Archive for July 2021

NGC 6572, Planetary Nebula in Ophiuchus: July 2021 Observer’s Challenge Report #150

July 19, 2021

Roger Ivester, North Carolina


Sue French, New York

July 2021

Report #150

NGC 6572, Planetary Nebula in Ophiuchus

Sharing Observations and Bringing Amateur Astronomers Together

This month’s target

Our object for the 150th monthly edition of the Observer’s Challenge is the tiny, but bright, planetary nebula NGC 6572, variously nicknamed the Emerald Nebula, the Blue Racquetball, and the Turquoise Orb. These names highlight the range of hues perceived by different observers. The nebula is young, perhaps only a few thousand years old. Its diminutive size led to its inclusion in some early star catalogs. NGC 6572 has a visual magnitude of 7.3, as determined by Stephen O’Meara, while its central star dimly shines at 13th magnitude. As with many planetary nebulae, published distances vary wildly. Values in the vicinity of 5000 light-years seem most likely. This pretty little gem was discovered in1825 by Wilhelm Struve.

NGC 6572 displays bipolar outflows in deep images. There’s evidence of interaction between the collimated outflows and the nebula’s elliptical shell. The interaction has broken up the elliptical shell such that parts of the shell have been accelerated, while the outflow has been slowed down and/or deflected. This supports the idea that such outflows are common in planetary nebulae and may play an important role in shaping nebular shells.…520..714M/abstract 

Mario Motta: Observer from Massachusetts

NGC6572 is a very tiny object (16×12 arc seconds). Got this last week, poor night with some turbulence, with an H alpha, O3 , and S2 filters. Very short exposures as it is very bright. Visually a small “blue spot”.

Image attached, about 20 minutes each filter, O3 dominated…thus very blue. No detail that I can see. Only good image on line I found is by the Hubble, but can’t match that one! However, a nice object.

Complete Observer’s Challenge Report: Click on the following link…


Roger Ivester: Observer from North Carolina

NGC 6572 – Planetary Nebula in Ophiuchus 

Date:  May 2021 

Telescope:  6-inch f/6 Newtonian Reflector 

Eyepiece:  20mm + 2.8x BarlowSketch Magnification:  128x

NELM:  ~4.9 Magnitude

I knew that fine detail of this planetary would not be possible from my back yard, using a 10-inch reflector.  So, I chose to use a 6-inch f/6 reflector, mostly for convenience, but not really expecting much difference from the 10-inch.

With the 6-inch, this planetary is very small, mostly round and featureless, but with a pale bluish color.  

This is definitely a large telescope object for the visual observer.  

Peter Vercauteren: Observer from Italy

Telescope: 18-inch f/5 Otte BinoDobsonian

Magnification: 4.5mm @ 507x