FROM THE PRESIDENT ! Bill Hanagan

~ Two Mini-Talks: NASA Solar Missions by Bill McKibben and

The Greenwich Observatory by Jim Barkley ~at the Mt. Cuba Astronomical Observatory

Next Meeting � February 15th, 2011 at 8:00 PM

Vol. 56, No. 2, February, 2011

I�d like to start off by thanking veteran DAS memberJack Fisher for his January feature presentation �The Sun.�Jack did a great job bringing interesting facts about the sunto light. For February�s main meeting we have two mini-talksby DAS members: NASA Solar Missions, by Bill McKibben,and the Greenwich Observatory, by Jim Barkley.

It�s my sad duty to report that in late January, DASmember and Delmarva Stargazer Dave Short, who was alsoan AP SIG member, died suddenly at his home. Dave hadan upbeat attitude and an enthusiasm for astrophotographyand he was an energetic and positive member of the AP SIGin recent years. Dave remarked several times that just oneparticular meeting of the AP-SIG was worth the price ofadmission to the DAS for a year. Although he didn�t look it,Dave was born and grew up on �the big Island� of Hawaii.You may remember the joint presentation Dave gave with BillMcKibben at last October�s DAS meeting describing theirrecent visits to the observatories on Mauna Kea. Dave issurvived by his second wife, Jeanne Haley, of Landenberg,PA. He will be missed.

A club works best when all of its able-bodiedmembers pitch in and help out in whatever way they can. Ifyou would like to talk about how you can contribute to theDAS, call me at 302-239-0949. I�m sure we can come upwith something that you can do to help the DAS that suitsyour interests.

We have a particular need for MSP supervisors for2011 and we have an opening for one more mini-talk in Juneto fill out our Main Meeting schedule. There are also sometelescope refurbishing projects in need of help. As always, agood idea of your own is always welcome, provided it doesn�tcost a lot and you�re willing to lead the charge!

DAS Member Star Parties ! Bill Hanagan

The late January and early February MSP dateswere all �NO-GOs� due to the snow and freezing rain thatwe�ve experienced this winter.

The potential dates for the next MSP cycle areFebruary 25 and 26 and March 4 and 5. This is the first oftwo possible MSP cycles which includes dates we might usefor the Spring Messier Half-Marathon. As in the past, theHalf-Marathon is planned for Gus�s Elk River property southof Elkton. However, if ground conditions aren�t favorable we�llprobably delay the Half-Marathon until the following MSPcycle, whose dates are March 25 and 26 and April 1 and 2.If that happens, we may schedule a regular MSP at the Sawin.

NOTES ON THE MEMBER STAR PARTIES (MSPS)For each MSP cycle there are usually four potential

dates designated in advance, but which of these is used forthe event is �flex-scheduled� according to the weather usingthe DAS Yahoo Group email system.

Please be sure to mark your calendars with thepotential MSP dates that appear above! Obviously, youneed to keep as many of these dates open as possible sowhen a GO announcement is made you�re in a position toattend the DAS Member Star Party regardless of which datethe weather favors!

Finally, I�d like to remind you that you need to besigned up for the DAS Yahoo Group to receive the schedulingannouncements for and directions to the MSPs. A full descriptionof the MSP program appears on the DAS website at http://delastro.org and in the December 2009 issue of the FOCUS.

Each issue of FOCUS is full of useful hyperlinks. Just click onany graphic or telltale blue web address and your browser shouldtake you to additional linked web resources.

See the Chart on Pages 8 & 9 for a complete listing of MSP�s for 2011

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�PUBLIC NIGHTS� at the Mt. CUBA OBSERVATORY...

The Mt. CubaObservatory PublicNights continue yearround! In addition tolearning about manyaspects of the heavens,you�ll have a chance to

MCAO PUBLIC NIGHTS ! Greg Weaver

visit and view our all-digital full-dome planetarium. You canpick up a schedule when you next come to a meeting or getthe latest updated version off the website at: http://MountCuba.org. Programs are presented on Mondaynights at 8pm. Please check the website for programsplanned, full details and updates.

