While low pressure systems are normally associated with cloud and rain, this particular low lies beneath an upper level high which suppresses the formation of cloud. A weak frontal system extends from northern Iran to the Mediterranean coast, separating moderate temperatures and moisture on the north side from the semi-arid airmasses to the south. Upper level winds tend to flow from the west in northern Turkey and from the east in more southerly parts along the track. The narrow coastal plain along the Black Sea coast of Turkey has a Mediterranean climate and represents the airmasses north of the front. This area has sufficient moisture to grow figs, olives, tea and tobacco. Most of the rain falls in winter, but steady northwest winds in the summer season bring occasional convective clouds with showers and thundershowers. The eclipse comes ashore at a remote part of the Turkish coastline near the town of Cide. To the east of the shadow path is Sinop, an ancient city of Greek and Byzantine origins. Its most famous native son was Diogenes the Cynic, who is reputed to have replied to Alexander the Great when asked what Alexander could do for him, "Yes, stand aside, you're blocking my light," ­ a perfect quotation (though not sentiment) to go with a solar eclipse [Ayliffe et al. 1994]. The scenic road to the center line winds closely along the coast, forced to the edge of the sea by a range of 2000 meter mountains which line the Black Sea coast. Cide, a few kilometers inland from the sea, has a 10 km long pebbly beach nearby which could provide a site to watch the eclipse. Travel time from Sinop to Cide is about two hours. West of the center line is the regional capital Zonguldak, slightly closer than Sinop, and with good transportation connections to Ankara. The steady onshore winds along the coast promote the development of convective cloudiness as they rise up the mountain slopes which line the sea, but cloud statistics for Zonguldak and Sinop promise weather at least as favorable as on the Bulgarian coast. Farther south, the track reaches Sivas on the eastern edge of the Anatolian Plateau. This city of magnificent Selçuk monuments has a history extending from Hittite times to the formation of modern Turkey. The frequency of days with scattered cloud rises rapidly here as downslope winds from the surrounding mountains dry the air. Much of the meager cloudiness is due to occasional summer thundershowers, though the incidence of rainy days is dwindling rapidly. Nevertheless, some of these thunderstorms can bring violent weather with widespread cloudiness. As in eastern Europe, they are primarily an afternoon event, but because the eclipse is later in Turkey and the heating of the ground more pronounced, thunderstorms are more likely here than in Europe at eclipse time. Beyond Sivas the shadow bounces across the eastern limb of the Taurus Mountains, with gradually improving prospects for good eclipse weather. When the shadow path finally departs the Taurus Mountains it descends into the Tigris Valley and reaches Dyarbakir, a sprawling city with a large Kurdish population. The political turmoil of the area has converted Dyarbakir into a large military outpost, enhanced by the presence of a large NATO air base with shrieking jets and thumping helicopter rotors. Weather prospects are excellent (in spite of the anomalous "% of Possible Sunshine" in Table 38) as August is the hottest and driest month of the year. Statistics for the area show that only scattered clouds can be found at eclipse time on 24 to 28 days of the month, and nearly 30 days at the border with Syria. The viewing probability in Figure 23 rises above 80% as thunderstorms almost cease to be a threat, and the eclipse track moves into its most promising arena. Mountainous terrain intervenes again as the eclipse path moves across Kurdistan into Iraq. It is a volatile area and best left alone, in spite of the clear skies. Travelers here must contend with a region in turmoil and will have to have a special quest for adventure. Even better weather and a more stable political climate comes in Iran where the track leaves the Zagros Mountains and moves onto the desert plateau. This is an arid area with temperatures approaching 50° C. The low humidity makes the heat somewhat more bearable (as will the cooling with an eclipse), but by the time the track reaches the Pakistan border, sultry humidities from the Gulf of Oman promise less pleasant observing conditions. Skies are nearly cloudless over Iran for the most part, except for the occasional patches of scattered convective clouds and light showers. These are usually weak enough that they will succumb readily to the cooling which comes with the eclipse. Figure 23 shows that the apex of the eclipse viewing prospects is reached at Esfahan in southern Iran. Sites here have a 96% chance of seeing the Sun on August 11.

Pakistan and India

In August the southwest monsoon season over India is just past its peak, though still in full sway. This humid, wet and cloudy season does not retreat from eastern Pakistan until early September, too late to affect the eclipse. Cloud conditions over western Pakistan are heavier than over Iran because of the abundant moisture available from the Arabian Sea and the convection-promoting influence of the monsoon. Statistics for Karachi show a dramatic decline in the frequency of days with scattered cloud, though not in the number of days with rain.

As the track moves into India, the low Sun angle, late hour, and the extensive cloudiness of the Indian monsoon bring the poorest conditions of anywhere along the track. Satellite pictures reveal a land cloaked in cloud day after day and the probability of seeing the eclipse declines rapidly. By the time the shadow reaches the sunset terminator, the chances of seeing the eclipse have dropped almost to zero.

The Atlantic Ocean and the Black Sea

The proximity of the sunrise eclipse to Nova Scotia will undoubtedly tempt some observers to try a ship-board expedition from the eastern seaboard of North America. Though skies have a high frequency of cloud cover, the mobility offered by a ship should be able to overcome this deficiency, to some extent, provided good weather advice is available. The very low Sun angle at the start of the eclipse will seriously impede the search for a hole in any cloud cover which might be there, but provided the excursion is not just a day trip with little time for exploration, the effort has a good chance of being rewarded. Black Sea prospects are comparable to nearby lands enjoying favorable climate statistics and the diminished influence of the variable westerlies. Mobility offers advantages similar to those described above. Mean wave heights in the western Atlantic range between 1 and 1.5 meters off of the Nova Scotia coast, making time-exposure photography a little challenging, particularly through a telescope. Waves on the much smaller Black Sea tend to keep under 0.5 meters except near the Turkish coast where the prevailing winds have the entire length of the sea to build wave heights.

Coping with the Weather on Eclipse Day

From England to Romania and Bulgaria, eclipse day will be subject to the vagaries of the westerly winds which carry highs and lows across the European continent. While climatology offers some advice for long range planning, mobile eclipse observers will almost certainly be able to find a view of the Sun on August 11. Particularly in western Europe, where the collection of climate statistics over the decades does not favor one location over another, the ability to respond to short and long-range weather forecasts will be very helpful. Modern meteorology is capable of producing detailed computer forecasts which stretch for ten days into the future. These forecasts can be assessed early enough to make general travel plans which can then be refined as eclipse day approaches. Long range (5-10 day) computer forecasts are notoriously inaccurate and must be used with care. They should be used only for long range planning, to pick a general area for travel, as they are likely to show many changes before August 11 arrives. The best sites will lie beneath an upper level ridge ahead of, or in, a surface high pressure region, if these structures are forecast. This does not guarantee good weather, but it does greatly enhance one's prospects. If the numerical models don't predict these conditions, then more sophisticated decisions must be made which will probably require the services of a meteorologist. Computer forecasts become much more reliable within five days, and still more accurate within 48 hours. The amount of detail they reveal also increases, with fields of relative humidity, precipitation, cloud cover, winds and temperature becoming available as the critical date approaches. A logical approach would be to select two or three specific sites within a convenient travel distance at this time, and then make a decision between them at the last possible moment. Long range forecasts for Europe from the National Weather Service (NWS) in the United States and the European Centre for Medium Range Weather Forecasting (ECMWF) are readily available on the World Wide Web from Purdue University and a number of other locations. At Purdue the U.S. medium range forecast (MRF) model is usually available each morning after 12:30 UT. The ECMWF forecast out to six days is also available at the same site. MRF charts show the 500 millibar flow (about 5000 m above the surface) and the surface pressure pattern. Look for an upper level ridge on the 500 mb chart, and the position of highs and lows on the other. These two charts will allow an early evaluation of the weather over Europe (most models are global, though not all parts of the globe are shown in the Web sites). The really hard part is whether or not the models are trustworthy, especially eight or ten days into the future. What clues are available to indicate that the numerical weather patterns will match the real ones on eclipse day? Consistency is one clue ­ is the same general pattern forecast from one day to the next? Another is whether or not two different models forecast the same general patterns. Most likely there will be small differences between the two, but if highs and lows are hundreds of kilometers apart, or upper features don't line up, then use the charts with caution. Try to find a spot which looks good on both charts, and wait another day to see if the agreement improves. Don't finalize long range plans at this stage.

