Howard B
March 25th, 2018, 06:31 PM
Planetary Nebula
Hydra
RA 10h 24m 46.1s
DEC −18° 38′ 32.6″
Nebula magnitude: 7.7 (V)
Central star magnitude: 12.1 (V)
Size: 25’
2957
Burness Ansell/Adam Block/AURA/NOAO/NSF
William Herschel discovered NGC 3242 in 1785, and described it this way:
“Beautiful, brilliant, planetary disk ill defined, but uniformly bright, the light of the colour Jupiter…”.
Much later, Admiral William Smyth described it as:
“From its size, equable light, and colour, this fine object resembles Jupiter.”
But the comparison only goes so far – there’s no chance anyone who’s seen Jupiter would mistake 3242 for any planet, much less the brighter and completely different looking gas giant. Unfortunately, this confusing nickname contributed to the ongoing use of the misleading label “planetary nebula” for this class of object.
Although that can be an interesting discussion all its own, it's not the point of this post. I chose spectacular NGC 3242 for this week’s object because I’ve rarely had a good look at it – poor weather and its southerly declination consistently get in my way - but I’ve still managed to get a few decent observations, most notably with my 28-inch and Jimi’s 48-inch scopes.
My most satisfying look through the 28-inch was in April 2012 from Likely Place, California. My notes:
“It’s been a long time since I’ve had a good look at 3242 but this view makes up for lost time. Excellent view at 695x showed some detail at each end of the inner ring, and the faint outer halo was evident at 155x. The annulus between the inner ring and the bright perimeter is brighter on both sides of the middle and darker on the ends. The central star is bright and easy – and seen through the h-beta filter! Dim, but definitely seen, as was the inner ring. 21.76 SQM.
2953 2954
Three years later the view through Jimi’s 48-inch was, of course, even better:
“The Ghost of Jupiter is looking marvelous at 813x – a distinct rim to the perimeter is obvious as are the two ansae on the inner annulus. The outer halo is also well seen as is a dark “moat” between the inner annulus and the rim. An added plus are the two direct vision galaxies in the 488x field of view!" (MAC 1024-1840 and 1024-1842)
2955 2956
What strikes me about both of these observations is the wonderful, and somewhat spooky symmetry of 3242. It barely seems real! The outer halo was surprisingly easy to see, perhaps the brightest outer halo of any planetary. These eyepiece sketches don’t capture the subtle gradations of 3242 all that well, and it has a wonderful silky-smooth texture that's impossible (for me) to capture in a quick pencil sketch.
My notes don’t mention color, and strangely only one of my other observations mentions its strong greenish-blue hue. I think that’s because I quickly went to high magnifications to study the internal detail and I forgot about the color when writing my notes. Does that happen with anyone else?
"GIVE IT A GO AND LET US KNOW"
Hydra
RA 10h 24m 46.1s
DEC −18° 38′ 32.6″
Nebula magnitude: 7.7 (V)
Central star magnitude: 12.1 (V)
Size: 25’
2957
Burness Ansell/Adam Block/AURA/NOAO/NSF
William Herschel discovered NGC 3242 in 1785, and described it this way:
“Beautiful, brilliant, planetary disk ill defined, but uniformly bright, the light of the colour Jupiter…”.
Much later, Admiral William Smyth described it as:
“From its size, equable light, and colour, this fine object resembles Jupiter.”
But the comparison only goes so far – there’s no chance anyone who’s seen Jupiter would mistake 3242 for any planet, much less the brighter and completely different looking gas giant. Unfortunately, this confusing nickname contributed to the ongoing use of the misleading label “planetary nebula” for this class of object.
Although that can be an interesting discussion all its own, it's not the point of this post. I chose spectacular NGC 3242 for this week’s object because I’ve rarely had a good look at it – poor weather and its southerly declination consistently get in my way - but I’ve still managed to get a few decent observations, most notably with my 28-inch and Jimi’s 48-inch scopes.
My most satisfying look through the 28-inch was in April 2012 from Likely Place, California. My notes:
“It’s been a long time since I’ve had a good look at 3242 but this view makes up for lost time. Excellent view at 695x showed some detail at each end of the inner ring, and the faint outer halo was evident at 155x. The annulus between the inner ring and the bright perimeter is brighter on both sides of the middle and darker on the ends. The central star is bright and easy – and seen through the h-beta filter! Dim, but definitely seen, as was the inner ring. 21.76 SQM.
2953 2954
Three years later the view through Jimi’s 48-inch was, of course, even better:
“The Ghost of Jupiter is looking marvelous at 813x – a distinct rim to the perimeter is obvious as are the two ansae on the inner annulus. The outer halo is also well seen as is a dark “moat” between the inner annulus and the rim. An added plus are the two direct vision galaxies in the 488x field of view!" (MAC 1024-1840 and 1024-1842)
2955 2956
What strikes me about both of these observations is the wonderful, and somewhat spooky symmetry of 3242. It barely seems real! The outer halo was surprisingly easy to see, perhaps the brightest outer halo of any planetary. These eyepiece sketches don’t capture the subtle gradations of 3242 all that well, and it has a wonderful silky-smooth texture that's impossible (for me) to capture in a quick pencil sketch.
My notes don’t mention color, and strangely only one of my other observations mentions its strong greenish-blue hue. I think that’s because I quickly went to high magnifications to study the internal detail and I forgot about the color when writing my notes. Does that happen with anyone else?
"GIVE IT A GO AND LET US KNOW"