The schedule for 2011 follows:

February 15: Two Mini-Talks: 1) NASA Solar Missionsby Bill McKibben, and 2) The Greenwich Observatory byJim Barkley

March 15: Two Mini-Talks: 1) Auroras by Rob Lancasterand 2) DAS Loaner Scopes by Tom Sidowski,

DAS Main Meeting Topics and Speakers for 2011April 19: Two Mini-Talks: 1) Selecting a Secondary Mirrorfor Your Newtonian Telescope by Bill Hanagan and2) Deep Sky Quasars, Super-Novas, and Related Phenom-ena by Bill McKibben

May 17: Dinner Meeting: Open

June 21: Mini-talks: 1) Eyepieces Inside and Out by DaveSewell and Terry Lisansky and 2) Scheduling Next Year�sTalks, by Bill Hanagan

Regular Features: Greg Lee will once again give us aregular briefing on �What�s Up in the Sky.�

7:00 p.m., Tuesday, February 15, 2011 In the Library at the Mt. Cuba Observatory

In addition to routine items of business such as theTreasurer�s report, we�ll be discussing the following items:

The PRESIDENT�S DAS BOARD MEETING AGENDA1) Plans for the May Dinner Meeting2) Upcoming elections for board member at large.

Three positions are up for election.3) The DAS short course on astronomy.

As always, DAS board meetings are open to all DAS members.

Feb 28 Jack Fisher �Origins of the Sun�Mar 14 Sheila Vincent �TBD�Mar 28 Harry Shipman �TBD�Apr 4 Lynn King �TBD�May 2 Greg Lee �TBD�May 16 Greg Weaver �Light Pollution�Jun 6 Judi Provencal �TBD�Jun 20 Don Wilson �TBD�

Date Speaker Topic

RARE TELEVUE 20/20 SALE ! Bill HanaganIn honor of the NorthEast Astronomy Forum�s 20th anniversary, TeleVue is offering

20% off on all Eyepieces, Parracorrs, Powermates and Barlows through participatingvendors from February 4 to April 17, 2011. One nearby vendor, �Skies Unlimited�, has

announced that it is participating in this sale and other vendors of astronomy gear are likely to participate as well. It�s a littleunusual for Televue to offer a discount on their eyepieces, which many people consider to be the finest made. This appearsto be a rare opportunity to get top quality gear at a very significant discount. Don�t expect to see this again anytime soon.

NEW

NEW

Dumbell Nebula - Messier 27, Planetary Nebula(NGC 6853), in VulpeculaCredit: Photo by DAS Member Rick Davis.

Observing with the Delaware Astronomical Society...

The DAS astrophotography special interest group (DASAP SIG) meets on Friday nights at 7:30pm every other month at Mt.Cuba regardless of weather. The SIG also meets for photo shootsscheduled on 1-2 day notice to synchronize with the weather.

The monthly meetings are informal and typicallyinclude the presentation of astrophotos taken by the membersalong with an extended question and answer period. Objectscommonly photographed include constellations, auroras, lunareclipses, and planetary photos, as well as a wide variety of deep-sky objects such as nebulae, galaxies, star clusters, etc. Thetopics discussed cover the entire gamut of astrophotography,from how to get started with a minimum of equipment, to polaraligning your telescope, all of the way to the fine points of usingauto-guiders and post-processing digital images.

You can get started in astrophotography with justyour current camera mounted on a tripod or a motorizedtelescope by taking wide field photographs of meteor showers,conjunctions, constellations, and star trails. As you move toprogressively fainter and smaller subjects, you�ll need betterequipment. Joining the AP SIG is a great way to learn whatequipment you�ll need and what works well before you spendyour money. If you are interested in joining the AP SIG, justemail your name, address, and phone number to me athanaganw?comcast?net (using �@� and �.� in place of ? and ?).

