Summer 2008 Newsletter
Click here for a PDF version of this newsletter best for printing.
Diane Colvin, BPAA Events Manager Okay, now I’m really whining. In the summer 2007 issue of the Newsletter I said, “Surely this has been one of the worst fall/winter seasons on record for viewing the night sky.” Little did I know that this fall/winter would be even worse. We are fortunate to have the benefit of at least recalling the beauty of the night sky through the planetarium shows. All the volunteers involved in the planetarium presentations deserve much credit for their good work and for keeping our hopes alive. We do have the regional star parties to look forward to, where the odds of enjoying clear skies are higher. The opener this year is in early June. The First Light Star Party, sponsored by the Northwest Region of the Astroleague, will be held June 5 – 7 at Skyview Acres, about 10 miles northeast of Goldendale. The organizers rightfully claim that the site is darker than Table Mountain, but admit it’s not as dark as the Oregon Star Party (OSP). First Light is followed by the Shingletown Star Party, in Northern California, near the entrance to Mt. Lassen Volcanic Park. The dates are June 30 to July 7. We’ve heard good reports about this star party from participants at other star parties. The Table Mountain Star Party is scheduled for July 31 through August 2, followed closely by the Mt. Bachelor Star Party, August 6 – 10. Diehards will want to go directly from one to the other for approximately ten days of viewing in dark skies. The Oregon Star Party, the premier event, is in late August, and includes the Labor Day weekend. Activities and speakers are scheduled for August 28 through the 30th, but the site will be open for viewing from August 25 through the 31st. For more information on all of these star parties, check out the websites listed above in the Calendar. Upcoming sky highlights include some nice pairings of the Moon and the planets. On June 7, the crescent Moon is 2 degrees below Mars. On the next evening the Moon will form a triangle with Regulus and Saturn. On June 19 the Moon is beside Jupiter, then below Jupiter on June 27. On July 17 and August 13, the Moon is again near Jupiter. The Perseid meteor showers, which peak on August 12, are usually impressive, but might disappoint this year as they will be washed out by a gibbous Moon at peak time. The summer solstice is June 20, maybe. Some insist June 21 is the correct date. The June issue of Sky and Telescope at page 55 has an interesting blurb on the issue, which hinges on the kind of universal time used. Ephemeris Time (ET) is based on the orbits of the planets around the Sun, and can be predicted accurately for many millennia. Coordinated Universal Time (UTC), which tracks Earth’s daily rotation, varies because changes in the weather and the ocean currents shift Earth’s mass slightly. It is thus necessary to add a leap second to the UTC every year or so. This year, the solstice happens 27 seconds into June 21 under ET, but under UT the solstice occurs at 23:59 on June 20. Just to be safe, I plan to wear my Druid costume and keep the bonfires going both days. Note that in June, July and August the planetarium shows and the beginner sessions for our local star parties will begin at 8:00 p.m. And remember that any member at any time who is planning to observe can invite others to join in by sending an email to bpaa@yahoogroups.com. To join our email group, send an email with your name to bpaa-owner@yahoogroups.com and we can enroll you. If you want to also have web access to the messages and files, you can join the Yahoogroups by clicking the register link for new users on http://groups.yahoo.com/, and requesting to join our group at http://groups.yahoo.com/group/bpaa/. The system will send us a message, and we’ll approve your request after we verify your membership. Star Parties are on the way: the local favorites, Table Mountain, Oregon Star Party, and Mt. Bachelor, are discussed in the Calendar Notes. Remember that Table Mountain has a limit on the number allowed to attend so sign up early if you really are looking forward to attending. Our past two member’s meetings have been interesting and well attended. In April BPAA’s Chief Astronomer Malcolm Saunders led a discussion on possible upgrades to the Ritchie telescope’s declination drive mechanism. To improve the telescope’s pointing accuracy we need either a new Byers worm wheel or a cable drive. The consensus seemed to be that a cable drive would be the most cost-effective mechanism to improve pointing accuracy. At May’s member meeting Dr. David Kirscher, a local optometric physician, gave a detailed description of night vision and dark adaptation. Dark adaptation is both a skill and a capability that visual observers must master if they wish to