ASTRO: Arp 94

Arp 94 is listed under Arp's category for spiral galaxies with
elliptical galaxies on a arm. It is located less than a degree east of
Gamma Leonis so is very easy to find and is about 68 million light-years
away. It consists of two "big and bright" interacting galaxies; NGC
3226 to the north and 3227 to the south. The pair are quite easily seen
in my 10" scope and likely a 6" should so them as well. Besides being
in Arp's list they are also in the Herschel 400 list, another list I'm
slowly trying to image so this one kills two birds with one image.

There are several other galaxies in the image at about the same distance
as Arp 94. All are far smaller however. NGC 3226 is classed as E2 pec
by NED and simply E by the NGC project. It has an AGN at its heart and
is classed as both a LINER and Seyfert 3 galaxy. NGC 3227 is classed
SAB(s) pec by NED and simply Sb by the NGC project. It is a Seyfert 1.5
galaxy so also has an AGN at its core. So one sees it as a barred
spiral and the other as having no bar. I see it as a mess. The motor
oil colored dust patch on its west side would seem to indicate a lot of
its dust and gas is being ripped from it by the interaction. If they
merge a large elliptical galaxy will likely result.

This is a reshoot. I'd hoped to pick up more of its plumes but didn't
go much deeper this time than before. This one needs a far better night
than I had the two nights I shot it this time. I wasn't happy with the
first round and wanted a lot more time on it. But the skies were rather
uncooperative. I only got twice the data under poor skies. Still I
think it came out better than the first time with half the data but not
by a lot. Difference may be more in improved processing skills as the
stacked FITS look very similar. Unfortunately they were framed rather
differently and I'd lose too much of the field if I combined the data so
just used the new data.

I didn't do an annotated image the first time so that's another reason
for posting the reshoot.

In the annotated image there is one other NGC galaxy, NGC 3222. It too
has very different classifications. NED says SB0 while the NGC project
says E-S0. It is located 4 times further away than Arp 94. Below it is
a group of galaxies at 540-550 million light-years. It contains two
interacting galaxies but Arp missed including this pair. NPM1G +20.0234
is on the right and seems rather normal while SDSS J102247.38+194730.2
on the left has a huge plume. Quite a few galaxies are in the area that
have no redshift data. I presume at least some of these are also members
of this group. While the group seems obvious NED shows no group at this
location. There are 5 groups in the image that NED does mention
however. All much further away.

GMBCG J155.93619+19.80272 has 11 members and is 4.4 billion light-years
away.
GMBCG J155.72679+19.85862 has 10 members at a distance of 4.2 billion
light-years.
GMBCG J156.04999+19.79241 has 9 members at 3.2 billion light-years.
GMBCG J155.61002+19.91511 has 9 members at 4.5 billion light-years.
All of the above have an anchoring galaxy at the same location and
distance as the cluster.
WHL J102402.5+194501 with 7 members at 5.2 billion light-years has a
position one second of arc below that of what may be its BCG. No
redshift is provided for that galaxy however.

There are two asteroids in the image but 4 asteroid trails. This is
because the image was taken over two nights, March 27 and March 28,
2011. The asteroids were slow moving and far enough from the edge to be
in frame both nights. They a
(32073) 2000 JT61 at magnitude 18.4 and (157849) 1998 SH96 at magnitude
19.4 as estimated by the minor planet center. On the second night
(157849) 1998 SH96 moved into the glow of NGC 3222 but can still be
seen. Brighter (32073) 2000 JT61 was on the east side of Arp 94 the
first night and moving out of its glow on the west side the second
night. Thanks to the background glow of the galaxies the color frames
show up somewhat. Usually those are against such a dark sky there is
nothing there in the luminance image and they are not seen.

You will see a quasar marked with a question mark southeast of Arp 94.
NED says it is a star or a galaxy but shows it as a point source with a
redshift of 11.6 billion light-years light travel time. There's no way
I'd pick up a star or galaxy at that distance. So I went against
authority and marked it as a quasar but added the question mark to
indicate there's a question about this one.

There are some other objects marked with a question mark as well but no
identification. I'm certain all are galaxies as I looked at each on on
the Sloan Survey images to verify they were real. I did this because
NED doesn't list them. Likely many others deserve a question mark,
these are just the ones I looked at to find redshift data and found not
only no redshift data but no galaxy either! About 21% of those I
checked were missing yet NED shows over 3000 objects in this image. I
don't know why these were omitted. I'm used to finding one and one time
2 missing from NED this way but 4 is a record. There are likely more as
my sample size was only 19. The one due west of NGC 3226 is one of a
pair of galaxies. The fainter one is listed but with no redshift. The
brighter is totally missing. Below it and a bit east is another pair, a
bit further apart. Again the faint one made NED the brighter did not.
There was another pair in which the fainter member wasn't listed but
even after consulting the Sloan image I was uncertain it it was a star
or galaxy. It is among a group of 6 galaxies (5 if it is a star) all
overlapping making identification difficult. Look for the galaxy at 2.4
billion light-years southeast of NGC 3222. It is orange with a small
object beside it on the east. In the Sloan image it is several galaxies
plus this object. A couple of the galaxies are seen in my image but most
just add to the fuzz around it. Its position is 10h 22m 47.84s +19d 50'
53" for those wanting to look it up at the Sloan site:
http://skyserver.sdss3.org/dr8/en/tools/chart/chart.asp

14" LX200R @ f/10, L=9x10' RGB=4x10'x3, STL-11000XM, Paramount ME

Rick

--
Prefix is correct. Domain is arvig dot net

I see I attached the wrong cropped image. I meant to attach the one enlarged to 0.80" per pixel.