The DAS Amateur Telescope Making (ATM) SpecialInterest Group (SIG ) meets on evenings and weekendsaccording to the availability of the members and the particu-lar projects that are underway. Currently the ATM SIG has amedium Dob building program under way. The general rangeof activities of the ATM SIG includes all manner of telescopemaking, mirror making, and the making of accessories for

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DAS Special Interest Groups for Photography and Telescope Construction...DAS ASTROPHOTOGRAPHYSPECIAL INTEREST GROUP ! Bill Hanagan

DAS AMATEUR TELESCOPE MAKING SPECIAL INTEREST GROUP ! Bill Hanagan

telescopes and observing.Anyone interested in joining the ATM SIG should

email their name, address, and phone number to me athanaganw?comcast?net (using �@� and �.� in place of ? and?). Meeting dates are announced primarily by email, so ifyou are interested in telescope making, be sure to letme know!

The DAS also maintains a club observatory on thegrounds of the Mt. Cuba Astronomical Observatory. TheSawin Observatory houses the club�s permanently mounted12.5" reflecting telescope and a 17.5" Coulter Odyssey 2Dobsonian telescope. They are for the use of club membersonce they are trained and checked-out in a simple operatingprocedure. Members who are interested in becoming keyholders of the Sawin Observatory should contact me at 239-1844 to arrange for training in the use of the facility.

One of the best advantages of being a member ofthe Delaware Astronomical Society is that all members havethe privilege of being trained to use and then borrow equip-ment owned by the club for personal use. Currently, wehave two scopes available for loan: a Celestron 8" Schmidt-Cassegrain, and a 6" Orion Sky-Quest XT6 Dobsonianreflector. The loan is for at least a month. If you�re interestedin checking out either of these scopes, contact Tom Sidowskiat 239-1844.

LOANER TELESCOPES and SAWIN OBSERVATORY REMINDER !Tom Sidowski

As always, please consider submitting one or moreof your favorite astrophotos for publication in the FOCUS. Arecent photo is not required. You can email your photo(s) as.jpg files to our FOCUS editor, Joe Neuberger at his addressat jrneuberger@gmail.com. Please include a text file brieflydescribing how you made each photo (in Microsoft Wordformat) along with any by-lines or captions you would like Joeto use. If you would like, you can write a more in-depthdiscussion to go with your photos. Joe can make a master-ful layout, but if you would like to suggest a layout of yourown you can insert copies of your photos into the Worddocument to give him an idea what you would like to see.Either way, don�t forget to attach a high resolution .jpg file toyour email for each photo. Joe has done a great job improv-ing the look of the FOCUS and adding relevant links to takeadvantage of the fact that the FOCUS is now on-line, but likeall newsletter editors, he needs as much material as he canget from club members.

NEW The next AP SIG meeting is flex-scheduled for eitherFriday, February 18 or Saturday February 19 at 7:30 P.M. atMount Cuba. As usual, the specific date of the meeting willbe announced via email to the AP-SIG group members andvia the DAS Yahoo group email list.

The special topic for the meeting will be matchingdetector pixel size with telescope focal length for deepsky photography.

.

The Pleiades -Credit: Photo by DAS Member Rob Lancaster

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NEW

DAS FORUM / E-MAIL SITE ON YAHOO ! Don Shedrick

This is a restricted e-mail service for use byDAS members for DAS purposes. To use this site,go to http://groups.yahoo.com; search for DelawareAstronomical Society; and click on the link that comesup. To join, you must have a Yahoo ID and password;if you don�t, you can register at this time by followingYahoo�s instructions. You will then be allowed to �Jointhe group� upon clicking in that box. You must thenregister for the DAS group and add your profile byclicking on �add new profile� and completing the form.

When adding or editing your profile, you will needto enter your actual name in the �Real Name� box so youcan be identified as a DAS member so Don Shedrickcan approve your application to join the DAS group, andeveryone will know to whom they are communicating.

Finally, specify your desired email address fordelivery of messages. Note: you may choose to nothave your name and email address displayed to anyoneother than DAS members who are members of theYahoo DAS email group.

For more detailed instructions, go to the DASwebsite under DAS Resource Links.

LIBRARY NEWS ! Glenn Bentley

MAGAZINE SUBSCRIPTIONS ! Bill McKibbonSKY & TELESCOPE will be processed by the

club for the first subscription year only. The publishershould then send renewal notices directly to thesubscriber at the club rate of $32.95. The subscribercan then pay the publisher directly.

