Object Of The Week April 10, 2022 - NGC 3699 and friends

[wvreeven]

NGC 3699, Ced 114, Hen 2-65, Wray 16-90, PK 292+01.1, PNG 292.6+01.2

Planetary Nebula

Centaurus

RA: 11 27 57.70
DEC: -59 57 28.0

Mag: 13.00

Diam: 0.747'

This week I take you down to the southern Milky Way in Centaurus, right between Carina and Crux. NGC 3699 was discovered by John Herschel on April 1st, 1834. Its distance is estimated to be 1620 parsec or 5284 light year. It is a fascinating object to look at since the planetary nebula is divided in two by a dark lane.

ngc3699_eso.jpg

The dark lane isn't very prominent in this image (https://www.eso.org/public/images/potw1550a/), taken with the ESO Faint Object Spectrograph and Camera (http://www.eso.org/public/teles-inst...la/ntt/efosc2/) at La Silla. But it is very clearly visible visually, even with my 12" dob in my light polluted backyard in La Serena. With my 20" dob without a filter from a very dark location it looked a lot like Pacman with it's mouth open and occasionally the bar is extended all the way across the nebula. With an OIII filter, the effect is reversed. The fainter outer loop wasn't visible at all.

Lying very close to the galactic plane, there are no less than six other planetary nebulae within a 1º by 1º area!

Two of these, He 2-67 (mag 13.8, 5.0") and He-70 (mag 13.8, 35") I looked up with my 12" dob from my backyard in La Serena. He 2-67 was stellar and easily visible without a filter. Blinking with an OIII filter confirmed the identification of the nebula. He 2-70 possibly was visible as a large glow but the observation was unsure. Using my 20" dob from the very dark location I could fairly easily pick up the glow with an OIII filter. Without the filter the glow was suspected once I knew where to look.

The third planetary nebula that I observed from that same dark location with my 20" dob was Wray 16-93 (mag 16.1, 12"). Without a filter I saw was possibly was the central star at the location of the nebula. With an OIII filter a small oval glow appeared.

I intended to observe the fourth planetary nebula, PNG 292.9+01.0 (mag unknown, 20") as well but unfortunately SkySafari doesn't know about it so it slipped my attention. When I started writing this article I noticed the fifth and even sixth planetary nebulae, PNG 292.8+00.6 (mag unknown, 1.6') and PNG 292.4+00.8 (mag unknown, 38"), and obviously I didn't try to observe them yet. I'll have to revisit the region to try and observe these last three planetary nebulae.

Here is a finder chart for all 7 planetary nebulae, created with SkyTools Pro 4:

NGC_3699-Finder-Chart.jpg


As always,

"Give it a go and let us know!
Good luck and great viewing!"

[Raul Leon]

Too far South for me, but this looks to be a very interesting object!!

[Steve Gottlieb]

This fantastic planetary would certainly be one of the top favorites if it was located further north -- especially with the dark lane! Here's my last observation with a 24-inch from Australia --

This showpiece planetary appeared very bright, fairly large, ~70" in diameter. It displayed an excellent contrast response using an UHC filter at 200x. The planetary is bisected by a prominent, broad dark rift that slashes through the planetary from WSW to ENE (like Centaurus A!). The northern lobe is the more prominent: both larger and brighter. The shape of this lobe is semicircular with a round, outer periphery but with a fairly straight edge SW-NE in the interior due to the dark rift. The center of the dust lane is south of the geometric center of the planetary, giving an asymmetric distribution to the lobes. The rift itself is widest at the ENE end and tapers down towards the WSW end. Superb view at 350x as the extra magnification increases the contrast and confirms that the south lobe is fully detached by the dust lane at the WSW end. The compact planetary He 2-67 lies in the same field 11' SE.

[Uwe Glahn]

Happy birthday Wouter,

found two entries of your presented objects.

First of course NGC 3699 from Namibia with modest sized telescope.

sketch: 14.5", 283x, no filter, Seein III, NELM 7m0+ (Hakos/Namibia)
NGC3699.jpg
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After I visited He 2-70 the first time in 2015, I revisited it with larger aperture 2018 under a more than fine skies.

sketch: 28", 624x, [OIII], Seeing II, NELM 7m5+ (Gamsberg/Namibia)
Hen2-70.jpg
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[wvreeven]

Fantastic observation report, as always, Steve!

And great sketches, also as always, Uwe! Very interesting observation of He 2-70. I probably will revisit this one to see if I can up the magnification with the 20" and see if I can see more than a roundish glow.