Object of the Week, December 8, 2013 – NGC 281 - IC1590 - HD 5005

NGC 281 - IC 1590 - HD 5005, A Winter Trapezium - Bok Globules

Emission Nebula - Open Cluster - Multiple Star - Bok Globules
Cassiopeia
R.A.: 00h52m49.2s
Dec.: +56°37'39" (2000)

MAG 7.4 (NGC 281) MAG 12.3 (IC 1590) MAG 7.8 (HD 5005)

NGC 281 is also known as the PAC Man Nebula, having roughly the same shape as the old video game character of the same name. It is an emission nebula, discovered in August 1883 by E. E. Barnard, is about 10,000 light years distant, 30 arc-minutes across and is very nice when viewed using a variety filters, my own favorite being the NPB filter. NGC 281 can be thoroughly enjoyed using even the smallest of telescopes, and in my 25" f/5 is terrific eye candy. This guy is not really much of a challenge, but so what? Here is a photo via APOD...

Attachment 986

IC 1590 is a small 12th magnitude open cluster near the center of NGC 281. It contains approximately 65 members and is only about 3.5 million years old, making this a very young cluster. I'm not usually much of an open cluster observer, but this report is mostly about multiple objects in the same field of view, so that makes me interested :D

HD 5005 = ADS719 = Burnham 1 - Speaking of multiples, there is a dandy multiple star at the heart of NGC 281/IC 1590, the trapezium HD 5005, with members as follows;

-------V mags--------sep(")-----pa
AB___8.6,10.1_____1.6_____79
AC_____9.2_______3.9_____134
AD_____9.8_______8.9_____193
AE_____12.5______16.6____336

Lastly, there are several Bok globules scattered throughout NGC 281, which are large molecular clouds of dust and gas that can condense to eventually form new stars. The easiest globule to see is located about 3 arc-seconds NE of HD 5005. I could not find any designations for these globules, but I'll assume that such designations exist somewhere. Read about Bok globules here...

http://heritage.stsci.edu/2006/13/caption.html

My own best observation of this area didn't really include NGC 281 itself, because the field of view of the 82" at McDonald Observatory in Ft. Davis, Texas is only 5 arc-minutes wide using its lowest power! Here is what I wrote about this object in 2006... "Although this bright nebula itself is way too big for the 5 arc-minute FOV, the targets here were really the Bok globule near the middle and the nearby HD 5005 trapezium-like multiple star. The Bok globule was clearly visible, but not nearly as contrasty as I thought it would be. The multiple star was obvious, and made for a very pretty picture. At 812X the 1.6" AB pair was easily split. Of course, there was a lot of nebulosity coursing through the whole area." I could have looked around this area for a long time, but there were 2 dozen people waiting in line behind me for their turn at the eyepiece :(

Attachment 985 This photo was 'borrowed' from my friend Dave Jurasevich's great web page... http://starimager.com/Home_Page.htm ... and only shows a portion of NGC 281, concentrating instead on the Bok globules and other fascinating structures in that area.

Give it a go and let us know!

Hi Paul,

Checking my notes show that I haven't looked at NGC 281 for quite awhile as my most recent observation is from 1997! Here's what i wrote then:

"Large-ish emission nebula is Cassiopeia that has a distinct dark lane, and parts of the bright nebula are very obvious. Detectable without a filter, best with UHC. Reminiscent of the North American Nebula but small and with more detail. 73x, 133x, 20" f5 Obsession"

Your description of the Bok globules and IC 1590 has me eager to have a long look with my 28" on the next clear dark night, thanks!

Here are my last notes from 2007 with my 18-inch f/4.3. Well worth another visit!

Remarkable view of this detailed emission nebula/cluster at 115x and 220x. Without a filter at 220x about three dozen stars are visible in the region of the nebula, including a number of faint stars. At the center of the cluster (IC 1590) and nebula (NGC 281) is the multiple star Burnham 1, a striking triple with a difficult 4th component at 1.1". A 13" pair of mag 11.5 stars lie 0.9' SW of Burnham 1.

The nebulosity responds dramatically to a UHC or OIII filter. The two brightest regions have a butterfly appearance with the two lobes or wings partially divided by a curving dust lane oriented roughly N-S. A fainter detached portion is on the southeast side. The overall dimensions extend to 15'-18'. The two lobes are fairly similar in size and surface brightness, though the following section is larger including the southern piece. The western section has the brightest and most sharply defined edge running along its southern side and oriented E-W. A long straight dust lane extends along the southern boundary of both lobes and defines the sharp edge on the western lobe. The curving central dust lane intrudes into the nebula on the south side and nearly divides the two sections, though weaker nebulosity connects the two wings.

Paul,

perhaps the object itself is not the challenge but the details inside are, so, good choice for the OOTW.

I was always to much concentrated to observe the challenges itself like the Bok globules that I ever looked at Burnham 1 in detail. Thanks for the reminder.

The darker Bok was visible with my 16" under very good transparency but exactly as you said only with a low contrast - no comparison with the pictures. The smaller Bok to the S was much harder to detect with my 27" but it works.

Another detail I love is the sawtooth structure at the inner corner of NGC 281.

My old sketch with the 20x125 Bino shows not much structure but the sketch of Rainer Mannoff with a 16" Dob shows very much the detail what I remember.

Hi,

Nearly 10 years later I have observed NGC 281 several times but because of its detailed structure it’s not an easy object. The nebula can be observed with UHC and OIII-filters but does not reveal the details that are known from some fotos. I decided that for me the UHC works better because it reveals more faint details than the OIII does. An interesting detail within the nebula is the round dark nebula inside that could be spot relatively easy.

Below you find a sketch with my 14 inch Dobson using an 25mm 100° eyepiece and UHC-Filter that gives me a field of 1,5°.

Attachment 4529

I observed NGC 281 with 25“ too. The details are very impressive but as I mentioned the object itself seems to have its difficulties.

Oliver