10 replies to this topic

[PhilH]

Deep-sky objects can be challenging for several reasons. Some are especially faint, while others are especially small, and still others are so large that they can't fit into a single eyepiece field. Or the problem might be that a particular target is so close to another, noticeably brighter object that the light from that intruder all but obliterates the quarry. The latter problem plagues planetary nebula Abell 12. It shines at about 14th magnitude, which is not exactly bright, but is also not exceptionally dim for a telescope 10 inches (25 cm) or more in aperture. The problem, however, is that it is located a scant arcminute away from 4th-magnitude Mu (μ) Orionis. That's why it's known by the nickname the Hidden Planetary.

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[David Knisely]

The OIII filter in my 10 inch Newtonian under dark skies makes Abell 12 almost trivial to see, as it really knocks down the light from Mu Orionis while preserving the oxygen III emission of the nebula. 

[John O'Hara]

What impresses me is that Phil observed these challenge objects from his suburban back yard with a NLM of no better than 5.  

[TelescopeBah]

I enjoyed the challenge with my 12 inch LB, it seemed to me that a O-lll was a must to glimpse it, but I did see it! Thanks Phil!

[Alex Swartzinski]

I just got in from observing this object under mid NELM 5 skies with a 15" dob.

 

With a UHC and 330x, the nebula was detectable as a round dim glow which is slightly brighter in the center. It was completely detached from the star halo at this power and fov. Using lower powers, Mu Orionis hides the planetary. I also attempted to observe this object unfiltered but I wasn't able to make any detections without the UHC.

 

I've been meaning to give Abell 12 an attempt for a long time and this challenge served as a great reminder every time I opened Cloudy Nights!  Thanks for the great challenges Phil. 

[monolithic]

I was able to detect this planetary with my 10" under Bortle 6 skies, using my DGM NPB filter and high power. Here are my notes:

"This dim planetary appears very close to Mu Orionis, presenting as a round, featureless extension of the star's glare, situated at the 10-11:00 position at the time of writing. It is an averted vision-only object and would be invisible without the filter. I was able to spot it with the 12mm (148x), but my best view was with the 6.5mm (274x) and filter."

I honestly wasn't sure if I could see it with this level of light pollution, but I gave it a shot and was pleasantly surprised.

[Sky King]

Another cosmic treasure! Thanks Phil!

 

I took a few images with a C8/Hyperstar, ASI678MC, NBZ II filter. It wasn't really visible in my Bortle 8 view without the filter.

 

[Sky King]

2-14-24

 

I tried something different last night and got additional detail: ASI533MC Pro, C11, Meade .33 reducer, UV/IR filter. 99 images, 30-seconds each for 50 minutes total. 

 

Some of Phil's targets are so special you can visit them again and again.

 

 

[TelescopeBah]

Nice thanks for sharing!

[Alvin Huey]

Thanks for sharing Phil. 

 

This is one of my favorite Abell PNes.  It was pretty easily seen with my 22".  One of the key things is to make sure that the optics are clean as any glare could wash out the Abell.  And don't be afraid to use magnification to create seperation.  It is only 1' from a 4th mag star!  So bump up the magnification to 300+.

Edited by Alvin Huey, 23 February 2024 - 06:33 PM.

[micromaxcomputer]

"Hidden" Planetary Nebula Abell 12 in Orion. Meade LX200 12" 0.63FR with Astronomik CCD CLS filter on ZWO ASI174mc cooled camera, 50 45sec images put thru DSS / PS