Maynard's search for Abell Planetary Nebulae

MaynardP.040507

George O. Abell investigated the POSS First edition plates for the purpose of identifying galaxy clusters. He saw many previously unidentified Planetary Nebulae and created a list of 86, published in a paper titlled "Properties of Some Old Planetary Nebulae." The work was published in 1966. Four were later determined to be mis-identified (11, 32, 76 and 17).

I've seen a few of the Abell PNs through Slooh. I think I'll see how many I can image.

24-Oct 21:35
Abell 74
Other identifier: PK 72-17.1
21h 16m 52.0s +24° 08' 52"

24-Oct 21:40
Abell 68
Other identifier
PN G060.0-04.3
20h 00m 10.1s +21° 42' 55"

24-Oct 21:45
Abell 57
Other identifier: PK 58+6.1
19h 17m 04.9s +25° 37' 33"

24-Oct 21:50
Abell 54
Other identifier: PK 55+6.1
Other identifier: PN G055.3+06.6
19h 08m 39.1s +22° 58' 58"

24-Oct 22:05
Abell 66
Other identifier: PK 19-23.1
19h 57m 31.0s -21° 37' 44"

24-Oct 22:35
Abell 65
Other identifier: PK 17-21.1
19h 46m 34.0s -23° 08' 12"
_________________
Maynard Pittendreigh
www.pittendreigh.net

MaynardP.040507

24-Oct 23:05
Abell 5
02h 52m 15.0s +50° 35' 54"

24-Oct 23:10
Abell 4, possibly with some small galaxies
02h 45m 23.0s +42° 33' 04"

24-Oct 23:15
Abell 72
20h 50m 02.0s +13° 33' 29"
_________________
Maynard Pittendreigh
www.pittendreigh.net

JoshuaH.050701

I'm looking forward to seeing these, make sure to post your results.
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MaynardP.040507

MaynardP.040507

27-Oct 02:00
Abell 1
00h 12m 55.0s +69° 10' 00"

27-Oct 02:05
Abell 2
00h 45m 34.0s +57° 57' 35"

27-Oct 02:10
Abell 7
05h 03m 07.0s -15° 36' 23"

27-Oct 02:15
Abell 8
05h 06m 38.0s +39° 08' 08"

27-Oct 02:20
Abell 9
05h 29m 00.0s +36° 02' 00"

27-Oct 02:25
Abell 10
05h 31m 45.0s +06° 56' 02"
_________________
Maynard Pittendreigh
www.pittendreigh.net

DonaldB.080323

Maynerd,
I've tried (mainly using contrast stretching with various brightness curves) to bring out the Abells in your images, but you're right - they're very faint. The only one I'm fairly sure I was able to resolve was A57 (but even that is iffy). Although I can bring out individual stars in many of the others, A57 was the only one in which I was able to get even a glimmer of a ring.

The problem is that, as I'm sure you've seen, although the overall brightness of the nebula is reasonably high (e.g., magnitude 14.6 in the case of A72), the nebula is so diffuse (e.g., over a diameter of 2.1 arc-min in the case of A72). That diffuseness gives a mean surface brightness (e.g., 24.9 magnitudes per square arc-sec) that's way too faint to discern the entire nebula.

In my simple-minded way of calculating it, an object (like a star)subtending 2 pixels by 2 pixels in Dome 1's High Mag FOV covers about 2 to 2.5 square arc-seconds. That means that, at a mean surface brightness of 24.9 magnitudes per square arc-sec, the brightness of A72 over the 2x2 pixel area would be about magnitude 23.9 - too faint, even in Teide's very dark skies, to be seen I would think. I may be calculating this incorrectly, but I think that's why we can't see the Abells. (From these snaps, the limiting mean surface brightness looks to me to be about 22-23 mag/as2.)
Don

MaynardP.040507

30-Oct 20:00
Abell 1
00h 12m 55.0s +69° 10' 00"

30-Oct 20:05
Abell 2
00h 45m 33.8s +57° 57' 35"

30-Oct 20:10
Abell 3
02h 12m 06.0s +64° 09' 01"

30-Oct 20:40
Abell 6
02h 58m 41.0s +64° 30' 06"

30-Oct 20:45
Abell 84
23h 47m 02.0s +51° 23' 57"

30-Oct 20:50
Abell 86
00h 01m 31.0s +70° 42' 30"
_________________
Maynard Pittendreigh
www.pittendreigh.net

TomM.040629 · Member Joined: 19 Mar 2006 Posts: 396 Location: Storrs, CT

Well Maynard I have to say that the subject of Abell objects made me look up a few things . In sources of my books and of course the internet. I've known of the name for many years but from my own ignorance didn't pay it to much attention. That reason is because many of Abells objects contain NGC , PGC and MCG objects "within them". The Abell catalog came from studying plates of the POSS (Palamor Observatory Sky Survey) . His catalog contains about 4000 clusters each of which has at least 30 members - from PN's to Galaxies. Here is an example. Abell 400 has a member which happens to be NGC1128 - it appears as a double star at best to most of us. However that is not the case. It was imaged by CHANDRA to be a dumbbell looking item that in fact are 2 Black Holes orbiting each other. We here at Slooh have no where near instrument he had to use. But we have our fun too. Nice work Maynard!

MaynardP.040507

The best book I can find on the Abell PNs is the ABELL PLANETARY OBSERVER'S GUIDE by Alvin H. Huey http://www.faintfuzzies.com

It is a great book and the binding is perfect for taking outside and using at the telescope. I bought mine online.
_________________
Maynard Pittendreigh
www.pittendreigh.net