Once the eclipse is within five days, the greater reliability and detail in the models allows serious planning, for now we know not only the location of weather systems, but also how the cloud is draped around them. But be careful! Predictions are not gospel, and thunderstorms especially are difficult to predict with accuracy when more than a day or two away. Low level cloud is often unforecast, or indicated only in a subtle variation in the humidity pattern. Keep looking for the best spot within your travel range according to the position of the low and the upper ridge. By now of course, normal meteorological forecasts will be available and you may simply have to watch the television. Long range forecasts over Turkey and the Middle East are not likely to be as informative as those over Europe, where weather systems are more active and changeable. Individuals and groups who are not mobile may wish to consider sites where climate statistics work in their favor, from Hungary eastward through Turkey, rather than take their chances with the westerlies in western Europe or England.

The Probability of Seeing the Eclipse

When the Sun is high, the probability of seeing an eclipse depends only on the proportion of the sky which is covered by cloud, a factor which is represented by the mean cloudiness of a site. As the altitude of the Sun declines however, the depth of the cloud becomes more important as a restriction to visibility. This is easily understood by considering the effects of a towering thunderstorm ­ if overhead, the blocking capacity depends on the area of the base of the storm. If the thunderstorm is on the horizon, the blocking effect depends on the width of the storm perpendicular to the line of sight and its height. If the average height of clouds in an area and the mean cloud amount are known, then the probability of seeing the eclipse can be calculated for a given solar altitude. Such a calculation is shown in .gif" f = "../figures/figure_Figure 23, using climatological values for these parameters. Adjustments are made for the time of day, since a large part of the cloud cover along the track is convective in nature, and thus dependent on the hour. As with any calculation, the results of Figure 23 should be used cautiously. The climatological data used in the modeling are smoothed out from their true values, and small scale variations are lost or muted. Actual forecasts on and ahead of eclipse day will provide much more information than this figure, though of course they do not permit planning years ahead of time.

Summary

Weather prospects for the eclipse begin in the dismal cloudiness of the North Atlantic and improve steadily along the eclipse track as far as the Middle East. Beyond Iran, cloud cover thickens again and the eclipse ends as it began with diminished promises. The best prospects in Europe are found along the shores of the Black Sea. Iran offers the most favorable weather along the entire track, though cautious observers may prefer the skies of central Turkey.

Weather Web Sites

1. http://www.tvweather.com

A good starting point. This site has many links to current and past weather around the world.

2. http://shark1.esrin.esa.it:80/q_.html" alt = "[Figure ]">interface.html

A source of past satellite pictures around the world from 1992 onward (with gaps). These color pictures will give a feel for the weather over Europe and the Middle East in mid August.

3. http://wxp.atms.purdue.edu/

Purdue University, where the various model forecasts can be obtained. The MRF model is available over Europe for 10 days into the future. The ECMWF forecast can be examined for 6 days ahead. The MRF is available as a 9 panel display of 500 mb and surface features. Both models go as far east as Iraq. Another model, the AVN is available for 72 hours into the future and includes a chart of relative humidity (where 70% RH or higher implies cloud).

4. http://www.meteo.fr/tpsreel/images/satt0.jpg

A current European satellite image is available at Meteo France, as well as other sites.

Observing the Eclipse

Eye Safety And Solar Eclipses

B. Ralph Chou, MSc, OD

Associate Professor, School of Optometry, University of Waterloo

Waterloo, Ontario, Canada N2L 3G1

A total solar eclipse is probably the most spectacular astronomical event that most people will experience in their lives. There is a great deal of interest in watching eclipses, and thousands of astronomers (both amateur and professional) travel around the world to observe and photograph them. A solar eclipse offers students a unique opportunity to see a natural phenomenon that illustrates the basic principles of mathematics and science that are taught through elementary and secondary school. Indeed, many scientists (including astronomers!) have been inspired to study science as a result of seeing a total solar eclipse. Teachers can use eclipses to show how the laws of motion and the mathematics of orbital motion can predict the occurrence of eclipses. The use of pinhole cameras and telescopes or binoculars to observe an eclipse leads to an understanding of the optics of these devices. The rise and fall of environmental light levels during an eclipse illustrate the principles of radiometry and photometry, while biology classes can observe the associated behavior of plants and animals. It is also an opportunity for children of school age to contribute actively to scientific research - observations of contact timings at different locations along the eclipse path are useful in refining our knowledge of the orbital motions of the Moon and earth, and sketches and photographs of the solar corona can be used to build a three-dimensional picture of the Sun's extended atmosphere during the eclipse. However, observing the Sun can be dangerous if you do not take the proper precautions. The solar radiation that reaches the surface of Earth ranges from ultraviolet (UV) radiation at wavelengths longer than 290 nm to radio waves in the meter range. The tissues in the eye transmit a substantial part of the radiation between 380 and 1400 nm to the light-sensitive retina at the back of the eye. While environmental exposure to UV radiation is known to contribute to the accelerated aging of the outer layers of the eye and the development of cataracts, the concern over improper viewing of the Sun during an eclipse is for the development of "eclipse blindness" or retinal burns. Exposure of the retina to intense visible light causes damage to its light-sensitive rod and cone cells. The light triggers a series of complex chemical reactions within the cells which damages their ability to respond to a visual stimulus, and in extreme cases, can destroy them. The result is a loss of visual function which may be either temporary or permanent, depending on the severity of the damage. When a person looks repeatedly or for a long time at the Sun without proper protection for the eyes, this photochemical retinal damage may be accompanied by a thermal injury - the high level of visible and near-infrared radiation causes heating that literally cooks the exposed tissue. This thermal injury or photocoagulation destroys the rods and cones, creating a small blind area. The danger to vision is significant because photic retinal injuries occur without any feeling of pain (there are no pain receptors in the retina), and the visual effects do not occur for at least several hours after the damage is done [Pitts, 1993]. The only time that the Sun can be viewed safely with the naked eye is during a total eclipse, when the Moon completely covers the disk of the Sun. It is never safe to look at a partial or annular eclipse, or the partial phases of a total solar eclipse, without the proper equipment and techniques. Even when 99% of the Sun's surface (the photosphere) is obscured during the partial phases of a solar eclipse, the remaining crescent Sun is still intense enough to cause a retinal burn, even though illumination levels are comparable to twilight [Chou, 1981, 1996; Marsh, 1982]. Failure to use proper observing methods may result in permanent eye damage or severe visual loss. This can have important adverse effects on career choices and earning potential, since it has been shown that most individuals who sustain eclipse-related eye injuries are children and young adults [Penner and McNair, 1966; Chou and Krailo, 1981]. The same techniques for observing the Sun outside of eclipses are used to view and photograph annular solar eclipses and the partly eclipsed Sun [Sherrod, 1981; Pasachoff & Menzel 1992; Pasachoff & Covington, 1993; Reynolds & Sweetsir, 1995]. The safest and most inexpensive method is by projection. A pinhole or small opening is used to form an image of the Sun on a screen placed about a meter behind the opening. Multiple openings in perfboard, in a loosely woven straw hat, or even between interlaced fingers can be used to cast a pattern of solar images on a screen. A similar effect is seen on the ground below a broad-leafed tree: the many "pinholes" formed by overlapping leaves creates hundreds of crescent-shaped images.

