The Canary's Eyes

Saturday, July 12 2008 @ 03:00 am EDT

Contributed by: bobmoody

This incredibly detailed image of the Trifid Nebula helped me learn about an observatory on a mountaintop on the island of Tenerife in the Canary Islands of Spain. All images in this story used by permission from Daniel Lopez.
On a recent Astronomy Picture of the Day submission, I saw an incredibly detailed image of the familiar Trifid Nebula, M-20, in Sagittarius. Details in the image were better than almost any other image I'd ever seen of this object, and I did what I frequently do....I started clicking on the links associated with this particular image. These are the words and phrases of text which we see in blue, each connected to certain types of information about the image. Some dealt with the facility which took the image, its astronomer, the imaging equipment, all sorts of varied information linked to the APOD of the day.

By clicking on these links, I learned about an observatory in a little-known corner of the world, where other images with similar fine detail are regularly produced by one of the resident astronomers, Daniel Lopez. I clicked on Mr. Lopez's name and promptly sent him an email to ask permission to use his images for this story. Within only a couple of hours, Daniel had replied to my query and had given me permission to use not only his pictures, but also other images from the Observatorio del Teide.
The IAC 80 telescope of the Observatorio del Teide. Its a 32" f / 11.3 Classical Cassegrain. Click here for a zoomable image of the IAC 80. Images used by permission.
I had discovered the Observatorio del Teide on the island of Tenerife in the Atlantic Ocean, located off the coast of northern Africa in the Spanish Canary Islands.

What incredible detail this image had. The dusty innards of the distinctive trisecting lanes show more fine resolution than most of us have ever seen. Surely, the telescope and camera that took this image must have been one of the world's larger instruments, using a mega-sized CCD camera, I thought, but I was SOOO, wrong!

I had until that time never heard of the IAC telescope (IAC being the Instituto de Astrofísica de Canarias). What amazed me was that this was a telescope of LESS than 1 meter in diameter! Its actually a .8m mirror, of a Cassegrain design with a focal ratio of 11.3. Translation, its a 32" f/11.3 Classical Cassegrain truss-tube OTA on a German Equatorial Mount. Simply amazing!

Click "Read More" for more technical details and more images

This image of M-20 looks different from many other images of this same object, due to certain particular filters which Daniel Lopez used on the IAC 80 telescope. We're usually used to seeing images made with RGB filters (Red; Green; Blue), but in the last few years we are seeing more and more images taken with so-called "narrow-band" filters sensitive to wavelengths associated with atoms of Hydrogen, Oxygen and Sulfur (HOS). It is partly the use of these specialized filters that allow transmission of specific wavelengths of light which creates more detail to be seen from the "stuff" which comprises this, as well as many other emission nebulae, too. When HOS and RGB images are used together, astronomers have another tool for understanding the object's chemical constituents in completely new ways. Here is a link to an image of the Crab Nebula, M-1, taken with the RGB and the narrow-band filters on the IAC 80, illustrating how BOTH sets of filters can work in tandem to create an almost 3D effect. This is a GREAT image of M-1!

Another image from the IAC 80 telescope seen on APOD, this time of the Pillars of Creation in M-16, the "Eagle Nebula" in Sagittarius.

These specialized filters are now available to those of us who are just amateur astronomers. For all those who now take pictures of celestial objects even remotely resembling the images I have used for this story, its an exciting time to be an astroimager. If for no other reason than to produce beautiful "companion" images to the normal RGB filtered shots, obtaining a set of these HOS-type filters are well worth the cost involved, which is about that of most specialty filters, around the $100 to $300 per-filter range.

I could almost predict that astro-imagers from our own immediate area will soon be taking HOS filtered images of their own. Using HOS filters will almost certainly soon be common place, so I guess I'll have to buy another storage device for these new images when they begin to become prevalent on web sites, around the world, and in APOD archives as well as on so many other locations. But you know, that's fine with me!

I would like to thank Daniel Lopez for allowing me permission to use his images and the images of the IAC telescope of the Observatorio del Teide. I'm quite sure we'll all have more images from this facility and from this astronomer in the future. I 'll be looking forward to that, eagerly.

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