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Spring2003 2010 Spring Volume XIII Number 2 2 Volume VI Number For Me? You Shouldn’t Have! By Robert Davis I had a very good birthday this year. Friends and family got together and a good time was had by all and NASA launched a new solar observatory in my honor. Maybe they didn’t really launch in my honor but it was on my birthday which is pretty cool. This new solar observatory is called SDO: Solar Dynamics Observatory and it was launched on February 11, 2010. (You might want to make a note of the date for next year.) According to the mission’s website, “SDO is designed to help us understand the Sun’s influence on Earth and Near-Earth space by studying the solar atmosphere on small scales of space and time and in many wavelengths simultaneously”. I guess one could say it will shed some light on sunlight. SDO will be in an orbit 36,000 km (about 22,400 miles) above the Earth. The orbit will be an inclined geosynchronous orbit which will allow for continuous observations of the Sun. There are other orbits that would have achieved the same viewing capabilities but the other reason for the geosynchronous orbit is that it allows for a single dedicated ground station to receive the tremendous amount of data that SDO will be transmitting. SDO will have a continuous science downlink rate of 130 Megabits per second. It is going to need that bandwidth to transmit all the imaging data that it will generate because SDO will be taking a whole lot of pictures. How many pictures? Stay tuned. Public Viewing at Robert Ferguson Observatory April 24, Saturday Public Solar Observing Public Observing Night noon – 4 pm 9 pm May 15, Saturday Public Solar Observing Public Observing Night noon – 4 pm 9 pm June 5, Saturday Public Solar Observing Public Observing Night June 12, Saturday Public Solar Observing Public Observing Night July 10, Saturday Public Solar Observing Public Observing Night solar magnetic field lines We’ve all heard about solar wind, solar flares and coronal mass ejections (CMEs). We’ve heard about Sun spots and the 11 year Solar Cycle. All of these phenomena occur because the Sun is a very active object and sometimes it is more active than others. Scientists have some ideas about how the Sun works and why space weather happens but they don’t have a very good handle on how to predict how the Sun will behave in the future. Being able to predict solar activity is important because there are currently (turn to SDO Page 7) http://www.rfo.org noon – 4 pm 9 pm noon – 4 pm 9 pm noon – 4 pm 9 pm Evening public viewing is $3 per adult, 18 years or older, plus $8 per car State Park fee. Donations accepted. Dress for cold nights! For current observatory information call (707) 833-6979. RFO Classes (see Page 3) Night Sky Spring/Summer Series April 6 & 13 June 8, 15 & 22 July 6 & 13 August 10 Observing Labs Star Formation: June 13 Star Death: September 6 State Park Closure Update Although Sugarloaf Ridge State Park is closed three days a week, this closure is not affecting observatory operations. Dates that RFO is open are special events; docents and visitors are able to access the observatory. Page 2 Focused A quarterly newsletter published by: The Valley of the Moon Observatory Association P.O. Box 898 Glen Ellen, CA 95442 707.833.6979 www.rfo.org Editor: Publisher: Derek Braud Colleen Ferguson Contributors: Robert Davis Colleen Ferguson Loren Stokes Jack Welch President's Message Subscriptions Fill out & mail form on back page or subcribe online at www.rfo.org (see Join Us!) Advertising Contact the editor, Derek Braud: [email protected] Submission Guidelines Unsolicited submissions are welcome and will be published at the discretion of the editorial staff. Send submissions to the editor, Derek Braud: [email protected] VMOA Mission Statement The VMOA is a group of volunteer amateur and professional astronomers organized as a nonprofit association to provide educational programs about science and astronomy for students and the public. To that end, the VMOA operates the Robert Ferguson Observatory in Sugarloaf Ridge State Park in association with California State Parks. VMOA Board of Directors President: Vice President: Treasurer: Secretary: Members: Colleen Ferguson Larry McCune Steve Peterson George Loyer David Cranford Rob Davis Mark Hillestad Bill Russell Gordon Spear Steve Smith by Colleen Ferguson After a long, wet winter the skies above RFO are clear and dazzling for spring. Sugarloaf Ridge State Park by day is filled with colorful wildflowers, brilliant green hills and whitewater streams. Recent solar viewing shows that our sun is becoming active again, bouncing up from the bottom of the 11-year solar cycle. After many Saturday afternoons explaining to the public what an amazing and rare sight they were seeing – a spotless disk – the solar astronomers are looking forward to pointing out solar phenomena again. The increase in solar activity is turning into a new goal for RFO: acquiring a Coronado 90 solar telescope. The