Binoculars or a small telescope mounted on a tripod can also be used to project a magnified image of the Sun onto a white card. All of these methods can be used to provide a safe view of the partial phases of an eclipse to a group of observers, but care must be taken to ensure that no one looks through the device. The main advantage of the projection methods is that nobody is looking directly at the Sun. The disadvantage of the pinhole method is that the screen must be placed at least a meter behind the opening to get a solar image that is large enough to see easily. The Sun can only be viewed directly when filters specially designed to protect the eyes are used. Most such filters have a thin layer of chromium alloy or aluminum deposited on their surfaces that attenuates both visible and near-infrared radiation. A safe solar filter should transmit less than 0.003% (density~4.5)¹⁰ of visible light (380 to 780 nm) and no more than 0.5% (density~2.3) of the near-infrared radiation (780 to 1400 nm). Figure 24 shows the spectral response for a selection of safe solar filters. One of the most widely available filters for safe solar viewing is shade number 14 welder's glass, which can be obtained from welding supply outlets. A popular inexpensive alternative is aluminized mylar manufactured specifically for solar observation. ("Space blankets" and aluminized mylar used in gardening are not suitable for this purpose!) Unlike the welding glass, mylar can be cut to fit any viewing device, and doesn't break when dropped. Many experienced solar observers use one or two layers of black-and-white film that has been fully exposed to light and developed to maximum density. The metallic silver contained in the film emulsion is the protective filter. Some of the newer black and white films use dyes instead of silver and these are unsafe. Black-and-white negatives with images on it (e.g., medical x-rays) are also not suitable. More recently, solar observers have used floppy disks and compact disks (both CDs and CD-ROMs) as protective filters by covering the central openings and looking through the disk media. However, the optical quality of the solar image formed by a floppy disk or CD is relatively poor compared to mylar or welder's glass. Some CDs are made with very thin aluminum coatings which are not safe - if you can see through the CD in normal room lighting, don't use it!! No filter should be used with an optical device (e.g. binoculars, telescope, camera) unless it has been specifically designed for that purpose and is mounted at the front end (i.e., end towards the Sun). Some sources of solar filters are listed in the following section. Unsafe filters include all color film, black-and-white film that contains no silver, photographic negatives with images on them (x-rays and snapshots), smoked glass, sunglasses (single or multiple pairs), photographic neutral density filters and polarizing filters. Most of these transmit high levels of invisible infrared radiation which can cause a thermal retinal burn (see Figure 24). The fact that the Sun appears dim, or that you feel no discomfort when looking at the Sun through the filter, is no guarantee that your eyes are safe. Solar filters designed to thread into eyepieces that are often provided with inexpensive telescopes are also unsafe. These glass filters can crack unexpectedly from overheating when the telescope is pointed at the Sun, and retinal damage can occur faster than the observer can move the eye from the eyepiece. Avoid unnecessary risks. Your local planetarium, science center, or amateur astronomy club can provide additional information on how to observe the eclipse safely. There has been concern expressed about the possibility that UVA radiation (wavelengths between 315 and 380 nm) in sunlight may also adversely affect the retina [Del Priore, 1991]. While there is some experimental evidence for this, it only applies to the special case of aphakia, where the natural lens of the eye has been removed because of cataract or injury, and no UV-blocking spectacle, contact or intraocular lens has been fitted. In an intact normal human eye, UVA radiation does not reach the retina because it is absorbed by the crystalline lens. In aphakia, normal environmental exposure to solar UV radiation may indeed cause chronic retinal damage. However, the solar filter materials discussed in this article attenuate solar UV radiation to a level well below the minimum permissible occupational exposure for UVA (ACGIH, 1994), so an aphakic observer is at no additional risk of retinal damage when looking at the Sun through a proper solar filter. In the days and weeks preceding a solar eclipse, there are often news stories and announcements in the media, warning about the dangers of looking at the eclipse. Unfortunately, despite the good intentions behind these messages, they frequently contain misinformation, and may be designed to scare people from seeing the eclipse at all. However, this tactic may backfire, particularly when the messages are intended for students. A student who heeds warnings from teachers and other authorities not to view the eclipse because of the danger to vision, and learns later that other students did see it safely, may feel cheated out of the experience. Having now learned that the authority figure was wrong on one occasion, how is this student

¹⁰ In addition to the term transmittance (in percent), the energy transmission of a filter can also be described by the term density (unitless) where density 'd' is the common logarithm of the reciprocal of transmittance 't' or d = log₁₀[1/t]. A density of '0' corresponds to a transmittance of 100%; a density of '1' corresponds to a transmittance of 10%; a density of '2' corresponds to a transmittance of 1%, etc....

going to react when other health-related advice about drugs, alcohol, AIDS, or smoking is given [Pasachoff, 1997]? Misinformation may be just as bad, if not worse than no information at all. In spite of these precautions, the total phase of an eclipse can and should be viewed without any filters whatsoever. The naked eye view of totality is not only completely safe, it is truly and overwhelmingly awe-inspiring!

Sources for Solar Filters

The following is a brief list of sources for mylar and/or glass filters specifically designed for safe solar viewing with or without a telescope. The list is not meant to be exhaustive, but is simply a representative sample of sources for solar filters currently available in North America and Europe. For additional sources, see advertisements in Astronomy and/or Sky & Telescope magazines. The inclusion of any source on this list does not imply an endorsement of that source by the authors or NASA.

· ABELexpress - Astronomy Division, 230-Y E. Main St., Carnegie, PA 15106. (412) 279-0672

· Celestron International, 2835 Columbia St., Torrance, CA 90503. (310) 328-9560

· Edwin Hirsch, 29 Lakeview Dr., Tomkins Cove, NY 10986. (914) 786-3738

· Meade Instruments Corporation, 16542 Millikan Ave., Irvine, CA 92714. (714) 756-2291

· Orion Telescope Center, 2450 17th Ave., PO Box 1158-S, Santa Cruz, CA 95061. (408) 464-0446

· Pocono Mountain Optics, 104 NP 502 Plaza, Moscow, PA 18444. (717) 842-1500

· Rainbow Symphony, Inc., 6860 Canby Ave., #120, Reseda, CA 91335 (800) 821-5122

· Roger W. Tuthill, Inc., 11 Tanglewood Lane, Mountainside, NJ 07092. (908) 232-1786

· Telescope and Binocular Center, P.O. Box 1815, Santa Cruz, CA 95061-1815. (408) 763-7030

· Thousand Oaks Optical, Box 5044-289, Thousand Oaks, CA 91359. (805) 491-3642

· Khan Scope Centre, 3243 Dufferin Street, Toronto, Ontario, Canada M6A 2T2 (416) 783-4140

· Perceptor Telescopes TransCanada, Brownsville Junction Plaza, Box 38, Schomberg, Ontario, Canada L0G 1T0 (905) 939-2313

· Eclipse 99 Ltd., Belle Etoile, Rue du Hamel, Guernsey GY5 7QJ. 001 44 1481 64847

IAU Solar Eclipse Education Committee

In order to ensure that astronomers and public health authorities have access to information related to safe viewing practices, the International Astronomical Union, the international organization for professional astronomers, set up a Solar Eclipse Education Committee. Under Prof. Jay M. Pasachoff of Williams College, the Committee has assembled information on safe methods of observing the Sun and solar eclipses, eclipse-related eye injuries, and samples of educational materials on solar eclipses. For more information, contact Prof. Jay M. Pasachoff, Hopkins Observatory, Williams College, Williamstown, MA 01267, USA (e-mail: jay.m.pasachoff@williams.edu). Information on safe solar filters can be obtained by contacting Dr. B. Ralph Chou (e-mail: bchou@sciborg.uwaterloo.ca).

