NGC 3198 Big Grand Design Spiral

NGC 3198 is a classic spiral galaxy in southern Ursa Major near the
western back foot. Recent Cepheid measurements by the HST put it at
47.3 million light-years from earth. The redshift would indicate 41
million light-years so there is some agreement. Though NED lists some
17 other Cepheid measurements from earth based scope that give values
from 36.5 to 57.4 million light-years. But their average comes back to
47 million light-years so I'll go with the HST project's determination.
The HST image of part of the galaxy is at:
http://upload.wikimedia.org/wikipedi...le_WikiSky.jpg

I imaged this one just because I never had imaged it before and because
I thought I spotted an interesting distant galaxy cluster in the POSS
plates to the west northwest of NGC 3198. It is the cluster WHL
J101858.1+453618 listed at 4.4 billion light-years. It is marked by GC
4.4 in the annotated image. NED shows it containing 21 galaxies. Many
of these appear to be visible in my image. The position seems to be
that of the largest and brightest member though it is shown to have a
distance of only 4.0 billion light-years. Though both are photographic
estimates. These give a ball park figure at best so the difference
isn't all that surprising.

Due to wanting to try to pick up members of this cluster I doubled my
normal luminosity time. Instead of my normal 22.5 limiting magnitude
this one goes far deeper. The quasar southwest of the NGC 3198 at 12.4
billion light-years is listed at magnitude 23.2.

Down in the lower left corner is a Blazar (BLZR). These are quasars in
which the relativistic jet is pointed right at us. This causes rapid
fluctuations in brightness. This also makes it a BRLG. This stands for
Bright Radio Line Galaxy as seen by radio telescopes. This is a rather
nearby one so bright and earned 29 separate designations in NED! I'll
use the first one, B3 1018+456. Enter that in NED to see the rest.

In the lower right corner is a small, very fuzzy blue blob of a galaxy.
It has a red shift that puts it about the same distance as far large
NGC 3198, only 44 million light-years away. It must be some sort of
dwarf Magellanic galaxy. NED lists its largest diameter at 0.32 minutes
which would give it a size of on 4100 light year. NGC 3198's diameter
is 8.5 minutes. At 47 million light-years that would give a diameter of
116,000 light-years, about the size of our galaxy.

Anyone following my posts knows I keep finding, usually blue, galaxies
not listed in NED even though many far fainter ones are. This image
will be no exception. Toward the upper left, below a rather bright,
white, star is such a blue galaxy. As usual, it is marked with a
question mark. I just scanned the annotated image for blue galaxies not
listed. It was the first one I tried! That caused me to try some more.
Next 4 were listed at NED, just without redshift data. That's fine.
But then the next one was another miss. It too is below a rather white
star, though well below it. Look to the northwest, left of the galaxy
cluster at 4.4 billion light-years. I quit looking after that.

14" LX200R @ f/10, L=8x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

Lots of detail in this galaxy.
The limiting mag is amazing, I remember times when the large professional
observatories could not get past mag24...

Stefan

"Rick Johnson" schrieb im Newsbeitrag
. com...
NGC 3198 is a classic spiral galaxy in southern Ursa Major near the
western back foot. Recent Cepheid measurements by the HST put it at
47.3 million light-years from earth. The redshift would indicate 41
million light-years so there is some agreement. Though NED lists some
17 other Cepheid measurements from earth based scope that give values
from 36.5 to 57.4 million light-years. But their average comes back to
47 million light-years so I'll go with the HST project's determination.
The HST image of part of the galaxy is at:
http://upload.wikimedia.org/wikipedi...le_WikiSky.jpg

I imaged this one just because I never had imaged it before and because
I thought I spotted an interesting distant galaxy cluster in the POSS
plates to the west northwest of NGC 3198. It is the cluster WHL
J101858.1+453618 listed at 4.4 billion light-years. It is marked by GC
4.4 in the annotated image. NED shows it containing 21 galaxies. Many
of these appear to be visible in my image. The position seems to be
that of the largest and brightest member though it is shown to have a
distance of only 4.0 billion light-years. Though both are photographic
estimates. These give a ball park figure at best so the difference
isn't all that surprising.

Due to wanting to try to pick up members of this cluster I doubled my
normal luminosity time. Instead of my normal 22.5 limiting magnitude
this one goes far deeper. The quasar southwest of the NGC 3198 at 12.4
billion light-years is listed at magnitude 23.2.

Down in the lower left corner is a Blazar (BLZR). These are quasars in
which the relativistic jet is pointed right at us. This causes rapid
fluctuations in brightness. This also makes it a BRLG. This stands for
Bright Radio Line Galaxy as seen by radio telescopes. This is a rather
nearby one so bright and earned 29 separate designations in NED! I'll
use the first one, B3 1018+456. Enter that in NED to see the rest.

