Rare Eclipse of the star 32 Lyncis by the asteroid (372) Palma, Friday Morning, Jan. 26, 2007
We need YOUR help to observe, and encourage others to observe, this rare opportunity to measure the size and shape of an asteroid
New weather forecast looks good now for most observers; cold for most & maybe a little less windy; 5th station list
Updated: 2007 January 25 UT, 20h UT (Jan. 25 pm EST)
Full-sky finder charts and descriptions are included to help novice observers locate the target star - see the SKY CHARTS section below. Another way to find the target star, perhaps easier than the method using Talitha, is described. Standard broadcast radio stations that can be used for timing are listed. You should also read the "observing in cold weather" section. The station list has been updated a 5th and final time. INTRODUCTION This is the best eclipse of a star by an asteroid in the U.S.A. in many years, possibly since September 1983, when 40 observers from Alabama to southeastern Virginia timed the eclipse of a slightly brighter star by the asteroid (51) Nemausa. The star, at "magnitude" 6.3, is just barely visible to the naked eye for those in a dark location with good eyesight, but can be seen easily with binoculars by anyone able to find it. This rare eclipse will be visible from a wide path that extends across the U.S.A. from the Delmarva Peninsula (where it will occur at 4:44 am Eastern Standard Time, or EST) to northern California, where it will occur 3 minutes later, at 1:47 am Pacific Standard Time (PST). Astronomers call such an event an "occultation" (from the Latin for the act of hiding) and that is the term that will usually be used below. Last night, Mark Williams interviewed me about the occultation; you can hear the podcast on his Web site. WHAT YOU WILL SEE For those near the center of the path of visibility of the occultation, the event will last almost 15 seconds, and possibly even a little longer if the asteroid is not circular and its long dimension is aligned near the direction of motion. In binoculars, the star will just abruptly vanish from sight when Palma reaches it, and just as suddenly reappear several seconds later. Those with moderate-sized telescopes will be able to see the asteroid, which at 10th "magnitude" will be about 50 times fainter than the star. If the star is a previously-unknown very close double star (we have no information indicating that it is, but these observations can resolve double stars that even the most powerful telescopes can't see directly), it could disappear and reappear in quick steps, or a companion star might not be eclipsed by the asteroid and remain visible during the event. Also, dozens of asteroids are now known to have satellites, but Palma is not one of them. However, a small moon of Palma might not have been found by other techniques, but could occult the star (see a section about this below) as seen from anywhere in the U.S.A. except Alaska (around 11:52 pm Hawaiian Standard Time Thursday evening, Jan. 25, in Hawaii). So virtually anyone in the U.S.A. with binoculars or a telescope has a chance to discover a small moon of Palma. OBSERVING THE OCCULTATION Anyone with a pair of binoculars, or small telescope, within or near the predicted path is encouraged to try to observe the occultation, and to try to time its duration if an occultation occurs. The detail of the asteroid that we can obtain is proportional to the number of separate locations from which the occultation can be observed. Since 32 Lyncis will be above the horizon most of the night, you can practice finding it Thursday evening, Jan. 25, before you go to bed. Since you only need to watch the star for 2 or 3 minutes, you should be able to lose less than half an hour's sleep to make the observation from your home. Simple methods for timing the occultation are described in this Word file, written for observers in the Washington, DC region, but most of the basic timing methods can be used by observers throughout the USA. Those who don't have access to GPS video time inserters or shortwave radios for WWV at 5 and 10 megahertz can use the following standard broadcast stations with their car or other ordinary radio for timing, since others will be making a master tape of their broadcast around the time of the event along with WWV: WHAS 840 kilocycles 50,000-watt clear channel station in Louisville, KY It should be possible to use this in most areas east of the Rockies, but maybe not as far east as Virginia or as far west as Wyoming. WTOP 103.5 FM, Rockville, MD, covers the Washington, DC region, most of central MD and northern VA. XM 123 satellite radio news across the USA, for those with XM receivers; you must use an XM antenna with your FM radio for this; any other form of the broadcast won't work since it will have a different time delay. Of the stations above, WHAS is the best one to use if you can receive it well enough (doesn't have to be perfectly clear reception). I may run out of time and not be able to record WTOP and XM 123 before and during the occultation, so keep recording at least until 9:50 UT, by which time I will certainly be recording them, alternating between them, with WWV and/or GPS time-inserted calibration (I'll be recording with a camcorder). Derek Breit also plans to record a station in northern California, but he won't know which one until he gets in the area. He will have e-mail at least breifly while he's there (he's travelling there now); send him a message at breit_ideas@hotmail.com asking for it if it would help your effort (another observer will be depending on it). He suggests a good time for observers to contact him by e-mail will be 4 pm PST today (That's 0h UT of Jan. 26 UT). THE PATH ACROSS THE USA The path of