Rick
--
Prefix is correct. Domain is arvig dot net[/quote]

Mighty image Rick.
I have never seen so much detail in this couple.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
. com...

Arp 94 is listed under Arp's category for spiral galaxies with
elliptical galaxies on a arm. It is located less than a degree east of
Gamma Leonis so is very easy to find and is about 68 million light-years
away. It consists of two "big and bright" interacting galaxies; NGC
3226 to the north and 3227 to the south. The pair are quite easily seen
in my 10" scope and likely a 6" should so them as well. Besides being
in Arp's list they are also in the Herschel 400 list, another list I'm
slowly trying to image so this one kills two birds with one image.

There are several other galaxies in the image at about the same distance
as Arp 94. All are far smaller however. NGC 3226 is classed as E2 pec
by NED and simply E by the NGC project. It has an AGN at its heart and
is classed as both a LINER and Seyfert 3 galaxy. NGC 3227 is classed
SAB(s) pec by NED and simply Sb by the NGC project. It is a Seyfert 1.5
galaxy so also has an AGN at its core. So one sees it as a barred
spiral and the other as having no bar. I see it as a mess. The motor
oil colored dust patch on its west side would seem to indicate a lot of
its dust and gas is being ripped from it by the interaction. If they
merge a large elliptical galaxy will likely result.

This is a reshoot. I'd hoped to pick up more of its plumes but didn't
go much deeper this time than before. This one needs a far better night
than I had the two nights I shot it this time. I wasn't happy with the
first round and wanted a lot more time on it. But the skies were rather
uncooperative. I only got twice the data under poor skies. Still I
think it came out better than the first time with half the data but not
by a lot. Difference may be more in improved processing skills as the
stacked FITS look very similar. Unfortunately they were framed rather
differently and I'd lose too much of the field if I combined the data so
just used the new data.

I didn't do an annotated image the first time so that's another reason
for posting the reshoot.

In the annotated image there is one other NGC galaxy, NGC 3222. It too
has very different classifications. NED says SB0 while the NGC project
says E-S0. It is located 4 times further away than Arp 94. Below it is
a group of galaxies at 540-550 million light-years. It contains two
interacting galaxies but Arp missed including this pair. NPM1G +20.0234
is on the right and seems rather normal while SDSS J102247.38+194730.2
on the left has a huge plume. Quite a few galaxies are in the area that
have no redshift data. I presume at least some of these are also members
of this group. While the group seems obvious NED shows no group at this
location. There are 5 groups in the image that NED does mention
however. All much further away.

GMBCG J155.93619+19.80272 has 11 members and is 4.4 billion light-years
away.
GMBCG J155.72679+19.85862 has 10 members at a distance of 4.2 billion
light-years.
GMBCG J156.04999+19.79241 has 9 members at 3.2 billion light-years.
GMBCG J155.61002+19.91511 has 9 members at 4.5 billion light-years.
All of the above have an anchoring galaxy at the same location and
distance as the cluster.
WHL J102402.5+194501 with 7 members at 5.2 billion light-years has a
position one second of arc below that of what may be its BCG. No
redshift is provided for that galaxy however.

There are two asteroids in the image but 4 asteroid trails. This is
because the image was taken over two nights, March 27 and March 28,
2011. The asteroids were slow moving and far enough from the edge to be
in frame both nights. They a
(32073) 2000 JT61 at magnitude 18.4 and (157849) 1998 SH96 at magnitude
19.4 as estimated by the minor planet center. On the second night
(157849) 1998 SH96 moved into the glow of NGC 3222 but can still be
seen. Brighter (32073) 2000 JT61 was on the east side of Arp 94 the
first night and moving out of its glow on the west side the second
night. Thanks to the background glow of the galaxies the color frames
show up somewhat. Usually those are against such a dark sky there is
nothing there in the luminance image and they are not seen.

You will see a quasar marked with a question mark southeast of Arp 94.
NED says it is a star or a galaxy but shows it as a point source with a
redshift of 11.6 billion light-years light travel time. There's no way
I'd pick up a star or galaxy at that distance. So I went against
authority and marked it as a quasar but added the question mark to
indicate there's a question about this one.

There are some other objects marked with a question mark as well but no
identification. I'm certain all are galaxies as I looked at each on on
the Sloan Survey images to verify they were real. I did this because
NED doesn't list them. Likely many others deserve a question mark,
these are just the ones I looked at to find redshift data and found not
only no redshift data but no galaxy either! About 21% of those I
checked were missing yet NED shows over 3000 objects in this image. I
don't know why these were omitted. I'm used to finding one and one time
2 missing from NED this way but 4 is a record. There are likely more as
my sample size was only 19. The one due west of NGC 3226 is one of a
pair of galaxies. The fainter one is listed but with no redshift. The
brighter is totally missing. Below it and a bit east is another pair, a
bit further apart. Again the faint one made NED the brighter did not.
There was another pair in which the fainter member wasn't listed but
even after consulting the Sloan image I was uncertain it it was a star
or galaxy. It is among a group of 6 galaxies (5 if it is a star) all
overlapping making identification difficult. Look for the galaxy at 2.4
billion light-years southeast of NGC 3222. It is orange with a small
object beside it on the east. In the Sloan image it is several galaxies
plus this object. A couple of the galaxies are seen in my image but most
just add to the fuzz around it. Its position is 10h 22m 47.84s +19d 50'
53" for those wanting to look it up at the Sloan site:
http://skyserver.sdss3.org/dr8/en/tools/chart/chart.asp

14" LX200R @ f/10, L=9x10' RGB=4x10'x3, STL-11000XM, Paramount ME

Rick

--
Prefix is correct. Domain is arvig dot net