pursue faint celestial objects. Preparation during the day before a night of observing is critical. Rest, proper nutrition, no alcohol, and hydration are all important. Shielding the dominant eye from bright sunlight by wearing a black patch over one eye or by using red-tinted goggles also helps. During the night all possible steps should be taken to avoid white light in the dominant viewing eye. Keeping the eye covered with a black patch except when viewing through the eye piece will prevent accidental exposure to white light. Fund-raising activities to support the BPAA’s Capital Project Initiative are underway. A series of meetings and site visits have been held with major funding organizations. Reports from these meetings have been positive and we have learned much about the funding process. We have also had several meetings with the Bainbridge Island Park and Recreation Department staff and the Park Board members to brief them on our Capital Project Initiative. We will again have a booth, run planetarium shows, and join the parade for the Island’s Fourth of July festivities. Volunteering for this event is an excellent way to meet active club members. There’s a place for all ages, skills, and talents, from schmoozing in the booth to carrying a sign in the parade. Call 206-842-9152 (the BPAA information line) if you’re interested in joining the fun. In May, I will be attending the Society for Astronomical Science’s annual conference at Big Bear Lake, California. This year’s conference will emphasize remote observatory control, a topic most pertinent to BPAA’s plans for a remote observatory. Many astronomers consider the industry standard for “off the shelf” remote telescope and CCD camera control to be ACP and MaxIm control software. Both of these will be used in workshops along with the GSC catalog, PinPoint, FocusMax, and the ASCOM Platform to control various telescope and camera simulators. Frank Schroer, BPAA Treasurer On May 5, BPAA launched a newly designed website. Thanks go to Ben Krokower, our new webmaster, for countless hours spent researching best-in-class content management and membership management solutions, and migration of existing website content over the past several weeks to the new site. Ben brings a wealth of experience as the owner of his own website design company, and we are fortunate to have him as an active member and volunteer. Thanks also to Stephen Ruhl, our outgoing webmaster, for his years of dedication and effort on the BPAA site and for his contributions to the new version. New features include: Look for future enhancements to the website to increase usability, networking and flow of information between members, including additional flexibility in payment processing for membership renewals and donations. We also hope to add blogs and discussion groups. These additions could also enable consolidation of the Yahoo Groups content and capabilities with the BPAA website into a single easy-to-access location, with no additional registration needed beyond that required for membership. We’d love to get your opinions of the new site, and your ideas for improvements! Send any comments or questions to membership@bpastro.org. Chad Ellington The only challenge with (527) Euryanthe on 2008 Jul 26 near 4:47:35 UT +/- 12 seconds will be being one of the lucky ones within the actual path. As you can see from the accompanying figure, there is significant uncertainty in the location of the predicted shadow. (1278) Kenya presents many disadvantages of both shadow uncertainty and timing in terms of nightfall/day-of-theweek which will obviously eliminate most from attempting. Although, a respectable target star with the allure of rare clear skies presents a unique opportunity to contribute significant positional and physical data on this main belt asteroid. Stephen Ruhl I have been using O’Reilly computer books for years. Now they seem be expanding into the amateur astronomy market. O’Reilly’s computer books tend to be references. If you know a subject, you can look up the fine details of a specific syntax or command parameters. You don’t want to go to these books to learn a new subject. The same can be said for Stefan Seip’s book. Even though this book wants to be a primer for Digital Astrophotography (DA), it is not. It is a relatively light effort. There are six chapters: an introduction & conclusion and then a chapter on the Digital Compact Camera, the Webcam, the Digital SLR, and the Astronomical CCD. Each of the meat chapters provides the strengths of each camera system and overview of the equipment and the techniques required to get and process images. Seip gives pros & cons for each style of DA. It provides a good checklist of the different facets of each type, what is required, and how much it costs. He gives real examples with prices that are