the occultation across the USA is shown between the two parallel solid lines on the first slide of this Power Point file. The location of the path is not perfectly known; it could shift a little north or south of the area shown. There is a 16% chance that the northern edge of the path could be as far north as the dashed line just north of the northern solid line, and a similar chance that the southern edge could be as far south as the dashed line just south of the southern solid line. The first slide is from Steve Preston's Web site; slides two to five show the path in more detail relative to major highways and cities on 4 separate maps roughly corresponding to the path across the four continental USA time zones; and the sixth slide shows the northern limit in detail over the Washington, DC region. The last 5 slides were created from Derek Breit's interactive path map Web page that uses Google maps. Maps like the one for the Washington, DC region can be created from Derek Breit's Web site. These maps use the path updated by Steve Preston on Dec. 30, but as noted above, he updated the path with some more recent observations on Jan. 12, and that moved the path 9 km farther south. The maps will be updated in a few days to use the Jan. 12th path. On the 4 maps below, showing the occultation path across the USA along with major highways and cities, the green line is the central line (100% chance for an occultation); the blue lines are the predicted limits (northern and southern limits; 50% chance for an occultation); the red lines are the 1-sigma limits (16% chance for an occultation); and the gray lines are the 2-sigma limits (2% chance for an occultation). These are also in the Power Point file mentioned above. Eastern Time Zone, Delmarva to Ohio Central Time Zone, Indiana to Kansas Mountain Time Zone, Colorado to Utah Pacific Time Zone, Nevada to California On the map below, the blue line is the predicted northern limit (50% chance for an occultation); the red line is the 1-sigma northern limit (northern limit in case of a 1-sigma path shift to the north, 16% chance for an occultation); and the gray line is the northern limit in case of a 1-sigma path shift to the south, with an 83% chance for an occultation). Washington, DC/northern Virginia region WEATHER FORECAST A 3rd (22h prognosis) forecast is now available; I recommend that you go directly to the Web link below to get the maps. The new forecast is very similar to the 2nd (34h prognosis) one, with the cloud cover just a little worse in northwestern & northcentral California, and a little better in northern Virginia. Sorry, I don't have time to update the Power Point file, so it still has the 34h prognosis. We now have the 2nd maps (34h prognosis) of the Canadian weather forecast for astronomy. They show that it will be rather cloudy from Iowa to West Virginia (but mostly clear in w. Indiana and most southern parts of the path west of Cincinnati), and in northwestern Utah (Great Salt Lake area), and also now mostly cloudy in the northern Sacramento Valley of Calif., but mostly clear in the other parts of the path where many observers plan to try to observe. Although it will be cold, especially in the eastern part of the path (about 15 deg. F. in central Virginia), fortunately the forecast now is for less wind, only light to moderate wind at the time in most of Virginia (but now, somewhat stronger winds are forecast from Illinois to Nebraska). For most other areas, the wind should be light. I've taken the relevant 34h prognosis (for 10h UT of Jan. 26) maps and put them in this Power Point file (0.8 megabytes). With this forecast, I plan to follow my "Plan A" to observe from sites near US 301 roughly between Richmond and Dahlgren, VA. OBSERVING IN COLD WEATHER Observers are strongly advised to read this article on cold-weather observing by Guy Nason; his winter observing experiences in Ontario can help us "southerners" not used to this Arctic blast that we are getting. His article includes a wind-chill chart here. Those using Go-To telescopes need to protect the hand paddle from the cold (chemical non-flammable hand warmers taped to them are suggested), and hand warmers can also be helpful to protect batteries and electronics. SATELLITES OF (372) PALMA? Over 100 asteroids are now known to have satellites, but Palma is not one of them. However, observers throughout the USA have a chance to see an occultation by a possible small satellite of Palma, so even observers far from the predicted path are encouraged to watch for a possible event. In November, observers in Japan managed to time an occultation of a 9th-mag. star by the asteroid (22) Kalliope as well as by its satellite Linus from several stations; details are here. So if you can watch 32 Lyncis for about a 5- minute period centered on its time of closest approach for your location, you might see the star blink out briefly by a satellite of Palma. SKY CHARTS FOR LOCATING 32 LYNCIS There are a few thousand stars in the sky that are brighter than 32 Lyncis, so it takes some care to locate it. I strongly recommend that you practice locating the star during a night before the occultation, or if the weather prevents this, at least try to find it during the evening before the event. The star is above the horizon all night, low in the east at sunset and nearly overhead at midnight. I've created some full-sky charts to help novice observers find the target star. There are charts made for six locations; pick the location nearest to yours. These are "bare" charts, that have only Jupiter (for those in the East) and Saturn, and the target star circled. I've annotated the charts for Richmond, VA, and for Redding, CA, with one that shows the area of the 3 detailed charts