Eclipse Photography

The eclipse may be safely photographed provided that the above precautions are followed. Almost any kind of camera with manual controls can be used to capture this rare event. However, a lens with a fairly long focal length is recommended to produce as large an image of the Sun as possible. A standard 50 mm lens yields a minuscule 0.5 mm image, while a 200 mm telephoto or zoom produces a 1.9 mm image. A better choice would be one of the small, compact catadioptic or mirror lenses that have become widely available in the past ten years. The focal length of 500 mm is most common among such mirror lenses and yields a solar image of 4.6 mm. With one solar radius of corona on either side, an eclipse view during totality will cover 9.2 mm.Adding a 2x tele-converter will produce a 1000 mm focal length, which doubles the Sun's size to 9.2 mm. Focal lengths in excess of 1000 mm usually fall within the realm of amateur telescopes. If full disk photography of partial phases on 35 mm format is planned, the focal length of the optics must not exceed 2600 mm. However, since most cameras don't show the full extent of the image in their viewfinders, a more practical limit is about 2000 mm. Longer focal lengths permit photography of only a magnified portion of the Sun's disk. In order to photograph the Sun's corona during totality, the focal length should be no longer than 1500 mm to 1800 mm (for 35 mm equipment). However, a focal length of 1000 mm requires less critical framing and can capture some of the longer coronal streamers. For any particular focal length, the diameter of the Sun's image is approximately equal to the focal length divided by 109 (Table 25). A mylar or glass solar filter must be used on the lens throughout the partial phases for both photography and safe viewing. Such filters are most easily obtained through manufacturers and dealers listed in Sky & Telescope and Astronomy magazines (see: Sources for Solar Filters). These filters typically attenuate the Sun's visible and infrared energy by a factor of 100,000. However, the actual filter factor and choice of ISO film speed will play critical roles in determining the correct photographic exposure. A low to medium speed film is recommended (ISO 50 to 100) since the Sun gives off abundant light. The easiest method for determining the correct exposure is accomplished by running a calibration test on the uneclipsed Sun. Shoot a roll of film of the mid-day Sun at a fixed aperture (f/8 to f/16) using every shutter speed between 1/1000 and 1/4 second. After the film is developed, note the best exposures and use them to photograph all the partial phases. The Sun's surface brightness remains constant throughout the eclipse, so no exposure compensation is needed except for the crescent phases which require two more stops due to solar limb darkening. Bracketing by several stops is also necessary if haze or clouds interfere on eclipse day. Certainly the most spectacular and awe inspiring phase of the eclipse is totality. For a few brief minutes or seconds, the Sun's pearly white corona, red prominences and chromosphere are visible. The great

challenge is to obtain a set of photographs which captures some aspect of these fleeting phenomena. The most important point to remember is that during the total phase, all solar filters must be removed! The corona has a surface brightness a million times fainter than the photosphere, so photographs of the corona are made without a filter. Furthermore, it is completely safe to view the totally eclipsed Sun directly with the naked eye. No filters are needed and they will only hinder your view. The average brightness of the corona varies inversely with the distance from the Sun's limb. The inner corona is far brighter than the outer corona. Thus, no single exposure can capture its full dynamic range. The best strategy is to choose one aperture or f/number and bracket the exposures over a range of shutter speeds (i.e., 1/1000 down to 1 second). Rehearsing this sequence is highly recommended since great excitement accompanies totality and there is little time to think. Exposure times for various combinations of film speeds (ISO), apertures (f/number) and solar features (chromosphere, prominences, inner, middle and outer corona) are summarized in Table 26. The table was developed from eclipse photographs made by Espenak as well as from photographs published in Sky and Telescope. To use the table, first select the ISO film speed in the upper left column. Next, move to the right to the desired aperture or f/number for the chosen ISO. The shutter speeds in that column may be used as starting points for photographing various features and phenomena tabulated in the 'Subject' column at the far left. For example, to photograph prominences using ISO 100 at f/11, the table recommends an exposure of 1/500. Alternatively, you can calculate the recommended shutter speed using the 'Q' factors tabulated along with the exposure formula at the bottom of Table 26. Keep in mind that these exposures are based on a clear sky and a corona of average brightness. You should bracket your exposures one or more stops to take into account the actual sky conditions and the variable nature of these phenomena. Another interesting way to photograph the eclipse is to record its phases all on one frame. This is accomplished by using a stationary camera capable of making multiple exposures (check the camera instruction manual). Since the Sun moves through the sky at the rate of 15 degrees per hour, it slowly drifts through the field of view of any camera equipped with a normal focal length lens (i.e., 35 to 50 mm). If the camera is oriented so that the Sun drifts along the frame's diagonal, it will take over three hours for the Sun to cross the field of a 50 mm lens. The proper camera orientation can be determined through trial and error several days before the eclipse. This will also insure that no trees or buildings obscure the view during the eclipse. The Sun should be positioned along the eastern (left in the northern hemisphere) edge or corner of the viewfinder shortly before the eclipse begins. Exposures are then made throughout the eclipse at ~five minute intervals. The camera must remain perfectly rigid during this period and may be clamped to a wall or post since tripods are easily bumped. If you're in the path of totality, remove the solar filter during the total phase and take a long exposure (~1 second) in order to record the corona in your sequence. The final photograph will consist of a string of Suns, each showing a different phase of the eclipse. Finally, an eclipse effect that is easily captured with point-and-shoot or automatic cameras should not be overlooked. Use a kitchen sieve or colander and allow its shadow to fall on a piece of white card-board placed several feet away. The holes in the utensil act like pinhole cameras and each one projects its own image of the Sun. The effect can also be duplicated by forming a small aperture with one's hands and watching the ground below. The pinhole camera effect becomes more prominent with increasing eclipse magnitude. Virtually any camera can be used to photograph the phenomenon, but automatic cameras must have their flashes turned off since this would otherwise obliterate the pinhole images. For those who choose to photograph this eclipse from one of the many cruise ships in the path, some special comments are in order. Shipboard photography puts certain limits on the focal length and shutter speeds that can be used. It's difficult to make specific recommendations since it depends on the stability of the ship as well as wave heights encountered on eclipse day. Certainly telescopes with focal lengths of 1000 mm or more can be ruled out since their small fields of view would require the ship to remain virtually motionless during totality, and this is rather unlikely even given calm seas. A 500 mm lens might be a safe upper limit in focal length. Film choice could be determined on eclipse day by viewing the Sun through the camera lens and noting the image motion due to the rolling sea. If it's a calm day, you might try an ISO 100 film. For rougher seas, ISO 400 or more might be a better choice. Shutter speeds as slow as 1/8 or 1/4 may be tried if the conditions warrant it. Otherwise, stick with a 1/15 or 1/30 and shoot a sequence through 1/1000 second. It might be good insurance to bring a wider 200 mm lens just in case the seas are rougher than expected. As worst case scenario, Espenak photographed the 1984 total eclipse aboard a 95 foot yacht in seas of 3 feet. He had to hold on with one hand and point his 350 mm lens with the other! Even at that short focal length, it was difficult to keep the Sun in the field. However, any large cruise ship will offer a far more stable platform than this. For more information on eclipse photography, observations and eye safety, see Further Reading in the Bibliography.

