ASTRO: Geostationary satellites and Arp 146

Astro image tip. Avoid objects in the geostationary satellite belt! No
one told me this so I had a night of better than average seeing and
decided to try for Arp 146 which is too far south for me to image on an
average night being about 6.5 degrees south. That put it at the
northern edge of the geostationary satellite belt as seen from my
latitude. Such communications satellites aren't really stationary in
the sky. They make a small, about 1 degree high figure 8 pattern around
their geostationary assigned position. From my location Arp 146 is
right at the northern edge of that pattern. So I ended up imaging lots
of communications satellites, some long dead rather than my object. I
removed them from the color frames as well as all but one luminosity
frame. One frame only had 3 and I decided to leave them in to give a
flavor of what I had to deal with. There were 29 satellite trails in
total with 5 in one blue frame. Notice the angled trails. They may be
due to decommissioned geostationary satellites. When they are about to
run out of station keeping fuel -- the orbit is unstable and the figure
8 pattern grows with time so fuel is needed to keep the bird within its
prescribed spot so fixed dishes still see it -- it is moved several
hundred miles higher to get it out of the way. The last of the fuel is
used for this. With time the orbit is altered by the non spherical
earth and pull of the moon and sun until it is somewhat inclined to the
equator. That is why I believe them to be deactivated satellites.
Nearly all I removed from the image were horizontal as you'd expect for
an active geostationary satellite not moved to the graveyard. Also one
is using spin stabilization. That's no longer used as far as I can
determine. This causes it to blink as its reflectivity changes with its
spin. It doesn't move across the entire image as I terminated the
exposure before it had moved all the way across the image. You will see
places where the trails fade. This is due to small clouds passing by.
They didn't totally block the light but did dim it some for a few
seconds. The entire image was dimmed but that isn't seen except by
moving objects. At my image scale these appear to move at about 14.75
pixels per second which is my tracking rate at this declination.

Notice the bright trail just below Arp 146. It is an active
geostationary satellite though its trail wavers like the satellite is
drunk. The others do as well. This is due to our atmosphere. This is
the seeing I am constantly complaining about. It rapidly moves the star
around in the sky. It does the same for the satellite. This one had
just the right exposure to show this motion very clearly. The worse the
seeing the more "drunk" the trail. The effect of this is to blur the
image and is why major observatories are located on mountain tops where
they look through far less air than I have to look through. Also they
pick mountains that have what is called laminar air flow. This is a
very smooth flow of air that further reduces seeing problems. No
mountains and rarely any laminar air flow at my location so stars are
fuzzy. I can't do much about it. The third satellite is also a
decommissioned one as told by its angled trail.

Now for Arp 146. It is classed by Arp under "Galaxies (not classifiable
as S(pherical) or E(liptical)): With associated rings. There are three
in this class. Arp 147 and 148 I've run previously. 147 was the 10
galaxy Hubble made famous and 148 is Mayall's Object, the bullet through
a galaxy that is also a famous Hubble image. Hubble hasn't as yet
released a pretty image of this one. I didn't check the archive to see
if it has taken it or not. If so only the raw data is available and
that's not suitable for the internet without many hours of processing.
So I finally beat Hubble to one.

Arp 146 is composed of two galaxies PGC 509 S pec (Ring B) and PGC 510
S0 pec (Ring A). PGC 509 is the ring while 510 the bullet that made the
ring. Why the bullet is usually referred to as Ring A I've not figured
out. It is rarely a ring though this one seems to have just one arm
that looks much like a ring. The galaxies are just under a billion
light years away thus rather small in angular size. While 510 is
classed as S0, it does seem to have a single spiral arm. S0 galaxies
aren't supposed to have defined arms but be just a spindle of stars.
That isn't the case here.

I could find no red shift data for any other galaxy in the image. Not
even one MASX IR galaxy is in the image. Only those whose positions
were automatically measured by a APMUKS. It gathers little data other
than position and some photometric data. So this is a part of the sky
not well studied.

The asteroid to the lower right of Arp 146 is (38878) 2000 SL121 at
magnitude 17.8

It is located in Cetus the whale right up against the border with Pisces
and Aquarius. Right in the geostationary belt for my latitude. Grrr.

Arp's photo of this is at:
http://nedwww.ipac.caltech.edu/level...ig_arp146.jpeg

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

I've attached two images, the full frame at my normal 1" per pixel and a
cropped enlargement of Arp 146 at 0.75" per pixel to better show this
small pair.

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".