Coronado 90 will provide incredibly sharp, high-contrast h-Alpha views that can reveal detail and structure and produce stunning visual and photographic images. It is used around the world by serious solar enthusiasts and professional research facilities. In a rave review of this telescope at nightskyobserver.com, author Kevin Berwick pointed out that the sun is completely unaffected by light pollution and that with this scope we can view prominences every day without waiting for a total eclipse and paying the high cost of travel. Here’s an excerpt from the portion of the Spring 2010 review titled First Light: “The overall impression, particularly at low power, is that the Sun is transformed from a harmless outdoor light into a seething ‘Death Star’. You really do get an appreciation of the fact that what you are witnessing is a contained thermonuclear explosion.” His only regret was that he did not buy one sooner so that he wouldn’t have to wait so long for the next solar maximum. We’re starting fund raising now in hopes that we can raise $10,000 and start enjoying the sun’s increasing activity with an awesome new solar scope. Meanwhile the amazing team of telescope makers designing and constructing Project 40 are making great progress. The large primary mirror is going through the final stages of testing and polishing and the secondary mirror is being ground. Parts for the drive mechanisms are arriving and being tested. Minor details are being added to the design drawings to make sure everything will work together as the telescope starts to be assembled. After so long in the planning stages this project is really coming together! Thanks to everyone who is giving their time, technical talents, and funds to make this dream a reality. Please join me in welcoming two new members to the VMOA Board. Many Focused readers are familiar with Rob Davis since he writes entertaining and informative articles for most editions. He is also the highlight of most of our docent meetings at RFO, sharing “What’s Going On Out There” with a mix of technical information and just plain fun. Rob often volunteers for private and public events at RFO. Steve Smith was the winner of the first “Docent of the Year” award, presented in 2009. Although he flirts with other RFO telescopes the CCD seems to have captured his heart. Steve volunteers for almost every event at RFO and so he Spring 2010 Page 3 2010 RFO Class Schedule Night Sky Spring/Summer Series Each class includes a lecture on the constellations of the season, their history and mythology, and how to find objects within them. Learn the bright stars, deep-sky objects, and visiting planets of the season’s skies. After each presentation (sky conditions permitting), you will enjoy a review of the constellations in the actual night sky and learn how to find them for yourself. The constellations, and the objects within them, will be viewed through binoculars and telescopes, including the Observatory ’s 24-inch reflecting telescope, until or beyond 10:30 pm (depending upon interest and enthusiasm). The remaining Spring Series classes will be held on Tuesdays at 7:30 pm on: April 6 & 13 The opcoming Summer Series classes will be held on Tuesdays at 7:30 pm on: June 8, 15, & 22, July 6 & 13, and August 10 Fee: $75 for 6-class series or $23 for a single class E-mail: [email protected] to reserve a space in this popular class Observing Labs An intensive telescope observing session after a brief presentation on the night’s theme. Handouts/Observing lists provided. Attendance limited to 6. Star Formation: Diffuse Nebulae, Star Formation, and Open Clusters Sunday, June 13, at 8:30 pm [Raincheck date: none] Star Death: The End of Stellar Fusion Monday, September 6, at 7:00 pm [Raincheck date: none] Fee: $30. For reservations, email: [email protected] brings to the board a wealth of knowledge about current observatory operations. Another new happening for RFO is creation of a ‘facebook’ page. If you’re an active ‘facebook’ user check it out! Just search for the group Robert Ferguson Observatory and become a fan. I continue to be very impressed with the generosity and talent of the volunteers that make the observatory the incredible place that it is. Thanks to all of the docents - those who interact with the public at our events and those who work behind the scenes - as we go into the busy observing season ahead. You are all awesome! Please include your mailing address and phone number. If you have any questions, please contact June Have you been wishing that you had a Ferguson at (707) 762-7064 or garment with the RFO logo? You can [email protected]. have the RFO logo embroidered on New! Subscribe, Renew and your own shirt, hat or lightweight jacket. Donate Online The garment should have no seams or pockets to interfere with the VMOA supporters now have the option embroidery. The embroidery will be of subscribing, renewing their placed in the upper left side of the subscription or making a tax-deductible donation online. garment unless otherwise