described below; one that shows only the third one that I recommend to be the main one to use; and then one that labels the major constellations, nearly all of the first-magnitude (the brightest) stars, and the fainter stars needed to find the target star. The target star is not too difficult to find with binoculars once you've located the pair of stars iota and kappa Ursae Majoris (labelled "D" on the charts), which are about halfway between the bowl of the Big Dipper, and Castor and Pollux, the bright pair of stars parallel to the horizon that are prominent in the western sky at the time of the event. In the labelled chart, I show how to star-hop from the bowl of the Big Dipper to 3rd-magnitude stars southeast of the bowl; if you are not too close to a bright street light, you should be able to see these without binoculars (that is, with naked eye, or glasses or contact lens, if you need those for distance vision). Once you have found the "D" pair, you can then use the #3 detailed chart described below to find the target star with binoculars or the finder scope of a telescope. Full-sky charts with 32 Lyncis circled and the local time of the occultation given; otherwise, except for Saturn and (on some charts) Jupiter, they are unlabelled and do not show the areas of the detailed charts: Richmond, VA, 4:44 am EST Indianapolis, IN, 4:44 am EST Omaha, NE, 3:45 am CST Cheyenne, WY, 2:46 am MST Salt Lake City, UT, 2:46 am MST Redding, CA, 1:47 am PST For labelling, and for versions that show the area of the detailed charts, consult the charts in the Power Point file for the location closest to you below: Richmond, VA annotated charts in Power Point file Redding, CA annotated charts in Power Point file Detailed sky charts showing stars to 9th magnitude, the view that can be seen from a dark location with a good pair of binoculars or a good finder scope on a telescope, are in this Power Point file. These charts were adopted from the Herald-Bobroff Astro Atlas. In the Power Point file, there are 3 charts, with the 3rd (northern) chart copied in the 4th "slide" of the file, and annotations added showing how I recommend finding the target star from the "D" pair (iota & kappa Ursae Majoris). These charts just have north at the top; they are not oriented the way you will see the pattern of stars in the sky. So you should turn the charts to help match the view in the sky; the annotated full-sky charts will help show you how to turn the detailed chart. Also, once you find Talitha and the slightly fainter star of the pair, kappa Ursae Majoris (also marked "D" on the 4th slide), you can use their orientation as seen in your binoculars or finder scope to match the chart. Then follow the arrows on that chart, moving south to find first a small triangle of stars, then the star marked "35". Then continue south but jogging to the left to find relatively bright 10 Ursae Majoris (marked "E"), and then on to "G" (SAO 61254). Then move west (right) at a right angle from the "E" to "G" line, using the pattern of stars to reach the diagonal line of a few stars marked "H". Then just continue in that direction to the pair of stars marked 32 and 33. These are 32 and 33 Lyncis; 33 is the slightly brighter star that is closer to "H". The other, slightly fainter, star is the one you should watch, 32 Lyncis, the one that may be occulted by the asteroid Palma, or by a satellite of Palma, depending on where you observe. Another way to find the star might be to just go north from the Beehive cluster, which is flanked by two 4th-magntitude stars, gamma and delta Cancri (also known as Ascellus Borealis and Ascellus Australis, respectively). Then use the Herald-Bobroff chart #1. Almost 10 degrees north of the Beehive is the 4th-mag. star iota Cancri, marked "I" on H.B. chart #1 and on the annotated versions of the Calif. and Virginia full sky charts. If you continue directly north from iota Cancri another 10 degrees, you'll pass over a little "mess" of stars about halfway, and then come close to the diagonal line of stars marked "H" on the annotated H.B. chart #4. Then the 32 & 33 Lyncis pair of stars is just to the west (right) of that diagonal line "H". More detailed information about this occultation can be found at Steve Preston's Web site. I have put the USA path map, and the finder charts of different scales, from Steve Preston's Web site in this Power Point file, which may be easier to view and print for some. PLANNED COVERAGE AND PREDICTED TIMES FOR HUNDREDS OF LOCATIONS If you plan to observe the occultation from within or near the predicted path, within the "1-sigma" line 25 km north of the predicted northern limit to the similar line 25 km south of the predicted southern limit, please let me know your plans to observe the event, reporting your planned location and timing method, especially if you have the means to time the occultation to an accuracy of a few tenths of a second or better. Several amateur astronomers plan to travel into the path with portable telescopes to observe the occultation and they want to select locations that don't duplicate observations from fixed observatories or by those who plan to just observe from their backyard. To help coordinate this effort, we have a Web site where there is an extensive list of cities and stations giving the distance of each location north or south (-) of the predicted central line, the % probability that an occultation will occur there, and the predicted time of the occultation to the nearest tenth of a minute. The time is given in Universal Time (Greenwich Mean Time), which is 9h for all observers; this is 4 am Eastern Standard Time, 3 am Central Standard Time, 2 am Mountain Standard Time, and 1 am Pacific Standard Time. In Hawaii, although