ToddSpace: John's Astrophotography Page

The Lagoon and Trifid Nebulas

Here in New England, us astrophotographers are faced with a considerable challenge when pursuing some of the most stunning deep sky objects our galaxy (the milky way) has to offer.  While the constellation cygnus rides directly up above on summer evenings and is filled with billowing clouds of nebulous gas, some of the most stunning astrophotography targets unfortunately lie much closer to Sagittarius which never rises much more than about 25 degrees over the southern horizon.  This means that in order to capture these colorful gems, one must pack up and head for a dark field in the middle of nowhere.  On the night of Friday August 25th I did just that, heading out to Chesterville Maine with about 200lbs of astro-gear for a remote imaging session.  Problem with these sessions is to do advanced astrophotography, you have to have about 100 things in just the right place and everything must go right, which fortunately, it did that night.  The following night my shutter cable failed so I went the same way as the sox in September, downhill. 

Fortunately, on the night of the 25th I was able to shoot the Lagoon and trifid nebulas, a colorful celestial pair that ride just above the spout of sagittarius' teapot.  On a clear dark night, you can easily see the lagoon nebula as a ill defined patch of greyish light.  The trifid nebula, being much smaller, is much more difficult to see.  This particular photograph is a composite of 6 5 minute exposures with my Tak E-160 (f3.3) and my canon 350d.  Nice thing about havnig a laptop in the field that evening with me is I could sit in my car while the laptop automated everything for me, this was particularly useful as a friendly skunk paid me a visit around 1:00am. 

The Trifid nebula was so named because a dark dust lane trisects it into three distinct nebulas, although later visual observations tagged it a "four lobbed nebula".  Here is a closeup of the trifid nebula.  Surrounding the trifid nebula you'll see a bright blue reflection nebula... it's referred to as a reflection nebula because it doesn't emit its own light, rather, it's just the reflection of nearby bright blue starlight off of interstellar dust clouds. 

A closeup of the Lagoon nebula reveals one of the most fascinating elements of the dynamics of our milkyway, and it also eludes to the vastness of it.  In the closeup below, you can see dark lanes that look to be about the size of a tadpole swimming through this vast nebulous ocean:

Click on the thumbnail to view.  These tiny dark lanes are collapsed clouds of protostellar dust and are not tiny, they measure about 10,000 AUs in width... how big is that?  An AU is an astronomical unit which is 93,000,000 miles, the distance from the earth to the sun.  In other words, incomprehensibly large... and just barely discernable from earth based telescopes.  Kind of gives you an appreciation for the vastness of space! 

I've had a few requests for some of these photos to be used as desktop wallpaper, if you're interested feel free to email me. 

Next up... the Veil nebula, an expanding supernova remnant.

The North American and Pelican Nebulas in Color

In the last week I've had two wonderful clear dark skies to get out and photograph this gem that crosses the zenith around 10:00pm this time of year (August).  As previously photographed, these aer the pelican and north american nebulas shot through my Takahashi E-160 telescope and my modified canon 350d.  The first shot is a hydrogen alpha only photograph:

Click on this thumbnail to see the full resolution photograph.  The deep thick knots of nebulosity here show up as almost white.  Using a deep red hydrogen alpha filter I am able to reject all sources of light pollution and isolate just the nebula itself, this results in a very very rich nebula field in a fairly short exposure.  This is a grand total of 15 minutes exposure time.  Both of these nebulas are visible to the naked eye in VERY dark skies just to the southeast of the bright summer star Deneb. 

Next up is the same photograph only shot in color.  Whenever I post a color photo like this the immediate response is "cool!  will I see that in my telescope?", the answer sadly is no way in hades!  Reason is is that this is a very dim nebula with all of its surface brightness spread out over a very large area.  Because of this, your eye will tend to see grey, this is the natural tendency of our eyes when faced with discerning the shape or color of a very dim object.  However, long exposure photography solves this dilemna for us as the camera serves to collect light over a long period of time giving us all the glorious detail seen in this photos.  This is a 42 minute total exposure time.  Six individual 7 minute photos were combined in photoshop to generate this image.  I've been asked before how come I don't just take a 42 minute exposure and why go through the process of compositing so many sub exposures?  Answer is simple, these images all build up noise on the sensor (all electronic light sensors build up noise, unwanted grain shows up on the image), by layering them you increase the signal to noise ratio, in other words, the more photos, the more nebula, and the noise is random, so it ends up cancelling out all the noise of the other images, so you end up with a nice smooth background.  There are some wonderful tutorials on this on the web.  Next up is the trifid and lagoon nebulas, a colorful section of the sky with both red hydrogen alpha emission and blue reflection nebulas intersected with dark dust lanes.

Photographing Meteors

If you’ve spent some time looking at the night time sky you’ve undoubtedly seen “shooting stars” on occasions.  These are typically tiny pieces of space junk about the size of a grain of sand entering and burning up in the earth’s atmosphere (contrary to their popular moniker, they are not stars).  On a few annual occasions, the Earth will pass through a trail of debris left over from a passerby, typically a comet, making the meteor’s more frequent and somewhat predictable.  Today, August 14^th, we are passing through one of those space debris trails leftover from the passing of comet Swift-Tuttle.  The meteors in a meteor shower typically come from a particular point in the sky called a “radiant” and the tails of all incoming meteors will point back to the radiant.  The perseid meteor shower is so named because the radiant is in the autumn constellation Perseus.  The Perseids are a very long lasting shower that start about two weeks prior to Aug 12^th and last about two weeks after, although the greatest activity is around Aug 11-14^th (typically). 

This past weekend I was up in

Maine

and I managed to photograph a single Perseid meteor (I saw maybe 10 meteors in two nights of watching, very slow shower).  So how does one photograph a meteor?  Pure dumb luck helps a ton.  Here’s how I do it.  Before it gets dark, make sure you focus your camera lens at infinity and leave it there.  I like to use a lens in the 17-50mm range, the wider the field of view, the easier it is to catch one.  A narrower field of view (like with a 50mm lens) will get you a much smaller patch of sky, but if you happen to catch a meteor, it should be a brilliant photograph.  Faint meteors will not show up on a wide angle photo, while they will show up with a narrower field of view.  So I set my Canon 20d to ISO 1600, 30 second exposures, lens at 18mm f/4 (open the lens f-stop wide open), put it on a tripod and pointed it up.  I hooked the camera up to a shutter release cable so after each 30 second exposure, it took another exposure.  I took 200 shots in all.  Unfortunately, my focus did slip some (still not sure how that happened) so my one meteor is somewhat fuzzy, definitely not good enough for an 8x10 on the wall.  Please note, 30 second exposures are enough to show some trailing of stars, but not much, as you can see in the attached photo.

The next major predictable meteor shower will be on Nov 19^th as the Leonids put on their annual show.