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Membership Application Observing Schedule Observing Directions Members Photos Telescope Buyer's Guide Important Links Send us some... The Catskill Astronomy club has a selection of astronomy books to borrow. If you want to borrow a book, it can be brought to the next observation session or indoor meeting. To receive our newsletter with important scheduling announcements and current club events please send a blank email to... CAC Newsletter 
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A lot of people want to know how dim a subject can they see. This is based on a variety of factors.We describe this as the limiting magnitude, which is the faintest magnitude visable or recordable by photographic or electronic means, dependant on aperture, sky transparency, seeing (steadiness of the upper atmosphere, light pollution, and other factors) exposure (photographic) and sensitivity of the eye or recording apparatus. A program that will help you determine this is available here . Save the web page and this calculator program will work off-line. Visual magnitude, which is often confused with the phrase limiting magnitude, simply means the apparent brightness of an astronomical body as seen by the eye. In an urban area, stars with a visual magnitude of 3 might hardly be visable. In an subrban area, stars with a visual magnitude of 3 might be tough in one direction, but stars in another direction with a visable magnitude of 4 might be very easy to see. In the outer suburbs you might find the visual limiting magnitude to be around 5. In a somewhat rural area, with a fairly high elevation (less atmosphere to look through) like Walnut Mountain, it is a visual magnitude of 6. To get much better, you are going to have to travel a long way from even the small towns. Some of the great observatories of the late 19th century and early to mid 20th century were built in some of the best areas only to have their effectiveness significantly diminished by man-made light pollution of the mid to late 20th century.It would be a terrible thing if the 21st century swallowed up more of our dark skies. We can all do our part to slow the growth of light pollution. Of course, our moon is the most significant source of natural light pollution. Most astronomers prefer to do deep sky observing when it is at or close to new moon. Here is a program that will help you determine a locality's visual magnitude without taking in light pollution into account. Again, save the web page and this calculator program will work off-line. Finally, an understanding of term magnitude is necessary. Magnitude is the brightness of an astronomical body. Appearant magnitude 1 is exactly 100 times brighter than magnitude 6, each magnitude being 2.512 times brighter than the next. Magnitudes brighter than 0 are minus figures, thus Sirius is -1.4 and the Sun is -26.8. The faintest objects photographed excede magnitude 26. Amateur astronomers with the help of today's fairly inexpensive, large aperture optics and extremely sensitive digital cameras have routinely photographed objects as faint as magnitude 22, a domain of only large observatories 25 years ago. Visually, despite large aperture or ideal seeing conditions, we can not see much fainter than magnitude about magnitude 16. International Dark-Sky Association Do you want to protect and preserve our dwindling dark skies? As more and more development takes place, there is less dark sky available for amateur, student and professional astronomers. While most people can grasp other types of pollution, nearly no one is aware of light pollution. The The International Dark-Sky Association can help you and understand what can be done. Catskills Astronomy Club's Membership Application and brief Guide to Telescopes are available as Adobe Acrobat (.pdf) files. If you need Adobe Acrobat, please click here for a free download. Web Site By ICE |