| Date: | 2010-06-16 07:35 |
|---|---|
| Author: | Stefano |
| category: | Astronomy, Photography |
| tags: | Bopp, comet, Hale, McNaught |
| slug: | mcnaught-comet-in-the-sky-and-pics-of-hale-bopp |
| attachments: | blog/wp-content/uploads/2010/06/halebopp-compare.jpg, blog/wp-content/uploads/2010/06/halebopp-1-web.jpg, blog/wp-content/uploads/2010/06/halebopp-2-web.jpg |
The McNaught comet, or C/2009 R1, is likely to be visible in the night sky starting tonight, for a week. You should be able to spot it near the constellation of Perseus as a fuzzy streak of light.
The comet should be visible with a small binocular, or just with the naked eye. In particular, I recommend using the so-called averted vision: don't look directly at the comet, but do it laterally, with your peripheral vision. This same technique can be used to watch any faint objects, such as galaxies and nebulae. You will also need a clear sky and low light pollution: leave the city and get in the countryside. I suggest also adapting your eyes to darkness for 10-15 minutes by not looking at anything bright, eventually bringing with you a flashlight with a dark red filter (which ruins your darkness vision much less than white light). If you have a telescope, prefer 25 or even 40 mm eyepieces, which give better contrast and a large field of view.
To find the constellation of Perseus, you have to know how to stargaze and orient yourself in the night sky. It should be in the Northeast, well into the night (2-3 am or even later). In the northern hemisphere, to approximately find the North look at the direction of sunset (West); at your right is the North, behind you is the East, and at your left is the South. Perseus can be found in a streak of sky between the big dipper (four almost rectangular bright stars and a curved handle made of three stars) and Cassiopeia, which has an unmistakable W shape. Both these constellations can be found in the North direction. Move your eyes towards East along this band of sky. Perseus looks like a Pi symbol (you will probably have to mentally rotate it), the size of your fist at arm's length.
While we are into comets, I recently dug into old night sky pictures I took years ago of the great comet Hale Bopp in 1997. It was an impressive comet, inspiring awe for its beauty, size and colored double tail (and also comet panic and mass cult suicide. Rings some bell ?). In 1997, photography was still a chemical film affair, so I created the digital image by scanning the printed film and adjusting the colors with a little GIMP to remove the strong yellow/green hue resulting from light pollution and film composition effects. Pics have been taken with my camera, a Nikon Nikkormat with a 125 mm lens and a 400 ISO film, mounted in a "parallel scope" position on my telescope (a 114/1000 mm Newtonian) with a self-built connector. With such configuration I could take long shots (some second or even minutes) by taking the picture with the camera, while at the same time carefully following a reference star with the telescope. This technique allows to counteract the Earth's rotation by hand, and obtain single spots of light instead of streaks. It takes some practice and tricks to setup the telescope mount properly and not introduce accidental vibrations, but the result is pleasing and (very important for a student) rather cheap. Unfortunately, only a really dark sky allows long exposure time and well contrasted result, and light pollution in Italy was (and still is) very high. This picture has been taken from the banks of a river, with some seconds of exposure time, then digitally imported and corrected
You can see a comparison against the original, non-corrected picture in the following image, on the right hand side. The strong yellow/green hue is evident, as well as the poor contrast and saturation
Another picture of the same subject, again with digital correction applied. I tried a nice shot with the cloud merging with the comet tail, a relatively successful attempt. I also got an airplane
Overall, not really great results (on the internet you will find much better pictures), but the original I took is much worse, and my skills with digital image correction techniques are basically nil. I also tried to remove light pollution by subtracting a blurred version of the image, but the result was unpleasant, resulting in a strong "halo effect" at the border between the trees and the sky.
- http://news.nationalgeographic.com/news/2010/06/100615-biggest-comet-mcnaught-sky-show-science-space/
- The Hale Bopp images I produced are released under CreativeCommons-Attribution.