reasonably current. In some ways this book wants to be a reference book, though it’s not organized as such and it lacks an index. Each camera system can share equipment and techniques with other systems, such as (auto-)guiding, image processing, file formats, etc. Each section may have some words on these topics but you do not get the complete picture and much of the content is repeated. For example, the author spends a couple of paragraphs in the Digital SLR section discussing guiding and then a little over a page on the same topic in the Astronomical CCD chapter expanding on what he has already said. Each of the camera chapters has a section on Image Processing: six pages for Compact Cameras, six pages for Webcams, nine pages for DSLRs, and 12 pages for Astronomical CCDs. The other disconcerting aspect of these discussions is that they are specific to applications and lack any notion of theory. I may be especially critical on this because I am in the midst of reading Berry & Burnell’s Handbook of Astronomical Image Processing. Their book is nearly 700 pages on this one subject with math, and a lot fewer pictures per page. If you are interested in DA, this book could assist you in identifying your interests, get you focused, and provide you a checklist of things to research. But don’t expect to find any definitive answers. After finishing each chapter, I was left with questions. The club’s copy of the book is available in the library at the Ritchie Observatory. If you’ve been to the Ritchie Observatory recently you probably noticed the newest addition The Big Picture, housed in Griffith Park Observatory’s Gunther Depths of Space exhibit hall, After the raw data was collected it was sent to the Caltech Center for Advanced Computing Research where it was processed into a single file. The software performed a sequence of operations, such as removing instrumental artifacts, masking bad regions, assigning coordinates to all objects and measuring their properties for such things as brightness, size and shape so they could later be categorized as quasars, galaxies, stars, asteroids, etc. This was a monumental task and the sheer amount of data required the development of new software to complete the project. Once the initial data set went through the various automated software processes it was then cleaned up by hand, pixel by pixel, using Photoshop. Amazingly, this cleanup was performed by just one person, Leslie Maxfield (BS ’95), who works at the Center for Advanced Computing and just happens to be the wife of S. George Djorgovski, Professor of Astronomy at Caltech and one of the primary organizers for the whole project. Candidates for cleanup included airplane lights too dim to be recognized by the processing software, internal camera reflections that cause halo-like rings around bright objects, and bleed trails. Also, since the final image was the result of 16 overlapping data sets, there were many stars that weren’t properly aligned and appeared to be small cloverleaves instead of points of light. Ms. Maxfield would identify them and the data set would be sent back for further processing. When the data was finally processed into a single image it was reproduced in porcelain, so that it was durable enough to be touched and examined up close. This job went to Windsor Fireform, arguably the finest producer of porcelain signage and imagery in the world, located just 60 miles south of us in Tumwater, Washington. If you’ve read porcelain signs at the White House, the Grand Canyon, and major metropolitan zoos, then you’ve seen their work. They also make up interpretive displays for the National Park Service. But for all of their expertise, they had never fired porcelain in sizes as large as The Big Picture required, and had many obstacles to overcome. For one thing they had to make sure that the black background in each panel was consistent throughout. They also had to make sure the background wasn’t too black. If it was too black then very faint white objects would have disappeared and diffuse objects, such as elliptical galaxies, which have a very bright core and fade to nothing at their edges, would appear unacceptably small. Just to get the right shade of black took over 6 months of experimentation. The actual firing of the panels covered an additional six months. Each panel required seven separate firings in the kiln, each time with added mineral colorings. Combined with the fact that changes in humidity affect the final color of an image, it’s a tribute to their expertise that they managed to match the first panels to the last ones emerging from the kiln. More information on The Big Picture and the process involved in making it can be found at What Does Our Panel Picture? After much research I’m unable to pinpoint exactly what area of the sky our panel represents, but I