Another Astrophoto!

[h2olawyer]

Well, I managed to take a trip out to some really dark skies Thursday night.  From my house, I have absolutely no view to the south below the ecliptic (the path the planets generally follow in the sky).  In the Summer, there are all kinds of great things to look at and image in that area.  The center of the Milky Way galaxy is in the area of the constellation Sagittarius.  As you can see in this photo, there are a whole bunch of stars out that way.

For those interested, this photo is a stack of 8 exposures of 4 minutes each.  I shot 15 exposures, but the guiding wasn't that great and only about half were usable.  I used my Canon Rebel 450D, through the 8 inch Newtonian telescope.  ISO setting was 1600.  The spikes on each star are caused by the light of those stars being diffracted by the 4 vanes that support the secondary mirror (which directs the image out through the side of the telescope and on into the eyepiece or onto the imaging chip of the camera.

I had planned to take at least 30 exposures, but took a while to figure out what was causing a 4 minute delay between exposures.  I discovered a new setting in the image capture software and reset it to a 5 second delay between shots.  That really sped things up!  Next time out, I want to get 2 to 3 hours of total exposure time.  This one isn't bad for only 32 minutes total time - but it took over 2 hours to get the 15 exposures.  Next outing, I'll be able to make better use of the time.   ::)  This is a really steep learning curve!

It is heavily processed after stacking, using Nebulosity and GIMP.  I boosted the red slightly.  The results were compressed into a jpeg and reduced in size.  This is actually a very red object, but the infrared filter that comes from the factory in all DSLRs cuts out a fair amount of red light as well.  Infrared would focus at a much different point than the visible spectrum & allowing it to pass in all cameras would cause all the photos to be blurry.  I will be sending the camera out to have the filter replaced with one that is more sensitive to those red wavelengths.

H₂O

EDIT: For some cool astro-photos changed daily: http://antwrp.gsfc.nasa.gov/apod/

[akvision]

Very nice!  In mid winter our sky is night brilliant.  I am not much of a photo taker though.

[h2olawyer]

Thanks!  I'd love to get up your direction sometime for the Northern Lights.  They are seen once in a while this far south, but are just a green or orange glow on the northern horizon.

I'm just getting started in this astrophoto stuff.  Started working on it in March.  It can be a real money hog, but I'm (mostly successfully)trying to keep the costs as low as possible.  It is definitely a time consuming endeavor.  It took my camera, computer plus a minor user error, well over 2 hours to get the 15 four minute exposures I took for this photo.  Of those 15, only 8 were good enough to use.  Those are then stacked and processed.  Another time waster is taking dark exposures to eliminate noise & bad pixels.  You take a minimum of 5 darks and each of those are the same exposure settings as the main images.  They need to be taken within 5 degrees F of the ambient temp the main images were taken.  I'm slowly building a library of master darks so that will become a non-issue in the future.  The entire process gets pretty complex and I'm still just shooting the image frames & dark frames.  I'm about to start taking flat frames & bias frames, then adding those into the mix.

I'm going to a star party in the panhandle of Oklahoma in September.  Supposed to be a full week of really dark skies (weather permitting).  Hope to get 2 or 3 nights of imaging and 2 or 3 mights of observing some of the eye candy.

The image above was taken at an elevation of 9500 feet, on Rabbit Ears Pass, near Steamboat Springs, CO.  A good friend's brother works for the state highway department and lives up there.  We had access to power, a kitchen to make coffee, a place to warm up & most importantly, a place to escape the very hungry mosquitoes that were even daring to penetrate the Deep Woods Off!  There is some skyglow from Steamboat, but it is minimal and there's no light dome that direction - or in any other direction for that matter.  The Milky Way was visible from horizon to horizon and several of the brighter Messier objects were easily visible to the naked eye.

H₂O

[funkamongus]

very nice.

[Re-Vision]

Truly awesome, I kind of lost interest in astronomy when I returned to Texas because of so much light pollution around the Houston and then the Ft. Worth area.  I moved two years ago and discovered my old six inch mirror had gave up the ghost when the aluminum began to peel off.  What type and size of scope are you using?  Went from No. Dakota to Alaska and the Northern lights changed from a glow in the sky to the truly amazing displays you see in the National Geographic magazines except they are constantly moving and changing colors.  About ten years ago I was out jogging and noticed an orange glow in the South East, absolutely could not imagine what it was, next day the newspaper said it was Northern light phenomena. SE sky?, go figure.  BDC

[h2olawyer]

Thanks for the compliment.  Astronomy can be done even under pretty heavy light pollution.  My cousin took images off many Arp galaxies under the skyglow of Houston.

I have an 8 inch Newtonian telescope on a computerized german equatorial mount.  It is a Celestron C8N-GT in their catalog.  I was looking for a telescope that would work well for both visual and photographic uses.  It isn't a real great planetary tool, but it is fantastic on the fainter, fuzzier stuff that kindles most of my interest.  It also works great for Lunar observation.

The computerized go-to system is wonderful.  I get the scope aligned, then just enter the name or number of what I want to look at and the mount automatically points the scope at the target.  It is normally near the center of my 17mm Televue Plossl eyepiece.

To take longer exposures, I have added a guide camera - a small camera attached to a 50mm finderscope body.  It runs through the laptop, and keeps everything pointed at a selected star, sending correction commands to the mount when it detects the star moving more than o.15 pixels.  Amazing stuff.  It is sold by KW Telescopes in Kitchener, Ontario - near some of our fellow ROVers.  My imaging camera is a Canon Rebel XSi or 450D - depending on where on Earth it was sold.  12.1MP and full camera control through a USB cable.

I could go on for a long time detailing all the stuff required to get to the point I'm at.  Most serious astrophotographers say you can't take good photos without spending at least $20,000.  I'm just barely over 10% of that cost and feel things are coming along fairly well.  I'd like a couple different optical tubes so I can have more variety in the things I image, and will eventually get a better mount / tripod, but still will be nowhere near that $20,000 figure.  The modern DSLR cameras and inexpensive guiders have done wonders in making it a more affordable pursuit.

H₂O