Sky At Totality

The total phase of an eclipse is accompanied by the onset of a rapidly darkening sky whose appearance resembles evening twilight about 30 to 40 minutes after sunset. The effect presents an excellent opportunity to view planets and bright stars in the daytime sky. Aside from the sheer novelty of it, such observations are useful in gauging the apparent sky brightness and transparency during totality. The Sun is in Pisces and all five naked eye planets as well as a number of bright stars will be above the horizon for observers within the umbral path. Figure 25 depicts the appearance of the sky during totality as seen from the center line at 11:00 UT. This corresponds to western Romania near the point of greatest eclipse. Mercury (mv=+0.7) and Venus (mv=­3.5) are located 18° west and 15° east of the Sun, respectively, and both will be easily visible during totality. Venus is two months past inferior conjunction while Mercury is one month shy of superior conjunction. As the brightest planet in the sky, Venus can actually be observed in broad daylight provided that the sky is cloud free and of high transparency (i.e., no dust or particulates). Look for the planet during the partial phases by first covering the crescent Sun with an extended hand. Venus will be shining so brightly, it will be impossible to miss during totality. Mercury will prove much more challenging, but not too difficult if the sky transparency is good. Under the right circumstances, it should be possible to view all five classical planets, the Moon and the Sun (or at least its corona) as one's eyes sweep across the darkened sky during totality. A number of the brightest winter/spring stars may also be visible during totality. Regulus (mv=+1.35) is 10° east of the Sun while Castor (mv=+1.94) and Pollux (m_v=+1.14) stand 31° and 28° to the northwest. Procyon (m_v=+0.38) and Sirius (m_v=-1.46) are located 30° and 52° to the southwest, respectively. Betelgeuse (mv=+0.5v) and Rigel (m_v=+0.12) are low in the southwest at 26° and 38°, while Aldebaran (m_v=+0.85) is 20° above the western horizon. Capella (m_v=+0.08) lies 63° to the northwest. Finally, Arcturus (m_v=+1.94) lies due east 30° above the horizon. The following ephemeris [using Bretagnon and Simon, 1986] gives the positions of the naked eye planets during the eclipse. Delta is the distance of the planet from Earth (A.U.'s), V is the apparent visual magnitude of the planet, and Elong gives the solar elongation or angle between the Sun and planet.

Ephemeris: 1999 Aug 11 11:00:00 UT Equinox = Mean Date

Planet RA Dec Delta V Size Phase Elong

" °

Sun 09h23m08s +15°19䙺" 1.01358 -26.7 1893.6 - -

Mercury 08h07m35s +18°08䚈" 0.82062 0.7 8.2 0.30 18.3W

Venus 10h06m46s +04°18䙳" 0.30047 -3.5 55.5 0.04 15.4E

Mars 14h55m32s -18°28䙓" 1.06814 0.3 8.8 0.86 88.5E

Jupiter 02h11m31s +11°47䙴" 4.61411 -2.1 42.7 0.99 103.7W

Saturn 03h00m28s +14°34䙯" 9.13383 0.1 18.2 1.00 91.5W

For sky maps from other locations along the path of totality, see the special web site for the total solar eclipse of 1999: http://sunearth.gsfc.nasa.gov/eclipse/TSE1999/TSE1999.html

Contact Timings from the Path Limits

Precise timings of beading phenomena made near the northern and southern limits of the umbral path (i.e., the graze zones), are of value in determining the diameter of the Sun relative to the Moon at the time of the eclipse. Such measurements are essential to an ongoing project to monitor changes in the solar diameter. Due to the conspicuous nature of the eclipse phenomena and their strong dependence on geographical location, scientifically useful observations can be made with relatively modest equipment. A small telescope, short wave radio and portable camcorder are usually used to make such measurements. Time signals are broadcast via short wave stations WWV and CHU, and are recorded simultaneously as the eclipse is videotaped. If a video camera is not available, a tape recorder can be used to record time signals with verbal timings of each event. Inexperienced observers are cautioned to use great care in making such observations. The safest timing technique consists of observing a projection of the Sun rather than directly imaging the solar disk itself. The observer's geodetic coordinates are required and can be measured from USGS or other large scale maps. If a map is unavailable, then a detailed description of the observing site should be included which provides information such as distance and directions of the nearest towns/settlements, nearby landmarks, identifiable buildings and road intersections. The method of contact timing should be described in detail, along with an estimate of the error. The precisional requirements of these observations are ±0.5 seconds in time, 1" (~30 meters) in latitude and longitude, and ±20 meters (~60 feet) in elevation. Although GPS's (Global Positioning Satellite receivers) are commercially available (~$150 US), their positional accuracy of ±100 meters is about three times larger than the minimum accuracy required by grazing eclipse measurements. GPS receivers are also a useful source for accurate UT. The International Occultation Timing Association (IOTA) coordinates observers world-wide during each eclipse. For more information, contact:

Dr. David W. Dunham, IOTA E-mail: David_Dunham@jhuapl.edu

7006 Megan Lane Phone: (301) 474-4722

Greenbelt, MD 20770-3012, USA

Send reports containing graze observations, eclipse contact and Baily's bead timings, including those made anywhere near or in the path of totality or annularity to:

Dr. Alan D. Fiala

Orbital Mechanics Dept.

U. S. Naval Observatory

3450 Massachusetts Ave., NW

Washington, DC 20392-5420, USA

Plotting the Path on Maps

If high resolution maps of the umbral path are needed, the coordinates listed in Tables 7 and 8 are conveniently provided in longitude increments of 1° and 30' respectively to assist plotting by hand. The path coordinates in Table 3 define a line of maximum eclipse at five minute increments in Universal Time. If observations are to be made near the limits, then the grazing eclipse zones tabulated in Table 8 should be used. A higher resolution table of graze zone coordinates at longitude increments of 7.5' is available via a special web site for the 1999 total eclipse (http://sunearth.gsfc.nasa.gov/eclipse/TSE1999/TSE1999.html). Global Navigation Charts (1:5,000,000), Operational Navigation Charts (scale 1:1,000,000) and Tactical Pilotage Charts (1:500,000) of many parts of the world are published by the National Imagery and Mapping Agency (formerly known as Defense Mapping Agency). Sales and distribution of these maps are through the National Ocean Service (NOS). For specific information about map availability, purchase prices, and ordering instructions, contact the NOS at:

NOAA Distribution Division, N/ACC3 phone: 301-436-8301 National Ocean Service FAX: 301-436-6829 Riverdale, MD 20737-1199, USA

It is also advisable to check the telephone directory for any map specialty stores in your city or metropolitan area. They often have large inventories of many maps available for immediate delivery.

