A Space & astronomy forum. SpaceBanter.com

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » SpaceBanter.com forum » Others » Astro Pictures
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

NGC 4236 Another low surface brightness M81 group galaxy 2nd try



 
 
Thread Tools Display Modes
  #1  
Old March 17th 08, 12:19 AM posted to alt.binaries.pictures.astro
Rick Johnson[_3_]
external usenet poster
 
Posts: 262
Default NGC 4236 Another low surface brightness M81 group galaxy 2nd try

Here it is with more saturation.
Rick

Rick Johnson wrote:

It seems the only clear nights I get are also moon lit. I'm not all
that great at processing moon lit images. Still it sort of works.

This galaxy was much bigger than I expected. It is listed as about 6
minutes shorter than M81 which fit nicely on my frame but this guy is
actually larger but tilted about the same. Looking at the short 5"
image I used for checking if the mount hit it I saw a star that was dead
center on my chip and seemed dead center along the bright bar of the
galaxy. Not until I processed it and could see the fainter parts did I
realize the southern part extends farther. The star was indeed about
the center of the bar but this galaxy is quite unsymmetrical. Not sure
if I missed anything below the southern end or not.

This is one blue galaxy. At first I thought it due to moonlight but
checking the few other color images it seems right. How a galaxy has
mostly brilliant blue stars can be so faint I'm not sure. Some reports
call it heavily obscured but I'd expect that to redden it some. I see
no sign of that.

I am impressed by the number of faint galaxies in this image. Looks to
me that there may be more of them than foreground stars. Unfortunately,
seeing wasn't all that good so its hard to tell.

This was taken over two nights. I took my usual 4x10' and 2x10 minute
series but it was so low luminosity I waited for another clear night to
do it again. First night had a 3 day old moon that set before I took
color data. I used those frames to check that my color was correct.
Then the last frame was taken at 5 days when the moon was in the sky
giving me fits on all frames. Still, I got a better result using all
frames. Seeing was better the moon lit night as well which helped a bit
as well as fogging the faint stuff.

In all this is one surprisingly big galaxy. It is listed at 11.5
million light years (M81 is 12). Brightest blue stars are listed at
19th magnitude and as this shot easily goes well below that some of
those "stars" in the galaxy really are stars and not clusters it would
seem. Which is which is the question.

H-alpha might show up some HII regions but I sure don't see any in the
RGB data. They must be smaller than my seeing allowed me to resolve.

Earlier this galaxy was so high a declination it was in my Polaris tree
all the time. Last year I had no trouble reaching 70 degrees but
couldn't this winter. 67 was about the limit unless I wanted to image
many nights using a 25 minute window, then I could hit 68. But now I'm
back to 70. Snow is out of the tree after high winds blew it all far to
the north of me. That means the tree leans toward me when snow covered.
I waded through the snow (still 18" on the ground) to get a good look
at it with a plumb bob. It is leaning about 5 degrees toward the
observatory even now, and has been apparently, but with a heavy snow
load it leans even more. Not sure if that means I could have a bisected
observatory or not. I think I'll have a tree guy I know give his
assessment. It saves me a lot of time raking snow off the roof. Nothing
like standing atop a 10' ladder atop a 9' deck using a 26' snow rake
trying to remove snow off the observatory. It's a long way down from up
there! Thanks to the tree I didn't need to do it at all last year
(light snow) and only once this year (normal snow). But the snow on the
house roof that isn't protected indicates I'd have been doing it about 8
times this winter without the tree. When the snow load is heavy rolling
the roof would dump it all into the observatory as it rolled back. That
I don't need. I only clean off the south side as the north side dumps
only outside the observatory and isn't a problem. So I'm now in a
quandary over the tree. Unlike my Meridian Tree, this one is legal to
cut, though at 100 feet expensive to do as it has to be tied off and cut
in short sections to be sure it doesn't fall on the observatory.

14" LX200R @ f/10, L=8x10' binned 2x2, RGB=4x10' binned 3x3,
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".

Attached Thumbnails
Click image for larger version

Name:	NGC4236LUM8X10RGB4X10X3R2.jpg
Views:	335
Size:	266.5 KB
ID:	1778  
Ads
  #2  
Old March 17th 08, 01:50 PM posted to alt.binaries.pictures.astro
Richard Crisp[_1_]
external usenet poster
 
Posts: 985
Default NGC 4236 Another low surface brightness M81 group galaxy 2nd try

looks good to me Rick

you sure have a lot of background galaxies in that shot too.


