Choosing a New Telescope – GoTo or not GoTo

Guide to Meade Telescopes

I am often asked by people “I’m a beginner, so what telescope should I buy?” Or more often, what GoTo telescope would I recommend for someone starting out in astronomy?

When venturing out and buying your first telescope, there are a number of factors to consider, but because of glossy advertising and our current digital age, the first telescope that people think of is a GoTo.

Do you really need a GoTo or would a manual telescope suffice? In order to make a good decision on what telescope to buy, you need to decide on what you want to use the telescope for — observing, photography, or both and does it need to be portable or not? This will help you make the best decision for the mount of your telescope.

GoTo telescopes are usually advertised as being fully automatic and once they have set themselves up, or are set up by the user, they can access and track and many thousands of stars or objects with just a simple touch of a button. These features have made GoTo scopes are very desirable with many astrophotographers.

Manual telescopes are not automatic or driven by motors as GoTo scopes are. They are predominantly used for observing (using your eyes instead of a camera) and the scope is moved by hand or by levers by the user to find different objects in the eyepiece. Manual telescopes usually have a finder scope, red dot finder or laser finder to aid in finding objects in the eyepiece. They are unable to track objects, which can make them unsuitable for photography.

GoTo Vs Manual
Compared to GoTo telescopes, manual telescopes are much more economical as you are basically buying a very simple mount and an optical tube assembly (the telescope tube, or OTA). With GoTo you are adding electronics and control mechanisms to drive the scope, which can add heavily to the cost. A small GoTo telescope could cost the same as a lot larger manual Dobsonian telescope.

Good GoTo telescopes make astrophotography very accessible and enjoyable, especially with the addition of cameras and other kits. As opposed to manual scopes, GoTos can be used for long exposure astrophotography. Be aware though, that much astrophotography is done with very expensive imaging equipment, but good results can be achieved with web cams and DSLR cameras.

Manual telescopes are brilliant at helping you discover and learn the sky as you have to actually hunt or star hop for different objects. I once met a person who had been using a GoTo telescope heavily for a year, and at a star party I asked her to show some kids where a well known star was with my laser pointer, she didn’t know because she was used to her GoTo scope taking her to objects.

So which one should you buy?
I would recommend for pure visual observing a manual telescope such as a large Dobsonian or Newtonian telescope. The human eye needs as much light to enter it as possible to see things in the dark, so a big aperture or mirror means greater light gathering and more light entering your eye, so you can see more. What you saved by not having GoTo, you can spend on increasing the size of your telescope.

If you want to add photography or imaging capabilities then I would definitely recommend a good quality GoTo scope or mount. You will get a smaller aperture compared to the manual scope for the same money, but the scope will track for astro-imaging and can also be used for visual observing. Be prepared to spend a lot more money, though.

Consider how you want to use your telescope and the size of your budget. Avoid buying low end, cheap, budget, or what is known as “department store” telescopes to avoid disappointment. Save up a little longer and get a good telescope. Visit your local astronomy store or telescope distributor and before you buy ask an astronomer, they will be glad to help.

I hope you enjoy your new telescope for many years to come 🙂

Dobsonian Telescope

How To See NanoSail-D From Your Own Backyard

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The night sky has many wonderful objects to look at on a clear evening, including many man-made satellites, and the always impressive International Space Station (ISS). Now there’s a new addition to these artificial delights: the first ever solar sail to orbit the Earth, NASA’s Nanaosail-D Satellite. Want to know how you can see it?

The 10m x 10m reflective sail is designed to act like a brake and gradually create drag in the upper atmosphere, slowly pulling a satellite down and de-orbiting it at the end of its working life. Nanosail-D is testing the potential of this technology to reduce space junk and debris.

NanoSail D. Image credit NASA

The satellite has a huge reflective sail and could potentially be many times brighter than the planet Venus when it catches a glint from the Sun. Unlike the International Space Station (ISS) and other satellites, the sail will not be visible when it is directly above us as we will be looking at it edge on, It will be more visible when closer to the horizon.

The Nanosail-D satellite will be visible from now and for the next few months. To see it you will need to know exactly when it will be visible from your location. To do this, go to heavens-above.com or spaceweather.com where star charts with times and pass details will be displayed after you enter your observing site.

Once you know the time and location in the sky of the pass of the satellite, make sure you are able to get a good view of the horizon, or part of the sky where the satellite due to appear. Give yourself plenty of time, go outside and get ready. I always set a 30 second reminder on my watch or cell phone, so I don’t have to fumble around or guess the time.