ONC (Operational Navigation Charts) series maps have a larger scale (1:1,000,000) than GNC's appearing in this publication. However, their use here would serve to increase an already record size eclipse bulletin. Instead, we offer a list of ONC maps for plotting the path using data from tables 7 and 8. In particular, the path of totality crosses the following ONC charts:

ONC E-1 England ONC E-2 France, Germany, Austria ONC F-2 Austria, Hungary ONC F-3 Romania, Turkey ONC G-4 Turkey, Syria, Iraq ONC G-6,H-7 Iran ONC H-8 Pakistan, India ONC J8, J-9 India

IAU Working Group on EclipseS

Professional scientists are asked to send descriptions of their eclipse plans to the Working Group on Eclipses of the International Astronomical Union, so that they can keep a list of observations planned. Send such descriptions, even in preliminary form, to:

International Astronomical Union/Working Group on Eclipses Prof. Jay M. Pasachoff, Chair

Williams College­Hopkins Observatory email: jay.m.pasachoff@williams.edu Williamstown, MA 01267, USA FAX: (413) 597-3200

The members of the Working Group on Eclipses of Commissions 10 and 12 of the International Astronomical Union are: Jay M. Pasachoff (USA), Chair; F. Clette (Belgium), F. Espenak (USA); Iraida Kim (Russia); V. Rusin (Slovakia); Jagdev Singh (India); M. Stavinschi (Romania); Yoshinori Suematsu (Japan); consultant: J. Anderson (Canada).

NATO Workshop Proceedings for the 1999 Total Solar Eclipse

In 1996 June 1-5, a special NATO Advanced Research Workshop for "Theoretical and Observational Problems Related to Solar Eclipses" was held in Sinaia, Romania. For the first time in the history of the eclipse observations, observers and theorists were brought together to present and discuss their projects for a future eclipse (1999). Scientific sessions during the meeting covered the following areas:

Principal scientific results from the past eclipse observation. Small and large scale theoretical models of coronal structures. Low temperature structures in coronal environment. Specific problems of solar eclipse observations. Instrumental improvement for future observations. Tasks for Total Solar Eclipse of 11 August 1999. Public education at eclipses and eye safety.

The proceedings from the meeting will be published in 1997 June by Kluwer Academic Publishing (Netherlands) as part of the NATO ASI Series (Z. Mouradian and M. Stavinschi, eds.). For ordering information, please contact:

Dr. Zadig Mouradian email: mouradian@obspm.fr Observatoire de Paris-Meudon FAX: +33.1.4507.7959 DASOP 92195 Meudon Principal FRANCE

Romanian Preparations for 1999 Eclipse

Romanian astronomers have established the International Association ECLIPSA'99 for the purpose of assisting both the scientific community and the general public. In addition to carrying out a series of scientific eclipse observations, ECLIPSA'99 will also play an important role in public education so that everyone can enjoy this extraordinary astronomical event. We plan to set up a new telescope outside the Capital, to complete the observation and data bases of the three observatories of the Astronomical Institute of the Romanian Academy, as well as to built a great Planetarium at Bucharest Observatory, in the immediate vicinity of the Park "Charles the 1st". Through a system of scholarships and awards, ECLIPSA'99 aims to specially train the staff necessary in the eclipse observation. Naturally, we will not leave out the amateur astronomers in view of the important contribution they have brought to the development of astronomy. Throughout the preparations, ECLIPSA'99 will carry out an ample program of national and international conferences and symposia, the publication of specialized and advertising materials, as well as of its own journal "Eclipsa"; it will also conduct an ample publicity campaign both at home and abroad. To accomplish its aims ECLIPSA'99 is carrying on collaborations with similar institutions at home and abroad, with specialists in related fields, as well as with agencies and other institutions in the fields of culture, tourism, transport, trade, etc.. The funds of ECLIPSA'99 come from subscriptions, as well as from legacies and donations from home and abroad. ECLIPSA'99 will not stop its activity after the eclipse. At that time, it will become the International Association ASTRONOMIA 21, whose goal will be to keep alive the interest in this old and, at the same time, modern science. For more information please contact:

Dr. Magdalena Stavinschi email: magda@roastro.astro.ro Astr. Inst. of the Romanian Academy Phone: +40.1.336 36 87 Str. Cutitul de Argint 5 FAX: +40.1.337 33 89 RO-75212 Bucharest ROMANIA

JOSO Working Group for 1999 Eclipse

In October 1995, the Joint Organization for Solar Observations (JOSO), a European consortium of observing solar physicists, created a new working group dedicated to the preparation of the 1999 eclipse.

This Working Group (WG7) will prompt collaborations between scientific teams coming from European countries and other parts of the world to observe the eclipse, and the local scientific and academic organizations in the path of totality, by gathering and distributing information about existing resources and requirements for the practical organisation of scientific expeditions. Another WG7 project is to disseminate to the general public basic but reliable information about the 1999 event and safe eclipse viewing . All groups who are planning to set up a scientific eclipse program are invited to join this new community. For more information, contact:

Dr. Frederic Clette - JOSO WG 7 email: fred@oma.be Observatoire Royal de Belgique FAX: +32.2.373.02.24 Avenue Circulaire, 3 B-1180 Bruxelles BELGIUM JOSO Web site : http://joso.oat.ts.astro.it/

Eclipse Data on Internet

NASA Eclipse Bulletins on Internet

To make the NASA solar eclipse bulletins accessible to as large an audience as possible, these publications are also available via the Internet. This was made possible through the efforts and expertise of Dr. Joe Gurman (GSFC/Solar Physics Branch). All future eclipse bulletins will be available via Internet. NASA eclipse bulletins can be read or downloaded via the World-Wide Web using a Web browser (e.g.: Netscape, Microsoft Explorer, etc.) from the GSFC SDAC (Solar Data Analysis Center) Eclipse Information home page, or from top-level URL's for the currently available eclipse bulletins themselves:

http://umbra.nascom.nasa.gov/eclipse/ (SDAC Eclipse Information)

http://umbra.nascom.nasa.gov/eclipse/941103/rp.html (1994 Nov 3) http://umbra.nascom.nasa.gov/eclipse/951024/rp.html (1995 Oct 24) http://umbra.nascom.nasa.gov/eclipse/970309/rp.html (1997 Mar 9) http://umbra.nascom.nasa.gov/eclipse/980226/rp.html (1998 Feb 26) http://umbra.nascom.nasa.gov/eclipse/990811/rp.html (1999 Aug 11)

The original Microsoft Word text files and PICT figures (Macintosh format) are also available via anonymous ftp. They are stored as BinHex-encoded, StuffIt-compressed Mac folders with .hqx suffixes. For PC's, the text is available in a zip-compressed format in files with the .zip suffix. There are three sub directories for figures (GIF format), maps (JPEG format), and tables (html tables, easily readable as plain text). For example, NASA RP 1344 (Total Solar Eclipse of 1995 October 24 [=951024]) has a directory for these files is as follows: file://umbra.nascom.nasa.gov/pub/eclipse/951024/RP1344text.hqx file://umbra.nascom.nasa.gov/pub/eclipse/951024/RP1344PICTs.hqx file://umbra.nascom.nasa.gov/pub/eclipse/951024/ec951024.zip file://umbra.nascom.nasa.gov/pub/eclipse/951024/figures (directory with GIF's) file://umbra.nascom.nasa.gov/pub/eclipse/951024/maps (directory with JPEG's) file://umbra.nascom.nasa.gov/pub/eclipse/951024/tables (directory with html's)

Other eclipse bulletins have a similar directory format. Current plans call for making all future NASA eclipse bulletins available over the Internet, at or before publication of each. The primary goal is to make the bulletins available to as large an audience as possible. Thus, some figures or maps may not be at their optimum resolution or format. Comments and suggestions are actively solicited to fix problems and improve on compatibility and formats.

