NGC 918 A pinwheel in the mist

Imbedded links aren't mine. I don't appreciate the emails I've gotten blaming me for the crap SpaceBanter is doing. Yell at them not me. I show my links starting with the standard http or https prefix. If you don't see that don't click on it. Don't support this crap.

NGC 918 is a SAB(rs)c: galaxy in Ares about 60 million light-years distant. It is seen through a lot of dust reducing its brightness by about a magnitude in visual light, more in blue and less in red light which gives it a rather reddish hue. The galaxy hosed SN2009js 5 years ago. There's little known about this galaxy as it is located in the Zone of Avoidance where most galactic studies fear to tread. The southern half seems crossed by parallel bands of stars that are quite evenly spaced. Is this real or caused by dust in our galaxy obscuring it in bands. The POSS 2 IR image shows no hint of these bands which could indicate dust is to blame but if they are made up of hot blue stars then they'd not be seen in IR. The dust we do see in the image is far too diffuse to have created such a fine structure as these bands so I vote for the bands being real but what causes them. Some galaxies obviously interacting with a companion sometimes show bands much like these. M51 would be an example. But this is a very lonely galaxy. It has no companions.

I tried to put a lot of time into this one but I ran into an equipment failure, the 35 year old home built power supply I used to power the dew heater died and I didn't know it. I tried to take 2 hours of luminance and 1 hour for each color to bring out the foreground nebulosity over three nights. These were done after midnight while I was sleeping. I had no idea the power supply had died until a couple days later. The dew shield was sufficient in early evening when I was around to see how it was doing but I'd get up in the morning and "clouds" had ruined the rest of the night. Finally a couple nights later dew was so bad it happened while I was up and the cloud sensor said it was very clear yet I was getting clouded out. I trudged to the observatory muttering things not suitable for this post and found the fogged corrector and dead power supply. I unplugged it (no switch) that somehow blew the fuze for the isolation transformer that powers everything. Now you really don't want to know what I was screaming rather than muttering. Of course it takes a micro fuse I didn't have nor does anyone local. By the time I was up and running again I never was able to reshoot this object. I had to pull the boat early from the lake and use its (spam) battery plus trickle charger to run until I got a new power supply and run without the isolation transformer which isolates me from some nasty power issues deep in the northern woods.

The result was of the three nights of luminance data the first night had great seeing but hit by dew. The color data was useless. Second night seeing was poor but dew issue light so both luminance and color were usable. The third night was dewed out completely.

The field was full of asteroids. If not for them I'd not do an annotated image as only NGC 918 had redshift data at NED. But combining two nights of luminance data turned up 12 different asteroids with 13 asteroid annotations on the image. How 12 became 13 is that one and only one was in the frames of both nights, (117336) 2004 XP15 (Link is spam having nothing to do with astronomy it's bullcrap). Only one has a name (9682) Gravesande. Its naming citation reads: "Willem J. 's Gravesande (1688-1742) was a professor of mathematics, astronomy and philosophy at Leiden University. During his life he wrote many textbooks on mathematics and philosophy, and he is also important as an exponent of Newton's philosophy in Europe. The name was suggested by W. A. Fröger." The 's is not a misprint that is his part of his sir name, 's Gravesande. The J is for Jacob in case you were wondering. The asteroids in the first night's frames have no color data. The brightest on the second night do. This is why some brighter ones have color trails and some don't.

This is yet another for the redo list on a better night.

14" LX200R @ f/10, L=8x10' RGB=2x10', STL-11000XM, Paramount ME

Rick

I see now the nebulosity is part of a large cloud known as MBM 8. This cloud extends several degrees in also includes Arp 276. I took that one in 2009 and reprocessed it in 2011 which I can't find I ever posted. Since it is seen through part of the same molecular cloud (1.25 degrees northeast of NGC 918) here's that image using only 4 luminance frames thanks to much better conditions.

Rick

Rick,

what a variety of object, a galaxy, galactic dust and a swarm of
asteroids...
Too bad you lost so much time on the power issue. Could have done one or two
additional objects in that time.

Stefan


"WA0CKY" schrieb im Newsbeitrag ...


NGC 918 is a SAB(rs)c: galaxy in Ares about 60 million light-years
distant. It is seen through a lot of dust reducing its brightness by
about a magnitude in visual light, more in blue and less in red light
which gives it a rather reddish hue. The galaxy hosed SN2009js 5 years
ago. There's little known about this galaxy as it is located in the Zone
of Avoidance where most galactic studies fear to tread. The southern
half seems crossed by parallel bands of stars that are quite evenly
spaced. Is this real or caused by dust in our galaxy obscuring it in
bands. The POSS 2 IR image shows no hint of these bands which could
indicate dust is to blame but if they are made up of hot blue stars then
they'd not be seen in IR. The dust we do see in the image is far too
diffuse to have created such a fine structure as these bands so I vote
for the bands being real but what causes them. Some galaxies obviously
interacting with a companion sometimes show bands much like these. M51
would be an example. But this is a very lonely galaxy. It has no
companions.

I tried to put a lot of time into this one but I ran into an equipment
failure, the 35 year old home built power supply I used to power the dew
heater died and I didn't know it. I tried to take 2 hours of luminance
and 1 hour for each color to bring out the foreground nebulosity over
three nights. These were done after midnight while I was sleeping. I
had no idea the power supply had died until a couple days later. The
dew shield was sufficient in early evening when I was around to see how
it was doing but I'd get up in the morning and "clouds" had ruined the
rest of the night. Finally a couple nights later dew was so bad it
happened while I was up and the cloud sensor said it was very clear yet
I was getting clouded out. I trudged to the observatory muttering
things not suitable for this post and found the fogged corrector and
dead power supply. I unplugged it (no switch) that somehow blew the
fuze for the isolation transformer that powers everything. Now you
really don't want to know what I was screaming rather than muttering.
Of course it takes a micro fuse I didn't have nor does anyone local. By
the time I was up and running again I never was able to reshoot this
object. I had to pull the boat early from the lake and use its battery
plus trickle charger to run until I got a new power supply and run
without the isolation transformer which isolates me from some nasty
power issues deep in the north woods.

The result was of the three nights of luminance data the first night had
great seeing but hit by dew. The color data was useless. Second night
seeing was poor but dew issue light so both luminance and color were
usable. The third night was dewed out completely.

The field was full of asteroids. If not for them I'd not do an
annotated image as only NGC 918 had redshift data at NED. But combining
two nights of luminance data turned up 12 different asteroids with 13
asteroid annotations on the image. How 12 became 13 is that one and
only one was in the frames of both nights, (117336) 2004 XP15. Only one
has a name (9682) Gravesande. Its naming citation reads: "Willem J. 's
Gravesande (1688-1742) was a professor of mathematics, astronomy and
philosophy at Leiden University. During his life he wrote many
textbooks on mathematics and philosophy, and he is also important as an
exponent of Newton's philosophy in Europe. The name was suggested by W.
A. Fröger." The 's is not a misprint that is his part of his sir name,
's Gravesande. The J is for Jacob in case you were wondering. The
asteroids in the first night's frames have no color data. The brightest
on the second night do. This is why some brighter ones have color
trails and some don't.

This is yet another for the redo list on a better night.

14" LX200R @ f/10, L=8x10' RGB=2x10', STL-11000XM, Paramount ME

Rick


--
WA0CKY