NOTE: If you receive a renewal notice for anamount other than $32.95, check to see if there areany special offers included in the rate. Also check therenewal date printed on the magazine address label.These �special offers� are likely to occur severalmonths prior to the renewal date. However, if you areapproaching your renewal date and have not receivedthe correct renewal notice, contact me and I willprocess the renewal through the club.

ASTRONOMY will continue to be processedby the club for all subscription years.

Please see the renewal form at the end of theFOCUS for additional renewal information.

MEMBERSHIP EXPIRATION NOTICES! Bill McKibben

If you receive the FOCUS by email, you will benotified of your membership renewal by email. If youreceive the FOCUS in the mail and the mailing labelon the envelope containing your FOCUS is markedwith red marker, your membership is expiring or hasexpired. Please see the renewal form at the end ofthe FOCUS for additional renewal information. Alsosee the �Magazine Subscriptions� section in theFOCUS for information about subscription renewal.

For all those now using the Mt. Cuba LendingLibrary a hardy thanks. Please remember that thelending period is two months. If you�d like to keep thebook longer, please re-sign the log sheet.

MT. CUBA LENDING LIBRARY ! Paul Stratton

I invite the membership to drop by the DASlibrary after the February meeting to scan for titlesproviding stimulating cloudy night reading. The librarywould also like to thank the many members whodonated books to the library over the year just con-cluded. Thank you all very much.

ASTRONOMICAL LEAGUE MEMBERSHIPDAS members have the opportunity to become

members in the Astronomical League at the dis-counted rate of $7.50 per year. Benefits include theReflector (a quarterly newsletter), observing programs,awards, discounts on books and educational materi-als. For questions on joining the Astronomical League,contact Lynn King at meetings, call 302-764-8816 oremail KLynnKing@verizon.net.

NEW

FOCUS uses plenty of photosin banners & elsewhere each issue, and

we want to use YOURS...not Hubble�s!!Please forward photos to the FOCUS editorJoe Neuberger at JRNeuberger@gmail.com

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Catching the LightDigital Astrophotography by Jerry Lodriguss (click for website)

http://shadowandsubstance.com/

http://www.rocklandastronomy.com/NEAF/index.html

ASTRO-PHOTO of the

MONTH

WEBSITE of the

MONTH

NEAFNorthEast Astronomy Forum

The 20th Anniversary of America�s Premier Astronomy Expo!April 16th - 17th, 2011Only 30 minutes away from New York City at Rockland Community College, Suffern, NY

Exciting Two-Day Event Featuring:World-renowned speakers; Astronomy workshops;Daily solar observing; STARLAB planetarium shows;Getting Started classes for beginners; Space & Astronomy events for kids.

More than 130 on-site Vendors with fantastic door prizes!

This image is acomposite of severaldifferent images shot

with different focallengths.

The main backgroundfield was shot with a

Nikon 85mm f/1.4 lensworking at f/5.6 on a

modified Canon1000D (Digital Rebel

XS). Longer expo-sures of Simeis 147,

M35 and NGC 2158,and the IC443 region

were combined withthe wide-field to

increase the depth ofdeep-sky objects in

the image.The Moon was shotwith a telescope with

1040mm of focal length at f/8. Click the photo above to be taken to the interactive web version.

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Old ATM Mirror Complete at Last !!!!! Bill Hanagan

Many Amateur Telescope Makers (ATMs), includingyours truly, got interested in the hobby during their schoolyears when they discovered that they could not only buildtheir own Newtonian telescope, they could also grind, polish,figure, and even silver the primary mirror themselves! Formany students who were interested in owning their owntelescope, making their own mirror seemed like a greatopportunity to get around a severe shortage of funds as wellas an introduction to an interesting hobby.

The young Rich LeMay got started in mirror makingback in 1964 by grinding and polishing a 6� f/5.3 Newtonianprimary mirror using supplies and instructions from EdmundScientific. Rich successfully ground his mirror and polishedout the pits left by fine grinding, but he stopped short offiguring the mirror to the parabolic surface of revolutionrequired for a Newtonian telescope to perform well.