requested. Just send your garment Visit: www.rfo.org before April 30, 2010 to: So I walk on uplands unbounded, and June Ferguson, 809 Gilardi Drive, know that there is hope for that which Petaluma, CA 94952 and enclose Thou didst mold out of dust to have $8.18 for the embroidery and sufficient consort with things eternal. funds for return shipping. -The Dead Sea Scrolls RFO Logo Embroidery Available Page 4 Spring 2010 Watching the 2010 Spring Sky by Jack Welch Saturn begins this spring at opposition in Virgo on 3/ 21. The rings are still at a small angle, 3.2°, after Earth crossed the ring plane last year. The angle will decrease to a minimum of 1.7° in late May, then begin increasing again. All this spring will be the best time for observing Saturn in telescopes so it is clearly the star of the show! Saturn ends retrograde motion on 5/31. Mercury provides its best evening appearance of 2010 from about 3/25 to 4/15, though Mercury dims substantially during the last few days of this period, and the brighter Venus is nearby throughout Mercury’s brief appearance. Best viewing is during the first week of April. Start looking for Mercury in the west around 8:00pm. Mercury will also provide a poor morning apparition from about 5/22 to 6/13 when it will be low in the east about 30 minutes before sunrise. Look for it at about 5:15am. The crescent moon will be above Mercury on 6/10. And a very thin 1.2% crescent moon will be north (left) of Mercury on 6/11. Venus is the “Evening Star” all this spring and through most of the rest of 2010. It will rise before twilight by the end of April, becoming more prominent. The crescent moon joins Venus on 4/15 and 16 (see illustration). While a challenge, try to spot the now dim Mercury below the crescent moon on 4/15 using binoculars or a telescope. Note that on 4/16 the crescent moon will be very near the Pleiades (M45). Use binoculars to spot the Pleiades stars in the twilight sky. The crescent moon again joins Venus on 6/14 (see illustration). Note that Mars and Regulus are a bit higher in the same view and that Venus is nearing M44 in the middle of Cancer. Venus will be very near the Praesepe (M44) star cluster on the evening of 6/19. Start looking in late twilight around 10pm and use binoculars. The pair will drop to less than 6° above the horizon by the end of twilight at 10:34pm. Mars is in the western evening sky all spring. It is now fairly far away and small so no longer a worthwhile 12 telescope target. But it remains a bright and colorful sky decoration. In mid-April, Mars passes just north of Praesepe (M44), with the closest approach between the 14th and 18th. Observe them around 10pm and use binoculars. On the evening of 6/5 Mars, at magnitude 1.1, will be very near the bright blue star Regulus in Leo, at magnitude 1.4. This should be a lovely colorful pairing in binoculars and can be appreciated for several days before and after. Look for them around 10pm. Jupiter has emerged into the morning sky, rising during twilight during most of April, then before twilight and climbing higher after April. At 6:00am on 4/11, Jupiter will be below the crescent moon, 6° above the horizon a bit south of east. The next morning a 4% crescent will be to the left (north) of Jupiter, both at low altitude. At 4:30am on 5/9 the crescent moon will again be above Jupiter, which will be at 7°. Finally, at around 4am on 6/6 the moon will again be near Jupiter. Spring 2010 Page 5 a while later, though well before the moon enters the umbra at 3:17am. At that time the moon will still be quite high in the southwest. Maximum eclipse is at 4:38, early in nautical twilight while the moon will still be 11° high. The eclipse will still be in progress when the moon sets around 5:53. The solar system has a few other events to watch this spring. On the evenings of 4/12 and 4/13, we can try to spot a couple of comets. The Comet C/2009 O2 (Catalina) will be very near the star upsilon Tauri amidst the Hyades open star cluster! Look for it in the west around 9:30pm after twilight but before it drops too low in the west. Later, at about 10:30pm, look for Comet 81P/Wild in the vicinity of the star iota Virginis. A finder’s chart will probably help in this latter case. Both comets should be somewhere around 9th magnitude, so a telescope is necessary. However, binoculars are also worth Besides the moon pairings already mentioned, the moon will be near the bright red star Antares in Scorpius at about 4am on 4/3, 10pm on 5/28 (though it will be easier to see if you wait later for it to rise higher), and at 2am on 6/ 24. At 8:00pm on 4/14 we have a nice chance to see an ultra-thin 0.6% crescent moon. It will be only 4° above the horizon 17° north of due west. You will need binoculars to help pick it out of the twilight glow. It will set quickly, so timing is important. A thin 1.5% crescent will be 7° high 25° north of west at 8:45pm on 5/14. You will have more time to catch this very thin crescent, but use binoculars again. At about 10:50pm on 5/17 the moon will