ASTRO: NGC 4631

NGC 4361 in a rather famous planetary in the quadrilateral of Corvus.
The central star sits in a dark hole in the planetary. That isn't a
processing artifact. The hole is real. I was unable to find any source
for a distance to it other than one reference to 2500 light-years that
gave no indication where the estimate came from. While Spitzer has
imaged it their text has no mention of distance. I suspect they would
if there was any reliable estimate available. APOD and others similarly
avoid even mentioning distance.
http://www.spitzer.caltech.edu/image...ebula-NGC-4361

There are several galaxies in my image (you didn't expect me to not
mention them) but again no distance data is available for them either.
The area isn't in the Sloan survey. The obvious spindle galaxy to the
northwest of NGC 4361 is 2MASX J12242187-1841381. The few others in the
image NED catalogs are all from this catalog.

Since the planetary when seen in black and white photos shows a spiral
shape rather like a distorted spiral galaxy with a bright core there
have been tales of astronomy instructors slipping it into an exercise
for the students to classify galaxies. None give specifics so this is
probably just a tale. I'll admit that when I first brought up a raw
luminance image to see about my note to retake it, I was in the middle
of processing galaxies. My brain first saw it as a galaxy until the
4361 registered in my brain. At that point I was thinking I'd
misidentified the image and it really was a galaxy. So this tale
certainly sounds possible.

At -18.75 degrees it is down in my gunk and below my normal imaging
limits. I gave it a try anyway last March. But the results were so bad
I marked it retake. Still I decided to give a try at pulling something
out of the data. Blue was severely scattered by both ice in the air
over the lake as well as normal atmospheric scattering. Thus my usual
formulas for compensating for atmospheric scattering alone greatly under
compensated. With a lot of trial and error I think I have a reasonable
color balance. Seeing was a bit worse than 3" so the image is rather
fuzzy. Still it is better than I expected. Unless I get an exceptional
night I'll likely not try again.

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

A fellow in my astronomy club has been after me for 6 years to image
this one. Took that long to get a night good enough to go that low.
Doesn't happen very often here. I could go to this altitude in NE and
the skies held fairly well. Up here seeing is a disaster at that same
altitude. In Nebraska I could go down to about -30 declination. Since
I'm 7 degrees further north that should translate to -23 degrees but
even -15 is far worse than I had at -30 down there. Not sure why, might
be down that low I'm looking over forest and lake alternating many times
in a few dozen miles. Forests cool fast, lakes are same temperature day
and night. This might be a seeing disaster that can extend up to 0
declination many nights. All I can think of that is different here. In
Nebraska I did have a lake about a mile and half south though here I'm
only 130 feet from the lake shore. Still Great Bear Solar Observatory
is in the middle of a lake for the great seeing it offers. They have no
shore though. Just water right outside the southern side of the
observatory. Doubt the DNR would allow me to put it over the lake.

Rick

On 2/20/2011 5:59 AM, Stefan Lilge wrote:
Beautiful image Rick. I don't even have it on my list as it is too low...

Stefan

"Rick schrieb im Newsbeitrag
ter.com...
NGC 4361 in a rather famous planetary in the quadrilateral of Corvus.
The central star sits in a dark hole in the planetary. That isn't a
processing artifact. The hole is real. I was unable to find any source
for a distance to it other than one reference to 2500 light-years that
gave no indication where the estimate came from. While Spitzer has
imaged it their text has no mention of distance. I suspect they would
if there was any reliable estimate available. APOD and others similarly
avoid even mentioning distance.
http://www.spitzer.caltech.edu/image...ebula-NGC-4361

There are several galaxies in my image (you didn't expect me to not
mention them) but again no distance data is available for them either.
The area isn't in the Sloan survey. The obvious spindle galaxy to the
northwest of NGC 4361 is 2MASX J12242187-1841381. The few others in the
image NED catalogs are all from this catalog.

Since the planetary when seen in black and white photos shows a spiral
shape rather like a distorted spiral galaxy with a bright core there
have been tales of astronomy instructors slipping it into an exercise
for the students to classify galaxies. None give specifics so this is
probably just a tale. I'll admit that when I first brought up a raw
luminance image to see about my note to retake it, I was in the middle
of processing galaxies. My brain first saw it as a galaxy until the
4361 registered in my brain. At that point I was thinking I'd
misidentified the image and it really was a galaxy. So this tale
certainly sounds possible.

At -18.75 degrees it is down in my gunk and below my normal imaging
limits. I gave it a try anyway last March. But the results were so bad
I marked it retake. Still I decided to give a try at pulling something
out of the data. Blue was severely scattered by both ice in the air
over the lake as well as normal atmospheric scattering. Thus my usual
formulas for compensating for atmospheric scattering alone greatly under
compensated. With a lot of trial and error I think I have a reasonable
color balance. Seeing was a bit worse than 3" so the image is rather
fuzzy. Still it is better than I expected. Unless I get an exceptional
night I'll likely not try again.

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".