Without an expert to guide them, first time mirrormakers who work alone often find the literature on mirrortesting and figuring to be confusing and difficult to follow, sotheir mirror project stalls at the figuring stage. Anyone withthe inclination to try mirror making is almost certain to haveother interesting projects to work on if they run into troubleon their mirror project. And, in some cases, life simplyintervenes and puts an ATM project on hold regardless of anindividual�s level of commitment. The end result is that quitea few mirror makers, especially those working alone, nevercomplete their mirror. Decades go by until they either passaway and the unfinished mirror gets disposed of poorly byrelatives, or the mirror gets sold. In Rich�s case, though, thestory has some unusual plot twists.

In the early 1970�s, Rich was teaching an AdvancedPlacement course in high school chemistry and decided tosilver his mirror as a chemistry demonstration. Rich reportsthat the silvering process was very successful and that thecoating lasted much longer than the 6 months often quotedin the literature. If you store a silver coated mirror away in aprotective environment, the coating can actually last foryears. Regular exposure to airborne contaminants, espe-cially sulfur, is what gives a silver coating a short service life.

Of course, having silvered the mirror, Rich had tosee if the mirror worked, so he set it up in a temporaryarrangement aimed at the moon. Although Rich reports thathis view of the moon was sharp, he knew he had not testedand figured the mirror to completion and he did not mounthis mirror in a permanent telescope.

For the last 10 years or so, I�ve urged Rich on andoff to finish his 6� mirror and get it into a telescope. SinceRich has been a good friend over the years, I�ve offered tohelp, but Rich has declined. I�ve also recommended he takehis mirror to the Delmarva Stargazer�s �Mid-Atlantic MirrorMaking Seminar� (MMMS) where I and several other experi-enced mirror makers could help him finish it, but again Richhas declined. I should also note that professional mirrormaker Steve Swayze has helped guide seminar attendees tohigh quality results in every year the seminar has been held.

Over the years, I�ve spoken at DAS meetings and

Delmarva Stargazer Meetings many times about the superiorperformance of well made amateur optics when compared tomass market telescopes. However, I doubt that very manypeople fully appreciate the improvement over mass markettelescopes that amateur optics can achieve. In any case,the magnitude of the difference between mass-market andwell made optics never quite hit home for Rich until he got apractical, first-hand demonstration.

At the October 2010 Delmarva �No-Frills� Stargaze,Rich and several others in our club toured the observing field.At the far end of the field, we happened upon Ralph Gruenand his 8� Newtonian. I helped Ralph make his 8� mirror atthe MMMS in the spring of 2010 and he was eager to showme how it turned out. So, Ralph gave us a tour of about adozen familiar Messier objects through his telescope, mostof which we had just seen through a number of commercialtelescopes. Ralph�s ATM 8� telescope proved to be anoutstanding performer and the group came away deeplyimpressed with the amazing views that could be had usingamateur made optics. Afterward, Rich said �I really want tofinish my 6 inch mirror.� He repeated that a few more timesthat night and the next morning, so I once again offered tohelp him finish his 6� mirror�and this time he took me up onmy offer. A quick laser test showed that Rich had polishedhis mirror long enough to remove the pits and fissures leftbehind by fine grinding, so we could proceed with figuring, amajor step in mirror making that Rich had never gottenaround to. But what was the geometric shape of the mirrorsurface, known as the �figure,� like? To assess the figure of Rich�s mirror before startingto work on it, I set the mirror on the test stand and appliedthe Ronchi test using a 133 cycle/inch Ronchi gratingpositioned outside of the mirror�s radius of curvature (ROC).The photo of that test appears below. While the image mightappear to suffer from thermal currents, there were none. Thedeviations seen in the photograph below represent actualerrors on the mirror surface. (continued on next page)

(Continued on next page)

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Old ATM Mirror(Continued from preceeding page)

When the grating is positioned outside of the ROCin the Ronchi test, a parabolic mirror will show bands thatturn outward as you move from the center to the edge of themirror. A sphere will show straight lines from top to bottom.On Rich�s mirror, the bands turned inward, revealing an oblatespheroid. The mirror curvature was changing from center toedge, but in the opposite direction from that required. Ofcourse, the curvature can�t just be in the right direction, youmust also get exactly the right amount of curvature.

