Object Of The Week April 10, 2022 - NGC 3699 and friends
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.
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:
Reply With Quote