can get very close. For starters, the back of our panel was marked “A-35.” Since the individual panels in The Big Picture are oriented vertically (three 6’-8” panels stacked on top of each other equal The Big Picture’s 20’ height and 38 of them abreast at 4’ each equals its 152’) I’m assuming they would be labeled as rows ABC, with row A at the top, and abreast as 1-38, counting from the left. On page 10 of the PDF file available through the Caltech website http://bigpicture.caltech.edu/articles/ bigpicture_EandS.pdf there is a very nice picture of the panels being installed and the positions of both M87 and M90 are clearly visible (many thanks to Caltech for the picture’s description!). Since M87 is positioned just to the SW of Markarian’s chain, I am assuming they started the installation in the middle of The Big Picture and that the panel containing M87 is panel number C19. By superimposing a grid using planetarium software, oriented exactly east-west (since we know the data was collected using the drift scan method), I am guessing our panel represents an area approximately 3.8 degrees ESE of the star Beta Leonis, otherwise known as Denebola, in the constellation Leo. So much for where our panel is located in the sky, but can we actually see any of these objects through our amateur telescopes? Well, yes and no. The NGC catalogue of deep sky objects lists nothing anywhere near this area of the sky so it’s highly unlikely we would be able to detect any extended objects even from a dark sky site. However, there are two stars, TCY 871-664-1 at magnitude 10.68 and TCY 871-703-1 at magnitude 11.0 which should be visible from Battle Point Park on a clear night. Christian Blanco Griffith Observatory Russell M. Heglund Vertical sundials are popular throughout Europe on walls of public buildings. They are usually on south-facing walls, but other wall directions are usable, though for fewer hours a day. The dials can be artistic or plain. They can show local time, solar time, and compensate for “daylight savings time.” One local example of a wall dial is on the Physics Building at the University of Washington. It reads both standard and daylight savings time. This dial was designed by Dr. Woody Sullivan of the UW Astronomy Department. If walls don’t face true south, the markings are skewed to compensate. Albert E. Waugh covers this subject in his discussion of “Vertical Declining Dials” in his book Sundials— Their Theory and Construction (Dover Publications, 1973). Another source of information about determining the “wall declination” (how far off true North, South, etc…) can be found in the free software available at www.shadowpro.com. Wall dials can be done on a piece of wood, and nailed to a wall, or be pieces of pottery or wrought iron. The wall dial can be one of the easiest sundials to make. Our Battle Point Observatory has an excellent south- facing wall, just waiting for a dial. Sundials Anna Edmonds We usually count telescopes and radio communications and CCDs as astronomers’ tools. We think of satellites and space travel and planetary probes and gamma ray imaging. These are wonderful, important tools. They give us the breathtaking pictures of nebulae and views of the surface of Mars, and ideas about finding water on Jupiter’s moon, Europa. They make us dream of traveling into outer space ourselves. Before Hubble and the first men on the Moon, and before binoculars and Galileo’s telescope, astronomers had sundials and clocks and mirrors. There are also archaeoastronomical records such as the drawings on the Haleets Rock here on Bainbridge, the marks in the caves in Susanville, California that John Rudolph explored, and monumental ruins like Stonehenge. Accurately measuring the circumference of the Earth and, with that, then some distances in the sky, started with the man who was director of the famous library in Alexandria, Egypt back in about 200 BC. Eratosthenes combined his knowledge of geometry with the fact that the Earth is a sphere in order to calculate the Earth’s circumference. He compared that calculation with his measurements of the Moon and then determined the distance to our nearest neighbor. Having taken the measure of the Earth, people began to think of measuring the sky. Eratosthenes started us on the right track, and for 2,208 years we’ve been improving on his findings. Measurements inevitably involve a comparison: For instance, my son was 21 inches long at birth; that is, he was compared to a line of inches. The line wasn’t my son; it was only a convenient tool, a guideline that people had agreed upon years ago. And this example: a friend recently died at the age of 63. My friend’s age was compared to the number of times the Earth had circled the Sun, but he had nothing to do with causing that circling. We generally take for granted another everyday