Future Eclipse Paths on Internet

Presently, the NASA eclipse bulletins are published 24 to 36 months before each eclipse. However, there have been a growing number of requests for eclipse path data with an even greater lead time. To accommodate the demand, predictions have been generated for all central solar eclipses from 1995 through 2005 using the JPL DE/LE 200 ephemerides. All predictions use the Moon's center of mass; no corrections have been made to adjust for center of figure. The value used for the Moon's mean radius is k=0.272281. The umbral path characteristics have been predicted at 2 minute intervals of time compared to the 6 minute interval used in Fifty Year Canon of Solar Eclipses: 1986-2035 [Espenak, 1987]. This should provide enough detail for making preliminary plots of the path on larger scale maps. Note that positive latitudes are north and positive longitudes are west. A list of currently available eclipse paths includes:

1998 February 26 ­ Total Solar Eclipse 1998 August 22 ­ Annular Solar Eclipse 1999 February 16 ­ Annular Solar Eclipse 1999 August 11 ­ Total Solar Eclipse 2001 June 21 ­ Total Solar Eclipse 2001 December 14 ­ Annular Solar Eclipse

2002 June 10 ­ Annular Solar Eclipse 2002 December 04 ­ Total Solar Eclipse 2003 May 31 ­ Annular Solar Eclipse 2003 November 23 ­ Total Solar Eclipse 2005 April 08 ­ Annular/Total Solar Eclipse 2005 October 03 ­ Annular Solar Eclipse

URL: http://umbra.nascom.nasa.gov/eclipse/predictions/year-month-day.html

The tables can be accessed through the SDAC Eclipse Information home page, or directly from the above URL For example, the eclipse path of 1999 August 11 would use the above address with the string "year-month-day" replaced by "1999-august-11". Send comments, corrections, suggestions or requests for more detailed 'ftp' instructions, to Fred Espenak via e-mail (espenak@lepvax.gsfc.nasa.gov). For Internet related problems, please contact Joe Gurman (gurman@uvsp.nascom.nasa.gov).

Downloading Bulletins and Path Tables Via Anonymous FTP

The eclipse bulletins and path tables are also available via anonymous ftp for sites which do not have access to the World Wide Web. A user first ftp's to umbra.nascom.nasa.gov (150.144.30.134), using the username "anonymous" and password "<username>@<host>". Note that the password is your e-mail address where <username> is your name and <host> is the fully qualified Internet address of your machine (e.g.- gurman@uvsp.nascom.nasa.gov). Next, you change directory with the command "cd pub/eclipse". There are five directories 941103, 951024, 970309, 980226, and 990811; one for each of the last five eclipse bulletins (1318, 1344, 1369, 1398, and 1398 respectively). In each, there is a flat ASCII README file and two .hqx files: RPnnnntext.hqx and RPnnnnPICTS.hqx, where "nnnn" is the Reference Publication number. All .hqx files are BinHex-encoded (ASCII), StuffIt-compressed files for the Macintosh. There's also one .zip file: ecyymmdd.zip, where "yymmdd" is the date of the eclipse. This is a zip-compressed and encoded file for PC's. There are also three subdirectories, figures, maps, and tables, with (respectively), the GIF figures, the JPEG GNC charts, and the html tables (easily readable as plain text). For example, the total solar eclipse of 970309 (= 1997 Mar 9) and published as NASA RP 1369 has a directory for these files is as follows: file://umbra.nascom.nasa.gov/pub/eclipse/970309/README file://umbra.nascom.nasa.gov/pub/eclipse/970309/RP1369text.hqx file://umbra.nascom.nasa.gov/pub/eclipse/970309/RP1369PICTs.hqx file://umbra.nascom.nasa.gov/pub/eclipse/970309/ec970309.zip file://umbra.nascom.nasa.gov/pub/eclipse/970309/figures (directory with GIF's) file://umbra.nascom.nasa.gov/pub/eclipse/970309/maps (directory with JPEG's) file://umbra.nascom.nasa.gov/pub/eclipse/970309/tables (directory with html's)

Directories for analogous files for other solar eclipses are arranged similarly. The html files should be downloaded in ASCII mode and the other files in binary (IMAGE) mode. If you are not using a Web viewer to access the ftp documents, you must first type either "ascii" or "binary" to download an ASCII or a binary file, respectively. You then download the file using the ftp protocol for your particular machine.

Special Web Site for 1999 Solar Eclipse

A special web site has been set up to supplement this bulletin with additional predictions, tables and data for the total solar eclipse of 1999. Some of the data posted there include an expanded version of Table 8 (Mapping Coordinates for the Zones of Grazing Eclipse), and local circumstance tables with many more cities as well as for astronomical observatories. Also featured will be higher resolution maps of selected sections of the path of totality and limb profile figures for a range of locatiions/times along the path. The URL of this special site is:

http://sunearth.gsfc.nasa.gov/eclipse/TSE1999/TSE1999.html

Total Solar Eclipse of 2001 June 21

The next total eclipse of the Sun is the first one of the twenty-first century. The path of the Moon's umbral shadow begins in the South Atlantic, off the east coast of Uruguay and continues across the Atlantic where it reaches the west coast of Africa. The shadow enters Angola in the early afternoon with a center line duration of 4 ¹/2 minutes ( Figure 26). Traveling eastward, the path sweeps through Zambia, Zimbabwe and Mozambique. At that point, the central duration drops to three minutes with the late afternoon Sun 23° above the horizon. Swiftly crossing the Mozambique Channel, the path intercepts southern Madagascar where the central duration lasts 2 ¹/2 minutes with a Sun altitude of 11°. The path ends two minutes later in the Indian Ocean. Complete details will be published in the next NASA bulletin scheduled for Fall-Winter 1997.

Predictions for Eclipse Experiments

This publication has attempted to provide comprehensive information on the 1999 total solar eclipse to both the professional and amateur/lay communities. However, certain investigations and eclipse experiments may require additional information which lies beyond the scope of this work. We invite the international professional community to contact us for assistance with any aspect of eclipse prediction including predictions for locations not included in this publication, or for more detailed predictions for a specific location (e.g.: lunar limb profile and limb corrected contact times for an observing site). This service is offered for the 1998 eclipse as well as for previous eclipses in which analysis is still in progress. To discuss your needs and requirements, please contact Fred Espenak (espenak@lepvax.gsfc.nasa.gov).

Algorithms, Ephemerides and Parameters

Algorithms for the eclipse predictions were developed by Espenak primarily from the Explanatory Supplement [1974] with additional algorithms from Meeus, Grosjean and Vanderleen [1966] and Meeus [1982]. The solar and lunar ephemerides were generated from the JPL DE200 and LE200, respectively. All eclipse calculations were made using a value for the Moon's radius of k=0.2722810 for umbral contacts, and k=0.2725076 (adopted IAU value) for penumbral contacts. Center of mass coordinates were used except where noted. Extrapolating from 1996 to 1998, a value for T of 64.6 seconds was used to convert the predictions from Terrestrial Dynamical Time to Universal Time. The international convention of presenting date and time in descending order has been used throughout the bulletin (i.e., year, month, day, hour, minute, second). The primary source for geographic coordinates used in the local circumstances tables is The New International Atlas (Rand McNally, 1991). Elevations for major cities were taken from Climates of the World (U. S. Dept. of Commerce, 1972). All eclipse predictions presented in this publication were generated on a Macintosh PowerPC 8500 computer. Word processing and page layout for the publication were done using Microsoft Word v5.1. Figures were annotated with Claris MacDraw Pro 1.5. Meteorological diagrams were prepared using Corel Draw 5.0 and converted to Macintosh compatible files. Finally, the bulletin was printed on a 600 dpi laser printer (Apple LaserWriter Pro). The names and spellings of countries, cities and other geopolitical regions are not authoritative, nor do they imply any official recognition in status. Corrections to names, geographic coordinates and elevations are actively solicited in order to update the data base for future eclipses. All calculations, diagrams and opinions presented in this publication are those of the authors and they assume full responsibility for their accuracy.