Unlike the ISS and most other satellites, Nanosail-D passes may only last a few, or a few tens of seconds, so make sure you are looking in the right place at the right time. You will see an amazingly bright star-like object rise up, get brighter and then suddenly disappear. When it “disappears” it is still passing over, it’s just no longer at the right angle or is no longer being illuminated by the sun. NanoSail-D has few reflective surfaces compared to many on the ISS.

To enjoy the Nanosail-D passes:

• Make sure you know the right place in the sky and the time of the pass, by checking on the web.
• Make sure you will be able to get a clear view of it from your viewing location.
• Set an alarm or get ready for the pass as it only lasts a few seconds.
• NASA expects NanoSail-D to stay in orbit until April or May 2011.
• If you are an astrophotographer, don’t forget, NASA and SpaceWeather.com are having an imaging contest of NanoSail-D. Find out more here.
• Most of all, get your friends and family outside with you to watch Nanosail-D and enjoy!

Travel Destination: World’s First Dark Sky Island

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Looking for a great vacation spot with those all-important dark skies for astronomical observing? A small island in the English Channel off the French coast of Normandy might be just what you are looking for. The Channel Island of Sark has been officially recognized for the quality of its night sky by the International Dark-sky Association (IDA), who have designated it as the world’s first dark sky island, the latest in a select group of dark sky places around the world.

An aerial view of Sark.

What makes the Sark skies so dark? The island has no public street lighting, there are no paved roads and cars, so effectively, there is no light pollution in the skies. Those who have been there say the night sky is very dark, with the Milky Way stretching from horizon to horizon, meteors streaking overhead, and countless stars on display.

The people who live there have made dark skies one of their priorities. Through a long process of community consultation, a comprehensive lighting management plan was created by Jim Patterson of the Institute of Lighting Engineers, and many local residents and businesses have altered their lighting to make them more dark sky friendly, ensuring that as little light as possible spills upwards where it can drown out starlight.

Roger Davies, president of the Royal Astronomical Society, said, “This is a great achievement for Sark. People around the world are become increasingly fascinated by astronomy as we discover more about our universe, and the creation of the world’s first dark sky island in the British Isles can only help to increase that appetite. I hope this leads to many more people experiencing the wonders of a truly dark sky.”

For more information on Sark, see the island’s website.

For more information on the International Dark-sky association: http://www.darksky.org/

Source: Royal Observatory Greenwich

Win iPhone App for Observing: TeleCalc

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There’s a new observing app for the iPhone, iPod and iPad, called TeleCalc. Enter in two data points about your telescope (aperture and focal ratio) and two about the eyepiece (focal length and diameter) the program calculates angular field of view, best eyepiece magnification, resolution (Dawes, Rayleight), exit pupil, limiting stellar magnitude and light gathering power.

TeleCalc is available in eight languages: English, Spanish, French, Italian, German, Portuguese, Russian and Japanese. Search “TeleCalc” in iTunes to download it or find it on the iTunes store.

Thanks to developer Fabio Rendelucci who has given Universe Today 3 free TeleCalc apps to give away.

The first 3 people to answer the following question will be sent a code for a free TeleCalc app:

To find the magnifying power of any telescope, divide the focal length of the telescope by the focal length of the what other telescope piece?

Submit your answers in the “Comments”

Also, if you’re looking for more, take a look at all the apps that NASA has available for both iPhone and Android.

Astronauts Open New Window on the Universe

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“Let there be light! Cupola windows open toward Sahara desert. Priceless!” Tweeted ISS astronaut Soichi Noguchi from the ISS.

It’s the moment we’ve all been waiting for: the opening on the windows of the new Cupola on the International Space Station. And it was incredible.

“As expected, the view through window seven is absolutely spectacular,” ISS commander Jeff Williams said. “When we have the others around it open, it will give us a view of the entire globe. Absolutely incredible.”

Shutters are opened on the new Cupola on the ISS. Credit: NASA TV

The new $27 million bay window was uncovered during the third EVA of the STS-130 mission by spacewalkers Nick Patrick and Bob Behnken, who removed the protective launch covers and bolts. Then, from the inside, each of the seven shutters was cranked opened and closed one at a time, to test the view — and the shutters. In case there were any problems, the astronauts out on EVA could help close the shutters.

Later, all the shutters were opened at once for the full view. “I don’t think space station’s ever going to be the same after this,” Mission Control radioed to the ISS.

The new observation deck will allow astronauts unprecedented 360-degree views of Earth and space, while providing a new location for robotic operations where astronauts inside the ISS can actually watch directly what they doing with the CanadArm2 on the ISS, instead of completely relying on computer inputs and camera views. The Cupola is attached to the nadir, or Earth–facing port of the new Tranquility node, a $380 million addition to the station that was delivered to the ISS on the current space shuttle mission.