The fact that the mirror was oblate meant we hadsome work to do, but in itself this is not a serious defect, itsimply takes time to work out. Unfortunately, the mirror hada much more serious defect: it was not a consistent surfaceof rotation and showed significant signs of astigmatism.This is revealed by the asymmetry of the bands to the leftand right of center.

The small silver lining in the starting condition of themirror was the absence of any significant turned down edge(TDE). The fragile extreme edge of the mirror behaved as if ithad been hit hard in a few places, but the extreme edge isn�tvery relevant because it covers no area. For a TDE problemto be significant, it must affect a zone having a measurablewidth, not just a few microns of glass where the mirrorsurface meets the bevel.

I won�t go into a detailed explanation of how Rich�smirror was transformed into a high quality paraboloid be-cause it would take too long. However, it�s worth brieflymentioning the optical tests employed: the Ronchi test wasused to follow our efforts to make the mirror surface symmet-ric again and to push the mirror surface through a sphereand part of the way to a paraboloid, then the Ross nullversion of the Ronchi test was used to make further refine-ments. We also used the null Foucault test to touch upsome of the residual asymmetry. Near the end, we switchedto the more sensitive but slower zonal Foucault test to finetune the correction of the mirror. Along the way, we also

The results from the final zonal Foucault test of themirror appear in the screen copy below. The calculated P-Verror was about 1/16 of a wave on the wavefront and theestimated Strehl Ratio was 0.987. These are very favorableresults. However, it should be kept in mind that the zonalFoucault test can give results that are optimistic, particularlyif correction does not proceed smoothly from the center tothe edge of the mirror. For this mirror, though, the progres-sion of correction is reasonably smooth from center to edgeas can be seen from the final Ronchi images. It should alsobe kept in mind that the value of the Strehl ratio obtainedfrom this test is substantially less reliable than a Strehl ratioobtained from an interferometric test, largely because a largepercentage of the mirror�s surface is not sampled during thezonal Foucault test and the number of samples obtained isquite small.

used the Couder test and the halo balancing test to evaluatethe condition of the mirror�s edge.

The photo on the left, below, shows the Ronchi testof the finished mirror with the grating positioned outside ofthe ROC. The right hand photo was taken at the same timebut with the grating positioned inside the ROC. Diffractioneffects in the left hand photo could give a beginner the falseimpression of TDE. However, the right hand photo showsthat there is no significant TDE problem. The Couder testconfirms this.

Keeping the optimistic tenden-cies of the zonal Foucault test in mind,I should note that I�ve tested quite a fewcommercial telescope mirrors using thezonal Foucault test. Many commercialtelescope mirrors have shown ½ to 1wave or more of correction errors andzonal errors, often in addition to aserious turned down edge. So, whilethe wavefront error and Strehl ratio forRich�s mirror may be somewhat lessoptimistic than the zonal Foucault testsuggests, I am confident that Rich�smirror is now in the elite company ofamateur made mirrors that stand headand shoulders above those used incommercial mass-market telescopes.

Congratulations Rich, your mirrorfinally made it to the finish line! I haveone more recommendation to make: getthe mirror coated and into a telescope!

(continued on next page)

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2011 MSP Potential Dates - Print, Clip, & Hang in a Prominant Place! - Then JOIN US!

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1. 2. 3.

2011 MSP Potential Dates (continued from preceeding page)

Watch Out for Solar Sail FlaresFebruary 1, 2011: It�s a calm and peaceful night. Starstwinkle in the velvety darkness overhead as a distant planeblinks silently on the horizon. You could almost hear a pin drop.

High overhead, out of the darkness, a bright

A camera in Finland caught NanoSail-Dflaring on Jan. 30th. The streak of light wasalmost three times brighter than a 1st-magnitude star.Credit: Esko Lyytinen.

light surges intoview. For 5 to 10seconds itoutshines thebrightest stars inthe sky, mimick-ing a supernova,perhaps evencasting faintshadows at yourfeet. The silenceis broken byyour own excitedshouts. Could thishappen to you?