"Rick Johnson" wrote in message
...
Here it is with more saturation.
Rick

Rick Johnson wrote:

It seems the only clear nights I get are also moon lit. I'm not all
that great at processing moon lit images. Still it sort of works.

This galaxy was much bigger than I expected. It is listed as about 6
minutes shorter than M81 which fit nicely on my frame but this guy is
actually larger but tilted about the same. Looking at the short 5"
image I used for checking if the mount hit it I saw a star that was dead
center on my chip and seemed dead center along the bright bar of the
galaxy. Not until I processed it and could see the fainter parts did I
realize the southern part extends farther. The star was indeed about
the center of the bar but this galaxy is quite unsymmetrical. Not sure
if I missed anything below the southern end or not.

This is one blue galaxy. At first I thought it due to moonlight but
checking the few other color images it seems right. How a galaxy has
mostly brilliant blue stars can be so faint I'm not sure. Some reports
call it heavily obscured but I'd expect that to redden it some. I see
no sign of that.

I am impressed by the number of faint galaxies in this image. Looks to
me that there may be more of them than foreground stars. Unfortunately,
seeing wasn't all that good so its hard to tell.

This was taken over two nights. I took my usual 4x10' and 2x10 minute
series but it was so low luminosity I waited for another clear night to
do it again. First night had a 3 day old moon that set before I took
color data. I used those frames to check that my color was correct.
Then the last frame was taken at 5 days when the moon was in the sky
giving me fits on all frames. Still, I got a better result using all
frames. Seeing was better the moon lit night as well which helped a bit
as well as fogging the faint stuff.

In all this is one surprisingly big galaxy. It is listed at 11.5
million light years (M81 is 12). Brightest blue stars are listed at
19th magnitude and as this shot easily goes well below that some of
those "stars" in the galaxy really are stars and not clusters it would
seem. Which is which is the question.

H-alpha might show up some HII regions but I sure don't see any in the
RGB data. They must be smaller than my seeing allowed me to resolve.

Earlier this galaxy was so high a declination it was in my Polaris tree
all the time. Last year I had no trouble reaching 70 degrees but
couldn't this winter. 67 was about the limit unless I wanted to image
many nights using a 25 minute window, then I could hit 68. But now I'm
back to 70. Snow is out of the tree after high winds blew it all far to
the north of me. That means the tree leans toward me when snow covered.
I waded through the snow (still 18" on the ground) to get a good look
at it with a plumb bob. It is leaning about 5 degrees toward the
observatory even now, and has been apparently, but with a heavy snow
load it leans even more. Not sure if that means I could have a bisected
observatory or not. I think I'll have a tree guy I know give his
assessment. It saves me a lot of time raking snow off the roof. Nothing
like standing atop a 10' ladder atop a 9' deck using a 26' snow rake
trying to remove snow off the observatory. It's a long way down from up
there! Thanks to the tree I didn't need to do it at all last year
(light snow) and only once this year (normal snow). But the snow on the
house roof that isn't protected indicates I'd have been doing it about 8
times this winter without the tree. When the snow load is heavy rolling
the roof would dump it all into the observatory as it rolled back. That
I don't need. I only clean off the south side as the north side dumps
only outside the observatory and isn't a problem. So I'm now in a
quandary over the tree. Unlike my Meridian Tree, this one is legal to
cut, though at 100 feet expensive to do as it has to be tied off and cut
in short sections to be sure it doesn't fall on the observatory.

14" LX200R @ f/10, L=8x10' binned 2x2, RGB=4x10' binned 3x3,
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".



  #3  
Old March 22nd 08, 06:56 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default NGC 4236 Another low surface brightness M81 group galaxy 2nd try

Mighty image Rick. I never imaged this galaxy because I wanted to save it
for a very good night and never got around to imaging it.

Stefan

"Richard Crisp" schrieb im Newsbeitrag
et...
looks good to me Rick

you sure have a lot of background galaxies in that shot too.