Built by the Italian space agency, the Cupola is 1.5 meters (5 feet) tall and about 3 meters (10 feet) in diameter. Six rectangular windows encircle the dome, with a large circular window in the middle.

Mission managers said at a press conference last week that the windows will remain shuttered most of the time to protect the 4-pane fused silica glass from micrometeroid strikes. The large central window shutter may be allowed to opened more frequently since it is facing towards Earth and away from potential incoming space debris.

Nancy peeks through a model of the Cupola that was at Kennedy Space Center. Image by Robin Hobson.

A model of the Cupola was set up at the press room at Kennedy Space Center. I asked about the windows and the potential of problems if they are hit by micrometeroids, and was told that if the windows are dinged or significantly damaged, they can be repaired or replaced on orbit. There are spare window assemblies built, but they aren’t currently on the ISS nor are there plans to bring them up, for now. For minor damage, the shutters would be closed until the repairs could be done. For major damage, the Cupola has a hatch, so there is the potential to close off Cupola, but mission managers said that option has a very low likelihood of occurring.

Asteroid Might be Visible to Naked Eye on Feb. 17

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An asteroid could be visible with binoculars, or even the naked eye on Wednesday, February 17, 2010. No, it’s not coming close to Earth, although this second most massive object in the asteroid belt will be at its closest point to Earth in its orbit, about 211,980,000 kilometers (131,700,000 miles) away. Asteroid Vesta – one of the asteroids that the Dawn spacecraft will visit – will be at opposition on Wednesday, meaning it is opposite the sun as seen from Earth, and is closest to us. Vesta is expected to shine at magnitude 6.1, and that brightness should make it visible for those with clear skies and a telescope, but perhaps even those blessed with excellent vision and little or no light pollution. Vesta will be visible in the eastern sky in the constellation Leo, and will continue to be visible — although less so — in the coming months.

What makes this space rock so prominent these days? Along with its relative proximity at this point, a full half of the asteroid is being bathed by sunlight when seen from Earth, making it appear brighter. Another attribute working in the observer’s favor is that Vesta has a unique surface material that is not as dark as most main belt asteroids – allowing more of the sun’s rays to reflect off its surface.

For more info about observing Vesta, check out this article from Sky & Telescope.

If you get lucky enough to see Vesta, and want to learn more about it, check out this info on the Dawn mission website. Dawn is currently motoring its way through the asteroid belt, will begin its exploration of Vesta in the summer of 2011.

Source: JPL

Big Full Moon and Mars Put on a Show Friday Night

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If your skies are clear on Friday night, January 29, 2010, take advantage of one of the skywatching highlights of the year. A full Moon and Mars will be putting on a show, and the pair will be prominently close to each other in the sky. Plus, this Friday night’s full Moon is the biggest and brightest full Moon of the year. It’s a “perigee Moon,” as much as 14% wider and 30% brighter than other full Moons you’ll see later in 2010, according to Spaceweather.com. And, even though you’ve likely not gotten an email from an excited acquaintance relaying that Mars is really close to the Earth now — that is the case. Mars is at opposition on the 29th, which means it lines up opposite the Sun and is now the closest to Earth their orbits, and so will shine brighter.

The image above of the not-quite-full Moon from January 27, 2010 is shared by Universe Today reader Alan Walters, from Florida. You can see more of his wonderful photography of the night sky, launches and shuttle landings, Florida wildlife and more at Alan Walters Photography.

Positions of the Moon and Mars. Credit: McDonald Observatory

This image, courtesy of Stardate Online and the McDonald Observatory, shows the positions of the Moon and Mars in the night sky the next few evenings.

This is not a great opposition for Mars because it occurs around the time that Earth is closest to the Sun and Mars is farthest. The gap between the two planets will be a hefty 62 million miles (99 million km). The smallest possible distance at opposition is about 35 million miles (56 million km), which happened a back in August of 2003, and prompted the infamous emails that now surface every August, that Mars would be as big the full Moon, which of course, is not — and was not — true. Mars appeared more than twice as bright then as it will this year, but was still a star-like dot in the sky.

JPL is sponsoring a Facebook Event, Friday Night With the Moon and Mars, to heighten awareness of what a great sight it will be; plus its a great way to share in the experience with others online.

And for more information, see this [email protected] article about the close encounter.