occult the magnitude 5.9 star 61 Geminorum. It will disappear behind the dark limb of a 20% crescent 29° from the southern cusp. The moon will be 13° high in the west-southwest. Next, there will be a 3.9% crescent moon at 9:30pm on 6/ 13. Finally, the moon saves its most dramatic display for a few days into the summer. The full moon the morning of 6/26 will experience a nice partial (about 50%) lunar eclipse. The moon enters the penumbra at 1:58am. This is a subtle event and the eclipse won’t become noticeable until a try. Finally, two of the brighter asteroids are at opposition this spring. Pallas is first on 5/4 in Serpens. Look for it at magnitude 8.7 about 2.5° south of the star Alphekka in Corona Borealis. Ceres comes next on 6/18. It will be at magnitude 7.2 in Sagittarius. Consult a finder’s chart. Spring officially begins at the Vernal Equinox at 10:32am on 3/20 this year, and ends at the Summer Solstice at 4:28am on 6/21. Try to get your eyes to a telescope or two during that time to see some of the spring’s lovely objects, such as the “Black Eye Galaxy” (M64) or the “Sombrero Galaxy” (M104) or the “Turtle in Space” planetary nebula (NGC6210) or any of the many gorgeous globular clusters visible this time of year! All and more are reason enough to visit RFO. We’ll see you there! Which city is faster paced: New York or Los Angeles? If you look at the difference in latitude between the two, New Yorkers spin around the Earth at about 775 mph, while Angelinos spin at about 850 mph. For the ultimate in fast paces try an equatorial habitat, where one can spin at the top Earthly rate of 1,038 mph. Page 6 Spring 2010 Etendue and the LSST By Loren Stokes The Large Synoptic Survey Telescope (LSST) is currently being constructed and should see first light in 2015. Its primary mission is to detect and determine the orbits of near-Earth asteroids that could cause regional devastation if they ever strike Earth. The telescope’s primary mirror is 8.4 meters in diameter, and its huge 3,200 megapixel camera will see nearly ten square degrees of sky at once. Located in northern Chile, it will take a 15 second exposure every 20 seconds. It will cover the entire sky every three nights with a sensitivity of magnitude 24.5. This sensitivity should allow detection of asteroids as small as 100 meters. By repeatedly measuring the entire sky every few nights, asteroids can be discovered by their movement relative to the fixed background stars. They will be found automatically by computer. Over long periods of positional measurement, the orbits of newly discovered asteroids can be calculated with better and better accuracy. The Figure of Merit of such sky survey telescopes is called etendue, which is French for “extent.” It is the light collecting area of the telescope (in square meters) multiplied by the area of its camera’s field of view (in square degrees). This Figure of Merit describes how quickly a telescope can image the entire sky. A large light collecting mirror means short exposure times of the digital camera. A large field of view means fewer exposures are needed to cover the entire sky. To appreciate how amazing is the design of the LSST, we need to look at the etendue of typical telescopes. Let’s start with the RFO’s 14-inch robotic scope. The primary mirror has an area of about 0.1 square meters. The field of view of the digital camera is about 0.2 degrees across (40% the diameter of the full moon), and the viewing area is the square of this, 0.04 square degrees. The etendue is therefore 0.1 square meters times 0.04 square degrees, or 0.004 (in units of square meters square degrees). Note that simply doubling the telescopes primary mirror diameter does not change the etendue if the same focal ratio and same camera are used. Doubling the mirror diameter increases the light collecting area by four, but doubling the focal length means the camera sees one half as much field of view and one fourth as much viewing area. So the etendue remains unchanged. To increase the etendue we need a telescope with a lower focal ratio. Consider a 10-inch f/4 reflector with a camera using the largest available amateur CCD chip, 36 x 36 mm. The primary mirror has an area of about 0.05 square meters. The camera field of view is 2 degrees and has a viewing area of 4 square degrees. The etendue is therefore 0.2, which is 50 times greater than that of the 14 inch scope. This camera attached to the RFO’s 24-inch f/4.5 Newtonian telescope (primary mirror area of 0.29 square meters) would have a field of view of 0.75 degrees and a viewing area of 0.56 square degrees. The etendue would be 0.16 which is less than that of the 10-inch f/4 telescope. Etendue decreases as the square of the focal ratio. The LSST uses an 8.4 meter diameter primary mirror with a focal ratio of 1.18. The secondary mirror is f/-1 and the tertiary mirror (the inner 5 meters of the primary mirror) has an amazing focal ratio of f/0.83. Three lenses before the camera correct for off-axis distortion. The camera is a mosaic of