Look at the mysterious antique above. It’s the orrery made by ancient Greek. This device is made of bronze and encased in wood. It was found by divers off the Mediterranean island Antikythera in 1900. Thus, it is also called Antikythera Mechanism.
It enabled astronomers in the second century BC to predict the movements of the Moon and Sun, along with lunar and solar eclipses. It could recreate irregularities in the Moon’s motion due to its elliptical orbit. It also helped Greek astronomers to predict the location of the known planet. I guess this was the tool that made ancient Greek astronomers GODlike.
This is an interesting question, isn’t it? I only know about this today and I want to share it immediately.
Larger Newtonian (reflector) has a faster focal ratio. As you know, focal ratio is the value of focal length divided by diameter of primary mirror (aperture). So, that means faster focal ratio telescope has a relatively shorter focal length. Why does a large Newtonian (eg. 8″ Newtonian) have a fast focal ratio? The focal length of the Newtonian and refractor is almost nearly the length of the telescope. If a 10″ (250mm) Newtonian has a focal ratio of 10 (f/10), the length of the OTA is most likely over 2.5m. How can a single person handle such a bulky telescope? That’s why large Newtonians are always built to be “fast”.
What about the small aperture Newtonian? Manufacturer always made them slower and the secondary mirror is directly involved in this matter. When a Newtonian has a large secondary mirror, its focal ratio will be smaller in value. If a Newtonian has a small primary mirror but relatively big secondary mirror, the center obstruction (CO) is too great which will results in lower contrast images as well as observing. However, a large Newtonian won’t have much lower images because its center obstruction is relatively small.
The same theory applies to refractor too.
Although I haven’t seen McNaught myself these days, the spectacular images around the webs pleased me very well. I have been collecting the best McNaught photos for my very own collection but sharing is always a better attitude. 
Enjoy!
New Addition!
Author: Kevin Crause
Location: Mossel Bay, Western Cape, South Africa
Date: 20 January 2007
Photo Details: Nikon D2X, 80mm lens, f/2.8, 20secs, ISO800
Description: This is probably the longest tail I have seen!
Continue reading ‘Best McNaught Photos! [Updated!]‘
McNaught C2006/P1 continues brightenning and it’s now visible at daytime sky! Isn’t it really amazing? It’s now the brightest comet in 40 years and continue challenging the Ikeya-Seki in 1965 to be the brightest comet in centuries!
Go outside and stand in the shadow of a building so that the glare of the sun is blocked out. Make a fist and hold it at arm’s length. The comet is about one fist-width east of the sun. This is the instruction by SpaceWeather.com Beware of the sunlight, it will cause severe damage to your eyes if you stare at it with your naked eyes.
No astronomer is going to keep himself in front of the monitor when this super duper comet shows up. McNaught 2006/P1 is brightenned so rapidly as it nears the Sun. From what I see from the photos taken by amateur astronomer, the short exposure photos are really breathtaking! It’s short exposure! That means the our sights are quite similiar to the photos. Below is the skymap by Space Weather.
After I get the permission from the author of the photos, I will post them up here.
Omega AstroFilters is the supplier of NASA Hubble Space Telescope filters and the Mars Rover. So, you know that there is no doubt of the quality issue. I can’t say much on this though as I haven’t tried their filters yet. Hopefully, I will get a free Mars Rover poster.
I will get a NPB, Narrow Pass Band Nebula Filter. It’s a Ultra High Contrast type filter which is great for observing small and fainter emission planetary and nebula and a variety of bright nebula.
What’s more they have? VHT (Very High Throughput Nebula Filter) designed for small scope, HPOIII (High Performance OIII) for emission and reflective nebula and GCE (Galaxy Contrast Enhancement Filter) for galaxies.
Visit them at Omega Astrofilters!
It’s so interesting to disassemble a telescope especially those have a very precise and big gears. I’ve disassembled my computer since I was 8 and 8 years later I disassembled my LX90. I will tell you how to do so step-by-step. However, take it at your own risk, I will not responsible for any damage done to the telescope. I suggest that you read all the procedures before you do anything. If possible, read one more before you start and it’s advisable to print this article with you or leave your monitor on when you are doing your work.
Continue reading ‘Remove The Corrector Plate Of LX90′
Attributed to the damaged submarine cable (Asia Pacific Cable Network 2) which plays an important role in Asia internet, I was unable to access my blog hosted in U.S. That’s why the blog wasn’t updated for week.
In this period, I have removed the corrector plate of my LX90 and pictures will be posted soon with guidelines. The process was quite scary to me.
A good news here. This blog will be optimized soon for a better reading environment.
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