In the lower right corner is a small, very fuzzy blue blob of a galaxy.
It has a red shift that puts it about the same distance as far large
NGC 3198, only 44 million light-years away. It must be some sort of
dwarf Magellanic galaxy. NED lists its largest diameter at 0.32 minutes
which would give it a size of on 4100 light year. NGC 3198's diameter
is 8.5 minutes. At 47 million light-years that would give a diameter of
116,000 light-years, about the size of our galaxy.

Anyone following my posts knows I keep finding, usually blue, galaxies
not listed in NED even though many far fainter ones are. This image
will be no exception. Toward the upper left, below a rather bright,
white, star is such a blue galaxy. As usual, it is marked with a
question mark. I just scanned the annotated image for blue galaxies not
listed. It was the first one I tried! That caused me to try some more.
Next 4 were listed at NED, just without redshift data. That's fine.
But then the next one was another miss. It too is below a rather white
star, though well below it. Look to the northwest, left of the galaxy
cluster at 4.4 billion light-years. I quit looking after that.

14" LX200R @ f/10, L=8x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

I've hit about 24.5 a time or two, like when imaging gravitational arcs
in Abell 2218. That used 2 hours of L. While my typical processed
image limit at 40 minutes is 22.5 they often go past 23.5 in the FITS
stack. I've never understood it but adding color does seem to cut about
a half magnitude off the processed image. Limiting noise costs more.

In my 2415 film days 18.5 was about my limit in the 10" f/5. So going
this faint surprised me. Especially considering the 11K chip is one of
the least quantum efficient mono chips out there. The ST-7 I have has
more quantum efficiency, about 60% more in fact yet I don't really see
much difference in limiting magnitude. It just gets there faster.

Rick


On 3/21/2012 3:43 PM, Stefan Lilge wrote:
Lots of detail in this galaxy.
The limiting mag is amazing, I remember times when the large professional
observatories could not get past mag24...

Stefan

"Rick schrieb im Newsbeitrag
. com...
NGC 3198 is a classic spiral galaxy in southern Ursa Major near the
western back foot. Recent Cepheid measurements by the HST put it at
47.3 million light-years from earth. The redshift would indicate 41
million light-years so there is some agreement. Though NED lists some
17 other Cepheid measurements from earth based scope that give values
from 36.5 to 57.4 million light-years. But their average comes back to
47 million light-years so I'll go with the HST project's determination.
The HST image of part of the galaxy is at:
http://upload.wikimedia.org/wikipedi...le_WikiSky.jpg

I imaged this one just because I never had imaged it before and because
I thought I spotted an interesting distant galaxy cluster in the POSS
plates to the west northwest of NGC 3198. It is the cluster WHL
J101858.1+453618 listed at 4.4 billion light-years. It is marked by GC
4.4 in the annotated image. NED shows it containing 21 galaxies. Many
of these appear to be visible in my image. The position seems to be
that of the largest and brightest member though it is shown to have a
distance of only 4.0 billion light-years. Though both are photographic
estimates. These give a ball park figure at best so the difference
isn't all that surprising.

Due to wanting to try to pick up members of this cluster I doubled my
normal luminosity time. Instead of my normal 22.5 limiting magnitude
this one goes far deeper. The quasar southwest of the NGC 3198 at 12.4
billion light-years is listed at magnitude 23.2.

Down in the lower left corner is a Blazar (BLZR). These are quasars in
which the relativistic jet is pointed right at us. This causes rapid
fluctuations in brightness. This also makes it a BRLG. This stands for
Bright Radio Line Galaxy as seen by radio telescopes. This is a rather
nearby one so bright and earned 29 separate designations in NED! I'll
use the first one, B3 1018+456. Enter that in NED to see the rest.

In the lower right corner is a small, very fuzzy blue blob of a galaxy.
It has a red shift that puts it about the same distance as far large
NGC 3198, only 44 million light-years away. It must be some sort of
dwarf Magellanic galaxy. NED lists its largest diameter at 0.32 minutes
which would give it a size of on 4100 light year. NGC 3198's diameter
is 8.5 minutes. At 47 million light-years that would give a diameter of
116,000 light-years, about the size of our galaxy.

Anyone following my posts knows I keep finding, usually blue, galaxies
not listed in NED even though many far fainter ones are. This image
will be no exception. Toward the upper left, below a rather bright,
white, star is such a blue galaxy. As usual, it is marked with a
question mark. I just scanned the annotated image for blue galaxies not
listed. It was the first one I tried! That caused me to try some more.
Next 4 were listed at NED, just without redshift data. That's fine.
But then the next one was another miss. It too is below a rather white
star, though well below it. Look to the northwest, left of the galaxy
cluster at 4.4 billion light-years. I quit looking after that.

14" LX200R @ f/10, L=8x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net