Bibliography

References

Bretagnon, P., and Simon, J. L., Planetary Programs and Tables from ­4000 to +2800, Willmann-Bell, Richmond, Virginia, 1986.

Climates of the World, U. S. Dept. of Commerce, Washington DC, 1972.

Dunham, J. B, Dunham, D. W. and Warren, W. H., IOTA Observer's Manual, (draft copy), 1992.

Espenak, F., Fifty Year Canon of Solar Eclipses: 1986­2035, NASA RP-1178, Greenbelt, MD, 1987.

Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac, Her Majesty's Nautical Almanac Office, London, 1974.

Herald, D., "Correcting Predictions of Solar Eclipse Contact Times for the Effects of Lunar Limb Irregularities," J. Brit. Ast. Assoc., 1983, 93, 6.

Meeus, J., Astronomical Formulae for Calculators, Willmann-Bell, Inc., Richmond, 1982.

Meeus, J., Grosjean, C., and Vanderleen, W., Canon of Solar Eclipses, Pergamon Press, New York, 1966.

Morrison, L. V., "Analysis of lunar occultations in the years 1943­1974," Astr. J., 1979, 75, 744.

Morrison, L. V., and Appleby, G. M., "Analysis of lunar occultations - III. Systematic corrections to Watts' limb-profiles for the Moon," Mon. Not. R. Astron. Soc., 1981, 196, 1013.

The New International Atlas, Rand McNally, Chicago/New York/San Francisco, 1991.

van den Bergh, G., Periodicity and Variation of Solar (and Lunar) Eclipses, Tjeenk Willink, Haarlem, Netherlands, 1955.

Watts, C. B., "The Marginal Zone of the Moon," Astron. Papers Amer. Ephem., 1963, 17, 1-951.

Meteorology and Travel

Ayliffe, Rosie, Marc Dubin and John Gawthrop, Turkey, The Rough Guides, London, 1994.

Chandler, T.J. and S. Gregory, eds., The Climate of the British Isles, Longman, London and New York, 1976.

Manley, Gordon, "The Climate of the British Isles", in Wallen, C.C. (ed.), Climates of Northern and Western Europe, World Survey of Climatology Volume 5, Elsevier Publishing Co., Amsterdam, London, New York, 1970.

Stanley, David, Eastern Europe, Lonely Planet Publications, Hawthorn, Australia, 1995.

Takahashi, K., and H. Arakawa, Climates of Southern and Western Asia, World Survey of Climatology, Volume 9. Elsevier Publishing Co., Amsterdam, London, New York, 1981.

Warren, Stephen G., Carole J. Hahn, Julius London, Robert M. Chervin and Roy L. Jenne, Global Distribution of Total Cloud Cover and Cloud Type Amounts Over Land, National Center for Atmospheric Research, Boulder, CO., 1986.

Eye Safety

American Conference of Governmental Industrial Hygienists, "Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices," ACGIH, Cincinnati, 1996, p.100.

Chou, B. R., "Safe Solar Filters," Sky & Telescope, August 1981, p. 119.

Chou, B. R., "Eye safety during solar eclipses - myths and realities," in Z. Madourian & M. Stavinschi (eds.) Theoretical and Observational Problems Related to Solar Eclipses, Proceedings of a NATO Advanced Research Workshop. Kluwer Academic Publishers, Dordrecht, 1996 (in press).

Chou, B. R. and Krailo M. D., "Eye injuries in Canada following the total solar eclipse of 26 February 1979," Can. J. Optometry, 1981, 43(1):40.

Del Priore, L. V., "Eye damage from a solar eclipse" in M. Littman and K. Willcox, Totality: Eclipses of the Sun, University of Hawaii Press, Honolulu, 1991, p. 130.

Marsh, J. C. D., "Observing the Sun in Safety," J. Brit. Ast. Assoc., 1982, 92, 6.

Penner, R. and McNair, J. N., "Eclipse blindness - Report of an epidemic in the military population of Hawaii," Am. J. Ophthalmology, 1966, 61:1452.

Pitts D. G., "Ocular effects of radiant energy," in D. G. Pitts & R. N. Kleinstein (eds.) Environmental Vision: Interactions of the Eye, Vision and the Environment, Butterworth-Heinemann, Toronto, 1993, p. 151.

Further Reading

Allen, D., and Allen, C., Eclipse, Allen & Unwin, Sydney, 1987.

Astrophotography Basics, Kodak Customer Service Pamphlet P150, Eastman Kodak, Rochester, 1988.

Brewer, B., Eclipse, Earth View, Seattle, 1991.

Covington, M., Astrophotography for the Amateur, Cambridge University Press, Cambridge, 1988.

Espenak, F., "Total Eclipse of the Sun," Petersen's PhotoGraphic, June 1991, p. 32.

Fiala, A. D., DeYoung, J. A., and Lukac, M. R., Solar Eclipses, 1991­2000, USNO Circular No. 170, U.S. Naval Observatory, Washington, DC, 1986.

Golub, L., and Pasachoff, J. M., The Solar Corona, Cambridge University Press, Cambridge, 1997.

Harris, J., and Talcott, R., Chasing the Shadow, Kalmbach Pub., Waukesha, 1994.

Littmann, M., and Willcox, K., Totality, Eclipses of the Sun, University of Hawaii Press, Honolulu, 1991.

Lowenthal, J., The Hidden Sun: Solar Eclipses and Astrophotography, Avon, New York, 1984.

Mucke, H., and Meeus, J., Canon of Solar Eclipses: ­2003 to +2526, Astronomisches Büro, Vienna, 1983.

North, G., Advanced Amateur Astronomy, Edinburgh University Press, 1991.

Oppolzer, T. R. von, Canon of Eclipses, Dover Publications, New York, 1962.

Ottewell, G., The Under-Standing of Eclipses, Astronomical Workshop, Greenville, NC, 1991.

Pasachoff, J. M., "Solar Eclipses and Public Education," International Astronomical Union Colloquium #162: New Trends in Teaching Astronomy, D. McNally, ed., London 1997, in press.

Willcox, Totality: Eclipses of the Sun., University of Hawaii Press, Honolulu, 1991, p. 130.Pasachoff, J. M., and Covington, M., Cambridge Guide to Eclipse Photography, Cambridge University Press, Cambridge and New York, 1993.

Pasachoff, J. M., and Menzel, D. H., Field Guide to the Stars and Planets, 3rd edition, Houghton Mifflin, Boston, 1992.

Reynolds, M. D. and Sweetsir, R. A., Observe Eclipses, Astronomical League, Washington, DC, 1995.

Sherrod, P. C., A Complete Manual of Amateur Astronomy, Prentice-Hall, 1981.

Zirker, J. B., Total Eclipses of the Sun, Princeton University Press, Princeton, 1995.