ASTRO: Arp 13

Many of the Arp galaxies I've been featuring have been involved in a
collision. That isn't why Arp 13, also known as NGC 7448, made the
list. It is listed for having a detached segment(s). I can't tell if
Arp meant one or more detached parts for this particular galaxy. One is
obvious, the bright blob just west (right) of the center line at the
north end (top). But several detached pieces of arms and fainter blobs
are seen. In fact, while at first it appears to be a spiral it is badly
torn up into small pieces of spiral arms. It is part of a group known
as the NGC 7448 group. So where is this group? It sure isn't in my
photo. If NGC 7448 is the result of an interaction with one or more
galaxies in the group they have fled the scene of the mugging. Actually
they are over a half degree east of NGC 7448 thus well out of my field
of view. I can't fit both the group and NGC 7448 in one image. Some of
them show obvious signs of interaction. That isn't obvious in the case
of 7448 itself however. It is a blue galaxy indicating star formation
was strong in the recent past. Also the brightest knot is said to be
very bright in H-alpha light, as bright as the core of the galaxy. I
didn't realize this at the time I took it. Something to check out next
year. I can't find a good distance estimate for this galaxy, but it is
likely around 85 million light years away.

Star color is horrid in this image for several reasons. The blue frame
was taken months after the rest. Temperature was 30C colder changing
image scale. Camera rotation changed as well. At the time I didn't
have Registar and tried to match manually. I should have gone back and
let Registar do it. That would fix the registration at the corners.
But the real problem was the ice. I had none for the red and green but
it was severe the night I took the blue. This screwed up color balance
of the stars. Trying to get them right turned the galaxy purple to
blue. I found no solution. This was the best I could do. Seeing was
poor to bad which didn't help either. FWHM of blue was 5.6", that of
the other frames 3.8" to 4.2". I do need to do this one again but there
are so many on my to-do list (about 500) I don't see that happening any
time soon.

14" LX200R @ f/10, R=4x10' RGB=2x10', 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".

Rick, very good detail in this smallish galaxy. Looking for comparison
pictures I found that I imaged this galaxy in 2000 and 2002, so it's time
for another try next year.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Many of the Arp galaxies I've been featuring have been involved in a
collision. That isn't why Arp 13, also known as NGC 7448, made the
list. It is listed for having a detached segment(s). I can't tell if
Arp meant one or more detached parts for this particular galaxy. One is
obvious, the bright blob just west (right) of the center line at the
north end (top). But several detached pieces of arms and fainter blobs
are seen. In fact, while at first it appears to be a spiral it is badly
torn up into small pieces of spiral arms. It is part of a group known
as the NGC 7448 group. So where is this group? It sure isn't in my
photo. If NGC 7448 is the result of an interaction with one or more
galaxies in the group they have fled the scene of the mugging. Actually
they are over a half degree east of NGC 7448 thus well out of my field
of view. I can't fit both the group and NGC 7448 in one image. Some of
them show obvious signs of interaction. That isn't obvious in the case
of 7448 itself however. It is a blue galaxy indicating star formation
was strong in the recent past. Also the brightest knot is said to be
very bright in H-alpha light, as bright as the core of the galaxy. I
didn't realize this at the time I took it. Something to check out next
year. I can't find a good distance estimate for this galaxy, but it is
likely around 85 million light years away.

Star color is horrid in this image for several reasons. The blue frame
was taken months after the rest. Temperature was 30C colder changing
image scale. Camera rotation changed as well. At the time I didn't
have Registar and tried to match manually. I should have gone back and
let Registar do it. That would fix the registration at the corners.
But the real problem was the ice. I had none for the red and green but
it was severe the night I took the blue. This screwed up color balance
of the stars. Trying to get them right turned the galaxy purple to
blue. I found no solution. This was the best I could do. Seeing was
poor to bad which didn't help either. FWHM of blue was 5.6", that of
the other frames 3.8" to 4.2". I do need to do this one again but there
are so many on my to-do list (about 500) I don't see that happening any
time soon.

14" LX200R @ f/10, R=4x10' RGB=2x10', 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".