Sunday, November 30, 2014

Finishing the Astronomical League Bright Nebula list anytime soon? Not very likely.

The ALBN requires 100 objects to be imaged, and I'm in need of 26 more to finish. There are 62 listed objects that I can choose from according to the published list. Let's see how that shakes out.

First eliminate the bogus object on the list, IC 425, although I'm tempted to image its supposed location and count that as one. This leaves 61 Objects.

Next, eliminate all the objects that are too low to image from the locations I plan to use. The southernmost locations are the Iowa and Nebraska star parties at 41.8 and 42.6 degrees north, respectively. As a guess, these allow imaging to about 40 degrees south declination. This eliminates five objects: IC 4628, Gum 12, NGC 2736, NGC 6164, and NGC 6188. There are now 56 objects.

Now let's assume I want to avoid imaging objects that require very dark sites, namely those with Lynd's brightness 6. This includes eleven objects (Sh 2-218, LBN 619, 1064, 683, 8, 10, 1091, 19, 70, 140, and 434). There are now 45 objects available. (Tossing out the brightness 5 objects eliminates another 12 objects, leaving 33.)

Let's see how far I could get just doing the brightest objects. Brightness 1 has 4 objects, 2 has 4, 3 has 5, and 4 has 7. The total without dipping into the 5s is 20. There are some objects without assigned brightness that could add some to this: NGC 2174, Sh 2-264, LBN 962, NGC 2149, NGC 2296, NGC 6357, NGC 6729, and IC 4812. These lift the total to 28! Only two objects to spare!!

Actually, LBN 20 and 22 (brightness 5) share a field, so there are three to spare.

A first pass at the optimum months for imaging these can be found using SkyTools3.

January: IC 2169, LBN 943, Sh 2-280, NGC 2296, IC 468, NGC 2359
February:
March:
April:
May: LBN 1122
June: LBN 20, LBN 22, NGC 6357, Sh 2-12, Sh 2-13
July: IC 4812, NGC 6729, LBN 52, IC 4701
August:
September:
October:
November: IC 360, NGC 1555, NGC 1579
December: LBN 945, NGC 1931, Sh 2-264, NGC 1999, Sh 2-240, LBN 962, NGC 2149, NGC 2174, IC 2162

This is where the bad news rears its ugly head. Sixteen (nineteen minus the three spare) objects must be imaged during the winter months. Given the terribly cloudy (not to mention cold) winters we've had lately, this becomes problematic. It's probably going to be necessary to dip into the dimmer objects that are available in spring and summer. These include LBN 683, 1088, 10, 1091, 19, 11, 8, 70, and 490. That's only 9, though, which means that at least seven of those winter objects will need to be imaged.

Conclusion: I might be at this for a couple of years yet!

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