View Full Version here: : m83 and?
07-05-2012, 01:47 PM
Last night i decided to try imaging a galaxy... whichever i was able to find in the very bright moonlit sky :lol:
I happened upon M83, and also noticed a whisp of something else.
Today i processed the images, and apart from being almost useless (skyglow was just so bad), i was able to get something out of it.
Now i am trying to identify it.
Heavily processed image is here: http://core-au.net/astro/m83/m83-2.jpg
Slightly less processed image: http://core-au.net/astro/m83.jpg
The arms that lift above and below on the right side of the image are natural, but the blue/orange glow is a byproduct of processing it so much.
I thought it might have been Centaurus A, but it looks nothing like it.
07-05-2012, 02:59 PM
what your looking at there is nothing but a light leak! or a reflection of something within your system.
07-05-2012, 03:03 PM
To me it looks like refracted moonlight from high atmospheric ice crystals - just like a rainbow.
I whitnessed the very rare 42degee halo around the Sun a couple of months ago. From the position of the Moon last night relative to M83, you may have fluked a chance viewing of the same refractive phenomenon that would really would only have been visible in a long exposure photo. "Sun Dogs" look similar in structure as the artefact you've got in your image.
May be annoying, but if it is what I suspect, you've really got one lucky chance photo!
07-05-2012, 03:08 PM
Light leak. Never would have occurred to me. Could be too. With a full Moon too, anything could happen with long exposure photography.
07-05-2012, 03:55 PM
And here i was thinking i had a two-for-one photo ;)
Guess ill just crop that out then. Might make processing a bit easier.
First time out in 2-3 months thanks to the weather and it just happens to be a full moon - and not just any moon at that!
07-05-2012, 04:03 PM
grab your telescope and inside your home put the focuser to a bright light, if you can see light though the front objective and out the back just be wary when your imaging aka, computer screens, LED lights from power sources etc etc etc will all be a little bit of a nasty cause!
With my imaging rig you will see in the photos of it that i have what i call "The Shower cap" I was getting really strange circular effects kind of like vingetting. but all it the issue came down to was light slipping past the rear mirror and getting in that way.
08-05-2012, 12:32 AM
You can see some dark out-of-focus dust specs in the circular light patch, and the curvy 'v' shape looks supiciously like a caustic curve caused by a point source of light off-axis (to the left of your optic axis) and well within the focal length of the primary.
If it's a newtonian OTA is there a chance the focuser was pointed towards the moon? Or is there something bright and shiny in the field of view of the focuser when it is racked all the way in? I saw a similar phenomenon once on a newt where the manufacturer had thoughtfully placed a shiny chrome wingnut on the back of the secondary.
Another thing to watch is light getting in the viewfinder of the camera, if you're using a DSLR.
08-05-2012, 12:46 PM
Yeah the dust should hopefully be removed now. Dust was on the sensor, somehow it got in there.
Speaking of the light - when i was imaging this the moon was close, but well out of range of the FOV. There are two things i can think of: Light from the house somehow got in (altitude was fairly high) or the moon. I will try putting something over the view finder of the camera as well.
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