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Cone Nebula is a difficult dark nebula
in front of Sh2-273 diffuse nebula, so big that is bigger than the photographic
field. Above Cone there is the "Christmas Tree", an open cluster with the
stars outlining the figure of a tree, but upside-down. The nebula and cluster
are better visible in the enlargement below.
In this image there are at least other
two interesting objects: the famous Hubble variable nebula, resembling
a comet, near the lower border of the image, and the open cluster Trumpler
5, at 1° W of Cone, whose stars are very red. The cause of the color
is the absorption of blue light by the nebulas that are 3 times closer.
See also:
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| Optics | Pentax 75 apocromatic refractor, 75mm diameter |
| Focal Lenght | 500 mm |
| Focal Ratio | f/6,7 |
| Exposure Time | 45 min exposure |
| Film | Kodak E200 |
| Developement sensibility | 320 ISO |
| Location | Pian dell'Armà (PV, Italian Appennines), at 1400m |
| Date and time of exposure start | 12 january 2002, 23.58 UT |
| Mount | Meade 8" |
| Tracking | ST4 |
| Temperature and humidity | T=-4°C, RH=40% |
| Notes | - |
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