"Rick Johnson" wrote in message
...
Here it is with more saturation.
Rick

Rick Johnson wrote:

It seems the only clear nights I get are also moon lit. I'm not all
that great at processing moon lit images. Still it sort of works.

This galaxy was much bigger than I expected. It is listed as about 6
minutes shorter than M81 which fit nicely on my frame but this guy is
actually larger but tilted about the same. Looking at the short 5"
image I used for checking if the mount hit it I saw a star that was dead
center on my chip and seemed dead center along the bright bar of the
galaxy. Not until I processed it and could see the fainter parts did I
realize the southern part extends farther. The star was indeed about
the center of the bar but this galaxy is quite unsymmetrical. Not sure
if I missed anything below the southern end or not.

This is one blue galaxy. At first I thought it due to moonlight but
checking the few other color images it seems right. How a galaxy has
mostly brilliant blue stars can be so faint I'm not sure. Some reports
call it heavily obscured but I'd expect that to redden it some. I see
no sign of that.

I am impressed by the number of faint galaxies in this image. Looks to
me that there may be more of them than foreground stars. Unfortunately,
seeing wasn't all that good so its hard to tell.

This was taken over two nights. I took my usual 4x10' and 2x10 minute
series but it was so low luminosity I waited for another clear night to
do it again. First night had a 3 day old moon that set before I took
color data. I used those frames to check that my color was correct.
Then the last frame was taken at 5 days when the moon was in the sky
giving me fits on all frames. Still, I got a better result using all
frames. Seeing was better the moon lit night as well which helped a bit
as well as fogging the faint stuff.

In all this is one surprisingly big galaxy. It is listed at 11.5
million light years (M81 is 12). Brightest blue stars are listed at
19th magnitude and as this shot easily goes well below that some of
those "stars" in the galaxy really are stars and not clusters it would
seem. Which is which is the question.

H-alpha might show up some HII regions but I sure don't see any in the
RGB data. They must be smaller than my seeing allowed me to resolve.

Earlier this galaxy was so high a declination it was in my Polaris tree
all the time. Last year I had no trouble reaching 70 degrees but
couldn't this winter. 67 was about the limit unless I wanted to image
many nights using a 25 minute window, then I could hit 68. But now I'm
back to 70. Snow is out of the tree after high winds blew it all far to
the north of me. That means the tree leans toward me when snow covered.
I waded through the snow (still 18" on the ground) to get a good look
at it with a plumb bob. It is leaning about 5 degrees toward the
observatory even now, and has been apparently, but with a heavy snow
load it leans even more. Not sure if that means I could have a bisected
observatory or not. I think I'll have a tree guy I know give his
assessment. It saves me a lot of time raking snow off the roof. Nothing
like standing atop a 10' ladder atop a 9' deck using a 26' snow rake
trying to remove snow off the observatory. It's a long way down from up
there! Thanks to the tree I didn't need to do it at all last year
(light snow) and only once this year (normal snow). But the snow on the
house roof that isn't protected indicates I'd have been doing it about 8
times this winter without the tree. When the snow load is heavy rolling
the roof would dump it all into the observatory as it rolled back. That
I don't need. I only clean off the south side as the north side dumps
only outside the observatory and isn't a problem. So I'm now in a
quandary over the tree. Unlike my Meridian Tree, this one is legal to
cut, though at 100 feet expensive to do as it has to be tied off and cut
in short sections to be sure it doesn't fall on the observatory.

14" LX200R @ f/10, L=8x10' binned 2x2, RGB=4x10' binned 3x3,
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".





 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
NGC 4236 Another low surface brightness M81 group galaxy Rick Johnson[_3_] Astro Pictures 6 March 18th 08 06:19 PM
Surface Brightness of Deep-Sky Objects Measured with a Digital Camera Sam Wormley Amateur Astronomy 0 June 27th 06 06:44 AM
Question about galaxy brightness [email protected] Astronomy Misc 1 November 5th 05 02:18 AM
surface brightness and photons [email protected] Amateur Astronomy 22 April 15th 05 01:42 AM
Surface brightness of Mars M. Tettnanger Amateur Astronomy 4 September 3rd 03 08:42 PM


All times are GMT +1. The time now is 01:34 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright 2004-2019 SpaceBanter.com.
The comments are property of their posters.