no occultation is predicted to occur in the main eight islands, the closest approach hour is 11 pm Hawaiian Standard Time of January 28. Also given are the altitudes of the star and Sun at the time of the occultation, but the event will occur at high altitude above the horizon, in a dark sky with no twilight, for all observers in the U.S.A. In Hawaii, the first quarter Moon will be low in the west at the time, but in the rest of the U.S.A., the event occurs after moonset. Here is a shortened version of the full list giving known stations from which observations are planned; please examine it if you plan to observe, and let me know of any corrections or additions that should be made. This is the second version of this list, with 3 Midwestern observers added (sorry I left them off before); I've shifted a few a little; see the file for details. The new list also shows that the observers in California and Nevada will probably be clouded out, so their coverage can't be counted on. PUBLICITY AND REGIONAL COORDINATORS NEEDED I encourage you to spread word of this event, encouraging friends to watch it from their homes. With the charts and information provided here, the general public can participate. Amateur astronomers who live in the path might submit articles to the science editors of local newspapers and inform other news media. Anyone with a very rudimentary knowledge of the sky, that many learn from scouts, planetaria, or introductory astronomy courses, and a pair of binoculars, can contribute to this effort to learn about an asteroid. The detail of the shape of Palma that we will be able to determine from the observations is proportional to the number of locations from which the occultation is observed, so the more, the better. The same goes for the search for possible satellites of Palma. In January 1991, about 5000 Chinese watched for an occultation of the bright star Alhena (in the constellation Gemini) by the smaller asteroid (381) Myrrha, and 4 of them actually saw it (the predictions were not as accurate then as they are now). We probably won't get that many to watch the Palma occultation, but maybe we can approach the previous record for an occultion by an asteroid - in May 1983, the occultation of the 4th-magnitude star 1 Vulpeculae was timed from 130 locations across the southern U.S.A. and northern Mexico. Besides publicizing the event, we need help from those with shortwave receivers to record WWV time signals at 5 and 10 megahertz along with a strong local AM or FM radio station. This will create a "master tape" that can be used to determine the time of any syllable in the AM or FM broadcast, so that broadcast can be used by others in the area to time the occultation. If you, or a radio ham friend, can do this, let me know and I'll add a list of radio stations here. I plan to do this with WTOP, a strong FM station at 103.5 that covers the Washington, DC area well. Strong clear- channel AM radio stations cover a much larger area and are preferred. Especially, it would be most useful if someone could record WLS from Chicago at 890, that station can be received just about everywhere within the path from the Rockies to the Appalachians. If large numbers of observations are made, we'll need the help of local and regional coordinators to collect reports from observers, determine the coordinates of their observing locations, and file complete reports (see below). TIMES FOR PRE-POINTING TELESCOPES FOR REMOTE STATIONS Offset times and distances for stars with declinations similar to 32 Lyncis', for pre-pointing telescopes for remote stations, are given at the end of the station list on Derek Breit's Web site described in the "planned coverage and predicted times" section above. I wrote a small computer program that reads this list, and the time of the occultation at a given place (or longitude area), and calculates the actual Universal and local times for the pre- pointings. The resulting list for Virginia (near I-95, valid from Washington, DC to Richmond, and for about 40 miles to the east and west) is here and a similar one for near I-5 in northern California is here. I can provide similar lists for other locations/longitudes upon request. REPORTING OBSERVATIONS For reporting observations, even if the star is monitored and no occultation is seen, you should use the new report forms that you can get here and click on "Templates for Report Forms". Completed reports should be sent to reports@asteroidoccultation.com and copied to Jan Manek at jan.manek@worldonline.cz . If you have any difficulty completing one of these forms, just report your observation in an e-mail message to me with whether or not you had an occultation (called a positive or negative observation, respectively); your location (try to specify it to an accuracy of at least 200 ft.; a street address usually suffices for this); any timings of the occultation, if you had one; the approximate start and end time of your observation; and the times of any interruptions in your observations, if any, due to clouds or any other cause. After 20h UT (3 pm EST) I will not be able to update this Web site again. I'll be reachable at my home e-mail below until at least 21h UT (4 pm EST), but shortly after that I'll leave home and likely no longer able to receive e-mail there (I will take my laptop to use in case I need to check the cloud cover, but I won't do that unless really necessary). I can receive e-mail at my office e-mail address below on my Blackberry, but will be checking it only intermittently as I travel and set up my stations. Good luck with your observations! David Dunham, 2007 Jan. 25, 20h UT home dunham@starpower.net 301-474-4722 cell 301-526-5590 office david.dunham@jhuapl.edu 240-228-5609