ASTRO: NGC 271 a somewhat messed up barred spiral

NGC 271 is a somewhat distorted, face on spiral in Cetus. It's redshift
distance is a bit over 170 million light-years. Tully-Fisher
measurements (all from the same data) range from 191 to 220 million
light-years depending on how you look at that data. The value with the
smallest error bar says 191 million light-years while a median value is
218 million. Pick your candidate or roll your own.

Off the southeast edge of the galaxy is a puff of stars. The arm had
pretty well faded out then returns in this puff or is it a separate
object? NED offers no help here. I note the other arm on the other
side also fades then reappears though looks again like the arm rather
than a puff. Still It is likely it is just part of the arm.

SAO 128981 is an 8th magnitude star that gives trouble here. It's glare
overrides the galaxy. Could that create a false sense of the drop in
the arm's intensity creating the appearance of a puff? I don't think
so, the drop off was quite obvious even through the glare of the star.
I find no amateur images of this one but the various POSS images and the
Sloan image all are bothered by the star but also appear to show the
puff as real.

This area of the sky hasn't been well studied for galaxies. I found
only 3 others with redshift data. One, to the southwest has a similar
redshift and is likely a companion. The other two were about a billion
light-years out. Out of frame at the top right is UGC 00505 also at
about the same redshift as NGC 271. Some sources list these three as a
triple. The odd shape of NGC 271 might be due to interaction with UGC
00505. For reasons I can't determine I managed to not get it in the
frame. My notes say to catch it yet I didn't.

NGC 271 was discovered by William Herschel in 1785 and at magnitude 12.2
moderately bright in a 10" scope. Yet it isn't in either of the
Herschel 400 observing program lists.

One of the galaxies with redshift, in the lower left is a face on spiral
with featureless arms at my resolution. It is a rare galaxy in that it
is both a strong IR source and a Ultraviolet Excess source. Hence I
included both its 2MASS and GALEX designations.

Preparing an annotated image, especially in poorly covered areas like
this results in lots of issues. A SCT scope can create ghost images
that look much like faint dwarf galaxies. These I usually process out.
Since several have asked me recently about them I left in the one that
is in this image. It's above the 2MASS/GALEX galaxy. In well covered
fields they are easy to spot as they are not in the various catalogs.
But in a region like this where most are unlisted things get more
difficult. They are faint and thus their absence from the POSS plates
may not mean they aren't real. I have to download the FITS and then
stretch like crazy. I also get the Sloan image when available (often
not the case in these regions) and do the same. In this case the Sloan
image is available. Neither it nor the POSS images show any sign of it
so it is quite likely not real. But at the top center of my image is a
similar faint smudge that is real and in this case listed in NED though
that is rare in fields like this one. It is [dIM97] J005019.82-014447.4.
It shows how similar a real low surface brightness galaxy is to a
ghost image the SCT corrector can create having a flat surface ideal for
reflections. The odd linear feature towards its southern edge is a pair
of faint stars not part of that galaxy. NED had no redshift for it so
that is shown by "na".

Another issue is shown by the galaxy to the lower left, MCG +00-03-016.
NED has no distance for it yet labels it a dwarf. In other images
I've seen similar "dwarfs" with a redshift value of over a billion
light-years. Now you can't be a dwarf when 100,000 light-years across
that these have to be or at a very bright magnitude as others can be.
Something is wrong in these cases. But when there's no distance data is
it really a dwarf or just another that isn't what is claimed? This one
sure does look like it could be a dwarf so I didn't add a question mark
but still I can't be certain that's the case after all the obvious
errors I've seen in other fields.

Why some galaxies don't make a catalog and others do always amazes me.
APMUKS(BJ) B004829.03-021415.6 is a galaxy in the Automated Plate
Measurement UK survey. Just to its north is a galaxy that for some
reason wasn't seen by the survey. Seems automation misses the rather
obvious sometimes. Another reason by the various Galaxy Zoo projects
are finding so much not found by the computers.

The annotated image is sparse as few galaxies in the image had red shift
values. I've labeled others without redshift data when mentioned above.
Hundreds of others missed their 15 minutes of fame it seems.

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

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

Great detail Rick.
I have put NGC 271 on my list although it is too low to clear my local
horizon until it is well past meridian.