�It could, if you happen to be outside whenNanoSail-D flies by,� says Dean Alhorn of the MarshallSpace Flight Center in Huntsville, AL. �We think the space-craft could produce this kind of display from time to timewhen sunlight glints off the reflective fabric of its solar sail.�

On Jan. 21st, NanoSail-D unfurled a 10 m2 sail 650km above Earth�s surface, becoming the first solar sail toorbit our planet. For the next few months it will skim the topof the atmosphere, slowly descending in a test of �dragsails� as a means of de-orbiting space junk. If all goes asplanned, the spacecraft will disintegrate like a meteor inApril or May of 2011, dispersing harmlessly more than 100km high.

Meanwhile, sky watchers should be alert for flares.

Many people have already seen Iridium flares�brilliant flashes of sunlight glinting off the flat antennas ofIridium communication satellites. Some Iridium flares are sobright, they can be seen in broad daylight. NanoSail-D couldbe even brighter.

�The surface area of our sail is six times greater thanthat of a single Iridium antenna,� points out Alhorn. �Plus,we�re closer to Earth. It all adds up to a much brighter flash.�

As NanoSail-D gets closer to Earth, it could theoreti-cally produce flashes of light 10 to 100 times (2.5 to 5astronomical magnitudes) brighter than the planet Venus.That�s the sort of thing you can see even through city lights.

In between flares, however, the sail is fairly dim.Internationally-recognized satellite tracking expert TedMolczan describes what he and others have been seeing:

�NanoSail-D can be a challenging object to spot, butby no means impossible. At its faintest, it has been invisibleeven in large binoculars, but at its brightest, it has been seeneasily with the un-aided eye. The great variation in brightnessis due to its shape; it is a large, thin sheet of highly reflectivematerial. Seen edge-on, it is faint, but seen face-on at afavorable sun-angle, it may rival the brightest stars.�

NanoSail-D flyby predictions may be found in severalplaces on the web: Heavens-Above, Spaceweather.com, andCalsky among others. These sites will tell you when the sailwill soar overhead�but not when it will flare. The orientationof the sail isn�t known precisely enough for that.

�Because it is impossible to predict exactly whenNanoSail-D will be bright, observers can increase theirchance of success by watching over a period of severalminutes,� says Molczan. �A plot of its predicted path on astar chart, with annotations of the time at intervals of oneminute or so, will help the observer stay focused on thesatellite�s approximate position as it moves across the sky.

(contintued on Page 11)

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February 6, 2011: It�s official: The sun is a sphere.On Feb. 6th, NASA�s twin STEREO probes

moved into position on opposite sides of the sun,and they are now beaming back uninterruptedimages of the entire star�front and back.

NASA released a �first light� 3D movie on,naturally, Super Bowl Sunday: click above to access.

�This is a big moment in solar physics,� saysAngelos Vourlidas, a member of the STEREO scienceteam at the Naval Research Lab in Washington, DC.�STEREO has revealed the sun as it really is�asphere of hot plasma and intricately woven magneticfields.�

Each STEREO probe photographs half of thestar and beams the images to Earth. Researcherscombine the two views to create a sphere. Thesearen�t just regular pictures, however. STEREO�stelescopes are tuned to four wavelengths of ex-treme ultraviolet radiation selected to trace keyaspects of solar activity such as flares, tsunamisand magnetic filaments. Nothing escapes theirattention.

�With data like these, we can fly around thesun to see what�s happening over the horizon�without ever leaving our desks,� says STEREOprogram scientist Lika Guhathakurta at NASA head-quarters. �This could lead to significant advances insolar physics and space weather forecasting.�

Consider the following: In the past, an activesunspot could emerge on the far side of the suncompletely hidden from Earth. Then, the sun�s

rotation could turn that region toward our planet,spitting flares and clouds of plasma, with little warning.

�For the first time ever, we can watch solaractivity in its full 3-dimensional glory,� says Vourlidas.

�Not anymore,� says Bill Murtagh, a seniorforecaster at NOAA�s Space Weather PredictionCenter in Boulder, Colorado. �Farside active regionscan no longer take us by surprise. Thanks to STEREO,we know they�re coming.�

NOAA is already using 3D STEREO models ofCMEs (billion-ton clouds of plasma ejected by thesun) to improve space weather forecasts for airlines,power companies, satellite operators, and othercustomers. The full sun view should improve thoseforecasts even more.

