NGC 6210 -- Planetary Nebula in Hercules
Turtle Nebula
When the images of NGC 6210 from the Hubble Space Telescope were made available to
the public, the consensus was that it looked like “turtle swallowing a seashell”.  NGC 6210
has been referred to as the Turtle Nebula ever since.

I could not recognize any turtle eating dinner in my small 110mm refractor.  At low power the
Planetary Nebula is star-like.  At a magnification of 96x it is no longer star-like but a tiny
bluish glow with an extended (not star-like) bright center. By pushing the power up to 257x
and waiting for the atmosphere to settle down, I could see the bright center dissolve into
knots.  These pseudo-knots were very fleeting, and I was never sure of their exact location.
The impression I got were that they were absent from the true center of the nebula.  Try as I
might, I could not make out the 13th magnitude central star.

The Oxygen III nebula filter is not needed (this is a bright nebula) and did little to enhance the
view.  The filter was however initially helpful separating the star-like planetary from the
surrounding stars while at low power.