Stefan


"Rick Johnson" schrieb im Newsbeitrag
...

NGC 271 is a somewhat distorted, face on spiral in Cetus. It's redshift
distance is a bit over 170 million light-years. Tully-Fisher
measurements (all from the same data) range from 191 to 220 million
light-years depending on how you look at that data. The value with the
smallest error bar says 191 million light-years while a median value is
218 million. Pick your candidate or roll your own.

Off the southeast edge of the galaxy is a puff of stars. The arm had
pretty well faded out then returns in this puff or is it a separate
object? NED offers no help here. I note the other arm on the other
side also fades then reappears though looks again like the arm rather
than a puff. Still It is likely it is just part of the arm.

SAO 128981 is an 8th magnitude star that gives trouble here. It's glare
overrides the galaxy. Could that create a false sense of the drop in
the arm's intensity creating the appearance of a puff? I don't think
so, the drop off was quite obvious even through the glare of the star.
I find no amateur images of this one but the various POSS images and the
Sloan image all are bothered by the star but also appear to show the
puff as real.

This area of the sky hasn't been well studied for galaxies. I found
only 3 others with redshift data. One, to the southwest has a similar
redshift and is likely a companion. The other two were about a billion
light-years out. Out of frame at the top right is UGC 00505 also at
about the same redshift as NGC 271. Some sources list these three as a
triple. The odd shape of NGC 271 might be due to interaction with UGC
00505. For reasons I can't determine I managed to not get it in the
frame. My notes say to catch it yet I didn't.

NGC 271 was discovered by William Herschel in 1785 and at magnitude 12.2
moderately bright in a 10" scope. Yet it isn't in either of the
Herschel 400 observing program lists.

One of the galaxies with redshift, in the lower left is a face on spiral
with featureless arms at my resolution. It is a rare galaxy in that it
is both a strong IR source and a Ultraviolet Excess source. Hence I
included both its 2MASS and GALEX designations.

Preparing an annotated image, especially in poorly covered areas like
this results in lots of issues. A SCT scope can create ghost images
that look much like faint dwarf galaxies. These I usually process out.
Since several have asked me recently about them I left in the one that
is in this image. It's above the 2MASS/GALEX galaxy. In well covered
fields they are easy to spot as they are not in the various catalogs.
But in a region like this where most are unlisted things get more
difficult. They are faint and thus their absence from the POSS plates
may not mean they aren't real. I have to download the FITS and then
stretch like crazy. I also get the Sloan image when available (often
not the case in these regions) and do the same. In this case the Sloan
image is available. Neither it nor the POSS images show any sign of it
so it is quite likely not real. But at the top center of my image is a
similar faint smudge that is real and in this case listed in NED though
that is rare in fields like this one. It is [dIM97] J005019.82-014447.4.
It shows how similar a real low surface brightness galaxy is to a
ghost image the SCT corrector can create having a flat surface ideal for
reflections. The odd linear feature towards its southern edge is a pair
of faint stars not part of that galaxy. NED had no redshift for it so
that is shown by "na".

Another issue is shown by the galaxy to the lower left, MCG +00-03-016.
NED has no distance for it yet labels it a dwarf. In other images
I've seen similar "dwarfs" with a redshift value of over a billion
light-years. Now you can't be a dwarf when 100,000 light-years across
that these have to be or at a very bright magnitude as others can be.
Something is wrong in these cases. But when there's no distance data is
it really a dwarf or just another that isn't what is claimed? This one
sure does look like it could be a dwarf so I didn't add a question mark
but still I can't be certain that's the case after all the obvious
errors I've seen in other fields.

Why some galaxies don't make a catalog and others do always amazes me.
APMUKS(BJ) B004829.03-021415.6 is a galaxy in the Automated Plate
Measurement UK survey. Just to its north is a galaxy that for some
reason wasn't seen by the survey. Seems automation misses the rather
obvious sometimes. Another reason by the various Galaxy Zoo projects
are finding so much not found by the computers.

The annotated image is sparse as few galaxies in the image had red shift
values. I've labeled others without redshift data when mentioned above.
Hundreds of others missed their 15 minutes of fame it seems.

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

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