combination of tools. These include writing equipment of various kinds: stones and chisels, pencils and paper, computers and mice and electricity. These we may not usually consider specific tools for astronomers, but we don’t ignore them. They all are the outcome of meaningful writing; they are one of the ways we try to hold on to the present. Historians suggest that the reason people conceived of writing was because they had become aware of a future without them. They say that in human development people had begun to understand the difference between the past, the present and the future. The past and the present were known quantities; the future was uncertain, except for death. With this understanding of inexorable change came the concept of time. Time and light—these are two tools that people have used long before their most primitive marks on stones. These are the astronomers’ tools that are so overlooked in the lists that it’s hard to think of them as such. Not writing, not mathematics. These two, everpresent, but taken for granted. We agree in science that time is a constant (while we know from experience that the “time” in a dentist’s chair is not the same as the “time” with a loved one). And although we use the tool of time, we would be hard put to define it. Can we say what determines time? Does time have to be linear, or is it human life that limits our awareness of time? And light: without the sunlight or the moonlight, without the light from the stars we wouldn’t be aware of the passing seasons, we wouldn’t see the constellations come and go. We wouldn’t see each other. Without the shadows that the light casts on the ground or with a sundial we wouldn’t have the first markers we could watch and count. Without the appearance of Sirius in the east the Egyptians wouldn’t have known that the Nile was about to bring them the fertile mud from the river’s yearly flooding. It’s these lights that we’ve watched as long as we’ve been watching the sky. Mathematics and writing, light (and our eyes) and time, in addition to sundials and telescopes and space travel—these are a few of the tools that are indispensable for an astronomer. Perhaps you can think of others. Talking about eyes leads me to wonder what else we might discover if we could develop our other senses to the same degree that we’ve depended on our eyes in astronomy. We can see outer space, but we haven’t tried to taste it or smell it. We’ve touched a few rocks from the Moon and from Mars, but we haven’t really tried to listen to space. We know that we can see only a narrow spectrum of the wave lengths of light, but we’ve developed tools with which we can “see” beyond those wave lengths into the wider range of electromagnetic radiation with X-ray and gamma ray technology. Sound waves also have not only the range that we hear, but also the sounds beyond our ears’ reach. What might we “hear” and learn if we could explore the universe with the tools not only of ultra sound, but also those of infra sound? Would we then be able to hear the “music of the spheres”? BATTLE POINT ASTRONOMICAL ASSOCIATION Officers Calendar : June-July-August Calendar Notes In Brief Articles Newsletter Editor Vicki Saunders. BPAA Newsletter is a quarterly publication. Submissions due on the 10th of the month before the quarter begins. Query: newsletter@bpastro.org. Send photos and other graphics as separate files.
JuneJuly
August
Weather! Yes, it has been a real nasty spring with average temperatures at least 5 degrees below normal. Although I have no data, the overcast that prevents us from observing seems to have been more prevalent than in past “springs.” Many Clear Sky Alerts did not pan out. On the positive side all this bad weather just gives the BPAA more justification for installing a remote observatory in Arizona. Remote observatory capability is high on my wish list for the BPAA - right up there with restrooms.
New Improved BPAA Website
The accompanying asteroid occultation and lunar graze predictions are abbreviated versions of what will occur in our skies over the next several months. Also, each event is not without its own advantages The only challenge with (527) Euryanthe on 2008 Jul 26 near 4:47:35 UT +/- 12 seconds will be being one of the lucky ones within the actual path. As you can see from the accompanying figure, there is significant uncertainty in the location of the predicted shadow.
and disadvantages so be aware of your equipment and limitations.
Our most likely asteroid occultation occurs on 2008 Jun 22. As you can see from the figure below, Bainbridge Island is well placed to observe this event. The challenge for this event will be having both a clear sky and horizon to the SSE, as the target star will only be some 14 degrees in altitude. 
155 pages. Published by Rockynook, distributed by O’Reilly Media.