Great picture and I enjoyed reading the description. The ring galaxy looks
like it is completely hollow.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Astro image tip. Avoid objects in the geostationary satellite belt! No
one told me this so I had a night of better than average seeing and
decided to try for Arp 146 which is too far south for me to image on an
average night being about 6.5 degrees south. That put it at the
northern edge of the geostationary satellite belt as seen from my
latitude. Such communications satellites aren't really stationary in
the sky. They make a small, about 1 degree high figure 8 pattern around
their geostationary assigned position. From my location Arp 146 is
right at the northern edge of that pattern. So I ended up imaging lots
of communications satellites, some long dead rather than my object. I
removed them from the color frames as well as all but one luminosity
frame. One frame only had 3 and I decided to leave them in to give a
flavor of what I had to deal with. There were 29 satellite trails in
total with 5 in one blue frame. Notice the angled trails. They may be
due to decommissioned geostationary satellites. When they are about to
run out of station keeping fuel -- the orbit is unstable and the figure
8 pattern grows with time so fuel is needed to keep the bird within its
prescribed spot so fixed dishes still see it -- it is moved several
hundred miles higher to get it out of the way. The last of the fuel is
used for this. With time the orbit is altered by the non spherical
earth and pull of the moon and sun until it is somewhat inclined to the
equator. That is why I believe them to be deactivated satellites.
Nearly all I removed from the image were horizontal as you'd expect for
an active geostationary satellite not moved to the graveyard. Also one
is using spin stabilization. That's no longer used as far as I can
determine. This causes it to blink as its reflectivity changes with its
spin. It doesn't move across the entire image as I terminated the
exposure before it had moved all the way across the image. You will see
places where the trails fade. This is due to small clouds passing by.
They didn't totally block the light but did dim it some for a few
seconds. The entire image was dimmed but that isn't seen except by
moving objects. At my image scale these appear to move at about 14.75
pixels per second which is my tracking rate at this declination.

Notice the bright trail just below Arp 146. It is an active
geostationary satellite though its trail wavers like the satellite is
drunk. The others do as well. This is due to our atmosphere. This is
the seeing I am constantly complaining about. It rapidly moves the star
around in the sky. It does the same for the satellite. This one had
just the right exposure to show this motion very clearly. The worse the
seeing the more "drunk" the trail. The effect of this is to blur the
image and is why major observatories are located on mountain tops where
they look through far less air than I have to look through. Also they
pick mountains that have what is called laminar air flow. This is a
very smooth flow of air that further reduces seeing problems. No
mountains and rarely any laminar air flow at my location so stars are
fuzzy. I can't do much about it. The third satellite is also a
decommissioned one as told by its angled trail.

Now for Arp 146. It is classed by Arp under "Galaxies (not classifiable
as S(pherical) or E(liptical)): With associated rings. There are three
in this class. Arp 147 and 148 I've run previously. 147 was the 10
galaxy Hubble made famous and 148 is Mayall's Object, the bullet through
a galaxy that is also a famous Hubble image. Hubble hasn't as yet
released a pretty image of this one. I didn't check the archive to see
if it has taken it or not. If so only the raw data is available and
that's not suitable for the internet without many hours of processing.
So I finally beat Hubble to one.

Arp 146 is composed of two galaxies PGC 509 S pec (Ring B) and PGC 510
S0 pec (Ring A). PGC 509 is the ring while 510 the bullet that made the
ring. Why the bullet is usually referred to as Ring A I've not figured
out. It is rarely a ring though this one seems to have just one arm
that looks much like a ring. The galaxies are just under a billion
light years away thus rather small in angular size. While 510 is
classed as S0, it does seem to have a single spiral arm. S0 galaxies
aren't supposed to have defined arms but be just a spindle of stars.
That isn't the case here.

I could find no red shift data for any other galaxy in the image. Not
even one MASX IR galaxy is in the image. Only those whose positions
were automatically measured by a APMUKS. It gathers little data other
than position and some photometric data. So this is a part of the sky
not well studied.

The asteroid to the lower right of Arp 146 is (38878) 2000 SL121 at
magnitude 17.8

It is located in Cetus the whale right up against the border with Pisces
and Aquarius. Right in the geostationary belt for my latitude. Grrr.

Arp's photo of this is at:
http://nedwww.ipac.caltech.edu/level...ig_arp146.jpeg

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

I've attached two images, the full frame at my normal 1" per pixel and a
cropped enlargement of Arp 146 at 0.75" per pixel to better show this
small pair.

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".