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PostPosted: February 12th, 2012, 11:31 pm 

Joined: October 12th, 2009, 3:28 pm
Posts: 4249
Location: Baton Rouge, LA
Today's APOD is a composite pieced together over a number of nights by Rogelio Bernal Andreo. It's a 75-light-year span of sky that includes the three Orion belt stars, the Flame Nebula, the Horsehead Nebula, the Running Man and M42.

The image:

Last edited by Christopher K. on August 3rd, 2014, 8:59 pm, edited 2 times in total.

PostPosted: March 20th, 2012, 10:16 am 

Joined: November 15th, 2010, 12:45 am
Posts: 36
Location: Baton Rouge, LA
Wow.... that's a magnificent image. Thanks for sharing, Chris!

 Post subject: Horsehead Nebula
PostPosted: January 20th, 2014, 2:40 pm 

Joined: October 12th, 2009, 3:28 pm
Posts: 4249
Location: Baton Rouge, LA
A closeup of the Horsehead (also known as Barnard 33) is the December image in the 2014 Astronomy calendar from Brown Trout Publishers.

In Ben's "What Have You Learned Lately?" thread (in General Discussion), Trevor mentions wanting to get the Horsehead manually. It lies a half-degree south of Alnitak and a half-degree east-northeast of slightly dimmer Sigma Orionis.

PostPosted: August 3rd, 2014, 9:39 pm 

Joined: October 12th, 2009, 3:28 pm
Posts: 4249
Location: Baton Rouge, LA
"Undoubtedly the best known example of a dark nebula in the entire heavens" is how Burnham describes it. The Horsehead was detected in photographs in the 1880s by Pickering and shows clearly on a 1900 plate. Its size is approximately 6' x 4' and it is about 1600 light-years away. We are able to detect the Horsehead shape due to its jutting in front of the bright nebula IC 434, which is no doubt mostly illuminated by Alnitak.

Burnham considers it "one of the most difficult objects" for the casual viewer, and states an eight- or ten-inch telescope with a a wide-angle eyepiece (and a "really excellent sky") begins to reveal a hint of its shape. Obviously, dark nebula are usually not assigned a magnitude as that number is a measurement of brightness, yet The Starry Night Pro Plus give it an 11.0; I suppose the editors are implying the difficulty is equivalent to a mag-11 bright object.

Last Monday's APOD is an image of this nebula revealing detail I've never seen; it combines infrared information from Hubble with blue, green, red and h-alpha from Argentina.

Below are the times during which the Horsehead reaches its culmination of fifty-seven degrees in the Baton Rouge sky...
9 October = 5:34am
13 October = 5:18am
17 October = 5:03am
21 October = 4:47am
25 October = 4:31am
29 October = 4:16am
Times above are Daylight. Times below are Standard.
2 November = 3:00am
6 November = 2:44am
10 November = 2:28am
14 November = 2:13am
18 November = 1:57am
22 November = 1:41am
26 November = 1:25am
30 November = 1:10am
4 December = 12:54am
8 December = 12:38am
12 December = 12:23am
16 December = 12:07am
20 December = 11:47pm
24 December = 11:31pm
28 December = 11:16pm
1 January = 11:00pm
5 January = 10:44pm
9 January = 10:29pm
13 January = 10:13pm
17 January = 9:57pm
21 January = 9:41pm
25 January = 9:26pm
29 January = 9:10pm
2 February = 8:54pm
6 February = 8:38pm
10 February = 8:23pm
14 February = 8:07pm
18 February = 7:51pm
22 February = 7:36pm

More information:
Burnham's Celestial Handbook, pp. 1339-1344.

28 July 2014 APOD:

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