Doug Tanaka
on the wall of the meeting room—a digital image of the sky reproduced in porcelain on a thin metal sheet. The panel—4 feet tall and 6 feet, eight inches wide—is an extra copy from one of the newest installations at the Griffith Park Observatory in Los Angeles, appropriately called The Big Picture, and was generously donated to us by one of our island residents.
(photo on page 1) is the largest photographic image ever produced on porcelain enamel. The image is 20 feet high and 152 feet long, and is made from 114 individual panels, all identical in size to ours. The section of the sky Griffith Park’s Picture covers is 15.2 degrees long and 2.0 degrees high, about equal to the area your index finger would cover when held a foot in front of your eyes. Our individual panel is a little less than 1/100th that size and would be the equivalent of holding a fat grain of rice a foot in front of your eyes. 
Data for the image was collected using the 48-inch Samuel Oschin Telescope at the Mount Palomar Observatory as part of the Palomar-Quest digital sky survey. The camera used to collect the data was built at Yale University and Indiana University and is a mosaic of 112 CCDs (4 rows of 28 CCDs each), which covers the telescope’s full field of view. The Big Picture’s full image required over 200 gigabytes of raw data, taken over the course of 20 nights between 2003 and 2004. This raw data was collected using the 48-inch telescope in scan mode, where the telescope’s position is fixed in relation to the earth, allowing the night sky to drift across the CCD array in a steady stream. This mode is different from that used by most amateurs doing digital imagery, where the camera is motorized and tracks the sky to keep the image immobile in relation to the CCD chips. In scan mode stars, galaxies, asteroids and any other objects drift across the camera’s field of view but rather than giving a smeared image, the information comes as long, continuous image strips, one for each CCD array
The final result is an image that, although stunningly beautiful, is not artwork or the impressions of an artist, but an accurate rendition of a true scientific data set. The image covers approximately 100,000 times more area of the sky than the famous Hubble Deep Field image and contains millions of galaxies, hundreds of thousands of stars, about 1,000 quasars, hundreds of asteroids, and at least one comet. In terms of depth, objects in the image range from a relatively close several light minutes in the case of asteroids, to several light years for stars in our own Milky Way galaxy, and up to 12 billion light years for galaxies and quasars at the edge of our visible universe.
http://bigpicture.caltech.edu/articles/bigpicture_EandS.pdf
http://bigpicture.caltech.edu/made.htm
http://www.griffithobs.org/exhibits/bbigpicture.html
Our single panel covers an area of sky roughly equivalent to a fat grain of rice held about one foot in front of your eyes, but where exactly in the sky would you hold this grain of rice? And if you pointed a telescope in the direction of that grain, would you be able to see any of the brighter objects in the panel?
Griffith Observatory, an icon of Los Angeles, was named after “Colonel” Griffith J Griffith who donated 3015 acres of land for a park and $100,000 for an observatory in his name on top of the Hollywood Hills. One of the first sights at the Observatory is an obelisk dedicated to six of the greatest astronomers of all time: Hipparchus, Copernicus, Galileo, Kepler, Newton, and Herschel. Just to the south of that is a beautiful sundial showing the time of day. As you walk down the front pathway, you’ll notice brass lines inlaid into the cement, each labeled with a different planet’s name. Near to the entrance of the observatory is the Sun itself. Each planet’s orbit is laid out throughout the observatory’s grounds to a scale where one foot is equal to about 20,000,000 miles.
Some of the highlights of the interior are a giant pendulum; set to swing from a bearing in the ceiling in order to show the Earth’s spin—the pendulum’s orientation appears to change as the earth turns.
The West wing (The Hall of the Sky) is dedicated to the sun, with several real-time solar pictures, as well as a solar telescope. The East wing (The Hall of the Eye) focuses on the observatory’s history, as well as the history and science of astronomy in general.
