Sky & Deep Sky

sword orion

Orion's Sword
The Great Nebula


The naked eye will look for three stars forming Orion's sword. Binoculars or a modest telescope will show that these three “stars” are loose groups of several individuals some of which can be seen in these pictures.
Angular separation 42 Ori - Nair Al Saif = 1°

1st group

1st group NGC 1977 in Orion is located near 42 Ori. It is an amazing complex of blue reflection nebula mixed with dark lanes and red emission nebula. The blue color comes from reflected starlight scattered by dust.
-42 Ori1323201892370184.59540B1V25.600
-45 Ori1323361901370775.26281F0IV7.400

2nd group

2nd groupTrapezium
mini trapeziumThe Trapezium is probably the best know multiple star in the sky. It is also one of the most interesting for the small telescope. In many double star catalogs it has become customary to designate the fours stars A, B,C, and D in order of right ascension (right to left in the pict.) rather than in the usual order of brightness. The fainest star, B, is an eclipsing binary with a period of 6.5 days. In 1975, star A was also identified as an eclipsing binary with a period of 65.5 days. In the picture are also visible the 11th magnitude stars E (beside A) and F (close to C). They are a well known observational challenge to amateur astronomers who often use them to judge the quality of the seeing as well as the quality of their telescopes.

NameFlamsteedStarSAOYaleHDMagn. TrapeziumDist.TypeTemp.°K.
(Theta 1)
41 OriC1323141895370225.133.71.470O637.600
Theta 243 Ori-1323211897370415.08-2.720O9V30.400

3rd group

3rd group3rd group
Nair Al Saif
(Iota Ori)
44 Ori1323231899370432.771.810O9III30.400

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Constellation pictures are modified screen displaies of Voyager II™ version 2.0 for the Macintosh™, the Astronomy Program of Carina Software, 12919 Alcosta Blvd Suite #7, San Ramon, CA 94583

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