CCD chips measuring 64 cm (25 inches) across and is bigger than a refrigerator. The field of view is over 3 degrees and the viewing area is 9.6 square degrees. The light gathering area of the annular primary mirror is 33 square meters. The etendue is an astounding 320. This is 1,600 times that of the 10-inch f/4 example above. Current dedicated sky survey telescopes have primary mirror diameters of 1 to 4 meters and an etendue range of 5 to 50. The LSST etendue is nearly ten times larger. (Continued on next page) Spring 2010 (Continued from previous page) Within eight years of operation, the LSST should find 90% of near-Earth asteroids larger than 140 meters and determine their orbits. Other asteroids, comets and icy objects beyond Neptune should be discovered. As a bonus, by frequently imaging the entire sky, transient events outside our solar system and galaxy should be discovered. It is expected that so many events will be found that amateur astronomers will have ample opportunity to follow up using their telescopes and CCD cameras. Page 7 variability and how the physical processes inside the Sun are related to surface magnetic fields and activity. Remember all those pictures we mentioned earlier? That is where AIA comes into play. AIA will image the solar atmosphere in multiple wavelengths to link changes in the surface to changes in the interior. It will be observing in 10 different wavelengths and will snap a picture every 0.1 seconds. Ten images a second – one in each of the ten wavelengths! So with all of that data to work with it may not be too long before our favorite weather website will not only be able to tell us if we should go to the beach on the weekend but also whether or not we should launch a satellite. For more information about the LSST visit http://www.lsst.org/lsst (SDO: from Page 1) over 2,000 satellites in orbit around Earth and all but one is man made. The Sun could wipe out a whole lot of them with a big enough ‘hiccup’. A large CME aimed directly at Earth would send a large cloud of charged particles our way and wreak all sorts of havoc. Power grid failures could occur and the GPS system could go down leaving untold millions of people wandering around lost for days. This would just not be a good thing. So scientists would really like to gain a better understanding of what makes the Sun tick. They would like to understand it so well that they would be able to predict the Suns’ behavior. One of the ways they hope to gain this understanding is by observing the Sun in greater detail than has ever been done before and thus SDO was created. SDO has three main instruments on board: the Helioseismic and Magnetic Imager (HMI), the Atmospheric Imaging Assembly (AIA) and the Extreme Ultraviolet Variability Experiment (EVE). EVE will be measuring the extreme ultraviolet spectral irradiance (basically the energy radiated from the Sun in the ultraviolet wavelengths) to better understand its influence on Earth’s climate and near-Earth space. HMI is designed to cover the full disk of Sun but at a resolution 50% greater than what SOHO is capable of. HMI will be studying the photosphere and solar oscillations in an effort to better understand the interior sources and mechanisms of solar For more information about the SDO visit http://sdo.gsfc.nasa.gov/ SWEET DONATION FROM DOCE LUNAS RESTAURANT In the last issue of ‘Focused’ we announced that the nearby restaurant Doce Lunas offered to donate $1 to the RFO for every dessert ordered during the month of December 2009. Well, it turned out to be a sweet deal for the RFO as $280 was donated. Doce Lunas is just down the hill from the RFO in the town of Kenwood at 8910 Sonoma Highway. Incidentally, Doce Lunas can be translated to mean either ‘sweet moons’ or ‘twelve moons’ depending on the language root you use. How about ‘twelve sweet moons’, full moons, when the RFO is typically not open; can’t think of a better reason to get on over to Doce Lunas for something sweet! Thank you very much Jackie and Alex Purroy for your gracious, dare I say, sweet donation to the RFO. http://www.rfo.org Valley of the Moon Observatory Association support science education in your community NAME: ____________________________________________________________________________________ ADDRESS:_________________________________________________________________________________ CITY/STATE/ZIP CODE:__________________________________________________________________ PHONE: ______________________ $______ EMAIL: ___________________________________________________ SOLAR SCOPE DONATION $______ GENERAL DONATION ANNUAL SUBSCRIBER LEVELS: $20 $35 $50 $75 SUBSCRIBER STATUS: STAR NOVA BINARY CONSTELLATION Children under 16 Individual Couple Family GIFT NEW PREFERRED COMMUNICATION: GIFT FROM : EMAIL RENEWING POSTAL SERVICE ____________________________________________________________________ Subscribe or donate at www.rfo.org or make checks payable to VMOA, PO Box 898, Glen Ellen, CA 95442 VMOA P.O. 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