Sources: Stardate, Spaceweather.com

Epsilon Aurigae Eclipse Mystery Solved with Your Help

If you’ve been helping out with the Citizen Sky project to monitor Epsilon Aurigae, then congratulations – the first of the results are in! Donald W. Hoard, a research scientist at Caltech announced the findings at the American Astronomical Society meeting in Washington, D.C. this morning. We invited our readers to participate in monitoring the star in August of 2009, and combined with observations from Spitzer, a 200-year old mystery has potentially been solved.

Epsilon Aurigae is a bright star in the constellation Auriga. It began to dim in brightness last August, which it does every 27 years. The star dims for over 2 years, with a slight brightening in the middle of the eclipse, making it the longest known orbital period for a stellar eclipse. The Citizen Sky project invited professional and amateur astronomers alike to aid in the observation of the star during this eclipse.

What exactly passes in front of the star was a mystery, though it was thought that a large disk of material with two stars orbiting tightly in the center is the cause of the eclipse. The disk itself is pretty huge – on the order of 8 astronomical units. There is a slight brightening during the middle of the eclipse that led astronomers to believe there is a hole created by the two stars in the center.

“If [Epsilon Aurigae] were an F star, with about 20 times the mass of the Sun…a single B star at the center of the disk doesn’t have enough mass to explain the orbital dynamics,” Hoard said. Other possibilities proposed were the presence of a black hole at the center of the disk, but there were no telltale X-rays coming from the system that would show a black hole was heating up matter in the disk.

Through observations by astronomers that participated in the project, as well as observations made by the Spitzer space telescope, a major revision of the properties of Epsilon Aurigae itself were in order.

“What we were most pleased to find an answer to… was that the results strongly tip towards a 2 solar-mass dying star. Sometime in the next few thousand years it will emerge as a planetary nebula,” Hoard said.

This means that instead of being a 20 solar-mass F-star supergiant, Epsilon Aurigae is in fact a 2 solar-mass F-star which is in the last stages of its life, and thus giant in size – about 300 Suns across. This, combined with a single B-star of about 5.9 solar masses at the center of the disk that orbits Epsilon Aurigae fit the observations very well, Hoard said.

Arne Henden of the American Association of Variable Star Observers (AAVSO), commenting on Hoard’s presentation at the press conference, said “Don says that we solved it, and I disagree. We need to determine the nature of the dusty disk that is involved – these are things that you see around young stellar objects, not older stellar objects.”

Hoard said that there was a curious property of the disk in that it was composed of larger grains of dust – more like grains of sand than microscopic dust motes.

“The observations that are being made by Citizen Sky project…will hopefully help answer this by providing answers about the composition of the disk and the temperature zones as the eclipse continues. We have these results in large part due to the effort of this huge group of citizen astronomers that are observing Epsilon Aurigae,” he said.

Epsilon Aurigae is still undergoing its eclipse, though the first phase ended right around the New Years Eve 2009. It will continue to be dim until early 2011, when it will begin to brighten again. There is still a lot to be answered about this system, and your help is needed, so keep (or start) observing and reporting! For more information on how to do so, visit Citizen Sky.

Source: AAS press conference on USTREAM, Citizen Sky press release

Altazimuth

Altazimuth is a contraction of altitude-azimuth; in astronomy it most often refers to a type of telescope mount (and is sometimes called alt-az), but it can also mean a coordinate system.

Altitude means the angular distance above the horizon; straight up (overhead) is 90o (and is called the zenith). Azimuth is also an angular distance, measured clockwise from north (so east is 90o). Any point, or direction, in the sky has one – and only one – altitude and azimuth; in other words, the altitude and azimuth are the coordinates of the point (on the celestial sphere).

An altazimuth telescope mount is one that can move separately in altitude (up and down, vertically) and azimuth (side to side, horizontally). Small telescopes used by amateur astronomers tend to have altazimuth mounts; larger ones tend to have equatorial mounts … unless they are Dobsonian. Why? Because while alt-az mounts are generally cheaper, tracking astronomical objects (like stars) is much easier with equatorial mounts.

Historically, the telescopes used by professional astronomers did not have alt-az mounts, because automatic tracking was impossible. As computers became powerful and cheap enough, they could be used to control the motors on each axis of an altazimuth mount; today, almost all ground-based astronomical telescopes have altazimuth mounts, whether optical, radio, or even high energy gamma ray! The first really large optical telescope to use an altazimuth mount is the 6-meter Bol’shoi Teleskop Azimultal’nyi, in Russia.

Universe Today’s Telescope Mount, Telescope Parts, Telescope Tripod, and How To Use a Telescope are great resources for learning more.

The Astronomy Cast episode Choosing and Using a Telescope covers the benefits of alt-az mounts (vs equatorial), and Telescopes, the Next Level gives insight into tomorrow’s professional ones.