheel
Filters Astronomik LRGB
Date Aug 13, 2004.
Location Hakos/Namibia
Sky Conditions mag 6.5, high transparency, temperature 10 C,
Exposure LRGB= 10:10:10:10 min (5-minute sub-exposures)
all 1x1.
Processing Image aquisition in Maxim DL 4.0; Image calibration, aligning, mean stacking, DDP and color synthesis in ImagesPlus;
Photoshop: color balance, cropped, unsharp mask;