There on display is a replica of Galileo’s telescope, and the center plug from the original 200 inch Palomar Mountain telescope mirror. The lower floor holds the greater display of The Big Picture—a section of it now hangs in the Battle Point Observatory—as well as information stations on all of the planets. It also houses the original planetarium projector, a Zeiss Mark IV Projector.
The Observatory’s second sundial tells not the time, like most sundials, but instead the date. The first of its two parts is a tall metal structure with a hole cut out in a overhanging piece at the top. The second piece sits perpendicular to the first, arcing away and upward. On it are the months of the year, and scribe marks depicting the days within the months. Once the sun shines through the hole at precise local noon (actually closer 1300), it crosses the beam and shines on the date. An added feature is the placement of light sensitive diodes (LSDs) along the center of the beam that are activated when the sun crosses over them. On the facing wall is a diorama of the constellations. When the LSDs activate, the diorama lights up the constellations that would be visible if the sun were not lighting up the sky.
For all the Douglas Adams fans, a good way to end your visit is a stop to admire the view from the Café at the End of the Universe.
from a March 27, 2008 visit to Griffith Observatory by Chris and Ragna Blanco. All photos courtesy Christian Blanco.
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Obelisk
One of the first sights at the Observatory is an obelisk dedicated to six of the greatest astronomers of all time: Hipparchus, Copernicus, Galileo, Kepler, Newton, and Herschel.
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Sundial
Just to the south of the obelisk of that is a beautiful sundial showing the time of day.
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One Foot = 20,000,000 miles
As you walk down the front pathway, you’ll notice brass lines inlaid into the cement, each labeled with a different planet’s name. Near to the entrance of the observatory is the Sun itself. Each planet’s orbit is laid out throughout the observatory’s grounds to a scale where one foot is equal to about 20,000,000 miles.
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Pendulum
a giant pendulum; set to swing from a bearing in the ceiling in order to show the Earth’s spin—the pendulum’s orientation appears to change as the earth turns.
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Sundial for the Date
The Observatory’s second sundial tells not the time, like most sundials, but instead the date.
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Café at the End of the Universe
For all the Douglas Adams fans, a good way to end your visit is a stop to admire the view from
the Café at the End of the Universe.
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European Sundial
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European Sundial
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European Sundial
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European Sundial
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European Sundial
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University of Washington Sundial
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Sundial
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Sundial
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Sundial
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One of the most important tools that astronomers always use, they rarely talk about as such, perhaps because even the wisest of them find it is impossible to define.
We do often overlook tools such as mathematics and writing. Measurements (addition, geometry, etc.) are indispensable in astronomy. 
And yet, it’s next to impossible to work in astronomy without using either tool. We measure star distances by the time it takes light to travel from one place to another. We measure the existence of the Earth in the number of times that it has gone around the Sun; and we count the age of the universe in years relative to Earth-years. We rely on an inverse spherical map of the sky with its east-west grid (right ascension) determined by the degrees of distance east to west relative to the time required for a cyclical rotation of the stars throughout our year.
P.O. Box 10914, Bainbridge Island, WA 98110
http://www.bpastro.org/
Ritchie Observatory, Battle Point Park
(206)842-9152
Harry Colvin, President
(206)842-6617, hcolvin1@comcast.net
Mike Browning, Vice President
(206)861-1630, bjjm@qwest.net
Russell M. Heglund, Secretary
(206)842-8758, rmheglund@yahoo.com
Frank Schroer, Treasurer
(206)842-1974, frank@schroer.net
Nels Johansen, Facilities Officer
(206)842-7968
Stephen Ruhl, Education Officer
(206)855-7883, education@bpastro.org
Malcolm Saunders, Chief Astronomer
(206)780-1905, astronomer@bpastro.org
Edward M. (Mac) Gardiner
President Emeritus/Founder
(206)842-3717, macg@bainbridge.net
Ed Ritchie, Chief Astronomer/Founder 1993-1997
John H. Rudolph, Facility Director/Founder 1993-2003 
