Object of the Week - Nov 26th, 2017 - NGC 2818 - Both of Them!

[Paul Alsing]

Object of the Week - Nov 26th, 2017 - NGC 2818 = Hen 2-23 = WRAY 16-38 = ESO 372-13 = ARO 508, in Pyxis

R.A.: 09h16m01.7s Dec.: -36°37'39"
Size: 36"
Magnitude: 11.90

I sure like “2-fers” in the eyepiece, and this is a nice one. NGC 2818 is a planetary nebula apparently within the open cluster NGC 2818... yes, they both have the same designation, although the cluster of often referred to as NGC 2818A. Up until the end of the last century it was thought that the nebula was actually within the cluster, but in 2001 a comprehensive radial velocity study of stars in the cluster (by Mermilliod et al.) demonstrated that they are just a superimposed pair of objects in a chance alignment.

http://cdn.iopscience.com/images/153...Full/tb1_1.jpg

… from this paper…

http://iopscience.iop.org/article/10.1086/524414

… although none of the planetaries have yet to be proven to be members of their respective clusters. I’m going to be sure to make this list a new observing project for myself, it should be fun!

Getting back to NGC 2818, from my usual observing location in the desert 60 miles east of San Diego, CA., these objects culminate at only about 22° above our southern horizon, in early March, so my views have not been particularly impressive, but nevertheless they have been quite appealing. The cluster itself has quite a few stars but they are all fairly faint, and the planetary is perhaps slightly west of the cluster’s center, is oval-shaped, and there are hints of some structure in moments of good seeing. The Hubble picture will make you want to head to somewhere south of the equator to get what must be really amazing views…

https://apod.nasa.gov/apod/ap140713.html

As always, give it a go and let us know

[Ivan Maly]

Although technically rising here, it's an ungrateful target from my home latitude. Observing from Central Australia in (our northern) springtime with my travel 6" f/12 Mak with a 6.5-19.5 mm Pentax zoom and a fine 9x50 finder, I recorded:

"Pyxis. NGC 2818. PN. According to Uranometria, there is both an OC and a PN, and the NGC number refers to both. Although the PN [is] in a group of stars, it [the group] is poorly detached and not dissimilar to what’s common in the field. The PN is sizable and has a relatively low SB. Slight annularity may be suspected."

[Bertrand Laville]

Hi All,

Here is a drawing for an observation made at Tivoli Lodge, Namibia, with a 20" Obsession, in of course a very good sky: SQM 21.60, nelm 6.85, and the target was at 71° above horizon.

2819

Details upon at: http://www.deepsky-drawings.com/ngc-2818/dsdlang/en

Clear skies
Bertrand
http://www.deepsky-drawings.com/

[Uwe Glahn]

Nice pair Paul. I have two observations from Namibia, because from Middle Europe the pair is also to low in the sky.

12", 214x, NELM 7m0+
wonderful PN and surrounding star field, located within the eponymous OC; Pn elongated 2:3 E-W; N and S edge better defined; necking between both edges visible, very nice view

17", 455x, NELM 7m0+
3:2 elongated NE-SW; long sides better defined; conical shape between edges; stellar spots around the middle part; no CS visible
2820

[wvreeven]

I unknowingly observed this pair from the Rio Hurtado valley in Chile tonight with my 20" telescope in an attempt to see all NGC and IC objects in Pyxis and then some. The cluster is very pretty. At 83x it is a very nice concentration in the Milky Way. At 320x it just about fits in the FOV of the 8 mm Ethos eye piece, making it some 19' wide. The planetary nebula already is visible as a roundish glow at 83x. At 320x it takes a hamburger shape. At 545x I can see the fainter outer parts on one side. Unfortunately no further details were visible in the center part.