The forecasting benefits aren�t limited to Earth.�With this nice global model, we can now track solarstorms heading toward other planets, too,� pointsout Guhathakurta. �This is important for NASAmissions to Mercury, Mars, asteroids � you name it.�

NASA has been building toward this momentsince Oct. 2006 when the STEREO probes left Earth,split up, and headed for positions on opposite sidesof the sun. Feb. 6, 2011, was the date of �opposi-tion��i.e., when STEREO-A and -B were 180 de-grees apart, each looking down on a different hemi-sphere. NASA�s Earth-orbiting Solar Dynamics Obser-vatory is also monitoring the sun 24/7. Workingtogether, the STEREO-SDO fleet should be able toimage the entire globe for the next 8 years.

The new view could reveal connectionspreviously overlooked. For instance, researchershave long suspected that solar activity can �goglobal,� with eruptions on opposite sides of the suntriggering and feeding off of one another. Now theycan actually study the phenomenon. The GreatEruption of August 2010 engulfed about 2/3rd of thestellar surface with dozens of mutually interactingflares, shock waves, and reverberating filaments.Much of the action was hidden from Earth, butplainly visible to the STEREO-SDO fleet.

�There are many fundamental puzzles under-lying solar activity,� says Vourlidas. �By monitoringthe whole sun, we can find the missing pieces.�

Researchers say these first-look images arejust a hint of what�s to come. Movies with higherresolution and more action will be released in theweeks ahead as more data are processed. Stay tuned!

(Continued on next page) Author: Dr. Tony Phillips | Credit: Science@NASA

More Information: Download a self-guided Science Briefingexplaining this historic �First.� Solar Terrestrial Relations Observatory �STEREO home page Solar Dynamics Observatory � SDO home page

First Ever STEREO Images of the Entire Sun

The solar sphere as observed by STEREO and the Solar DynamicsObservatory on January 31, 2011. Because the STEREO separation wasstill slightly less than 180o at that time, a narrow gap on the far side of theSun has been interpolated to simulate the full 360o view. The gap andquality of farside imaging will improve even more in the days and weeksahead. Click for the webpage and the movie file of a 360 degree Sun!

-11-

BONUS: To encourage amateur astronomers tomonitor the sail, NASA and Spaceweather.com have joinedforces to stage a photo contest. Cash prizes ranging from$100 to $500 are being offered for best images of NanoSail-Dsubmitted between now and the time the sail disintegrates.High-resolution telescopic images of the spacecraft, wide-angle shots of NanoSail-D soaring overhead, and lucky-shotsof flares are all eligible. Visit nanosail.org for complete details.

Author: Dr. Tony Phillips | Credit: Science@NASA

More Information:NanoSail-D � home pageSolar Sail Stunner � Science@NASANanoSail-D tracking sites:Heavens Above,Spaceweather.com, CalskyNanoSail-D Photo ContestA Brief History of Solar Sails � Science@NASA

Observe with the unaided eye, or binoculars with a wide fieldof view, like 7x50s.�

The brightest flares are likely to occur when thespacecraft is near the horizon. Former NanoSail-Dprincipal investigator Mark Whorton (previously atNASA, now at Teledyne) explains why:

�Early in the mission NanoSail-D will be tumbling, soit really doesn�t matter where it is in the sky. Flashes mightoccur almost anywhere along its path. But later in themission it will be aerodynamically stabilized: the flat surfaceof the sail will face forward, much like the sail on a terrestrialsailing ship. That means you will see it edge on (dim) when itis directly overhead and face on (bright) when it is closer tothe horizon.�

So check the predictions, go outside and take a look.Says Alhorn, �You might see something worth shouting about.�

Watch Out for Solar Sail Flares (Continued from page 9)

Observing solar stormsfrom two points of viewhas allowed forecastersto made 3D models ofadvancing coronal massejections (CMEs),improving predictions ofEarth impacts. Click atright for the web animationCredit: NOAA/SWPC

Above, an artist�s conceptof STEREO surroundingthe sun.

First Ever STEREO Images (Continued from preceeding page)

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