Good Regulus "eclipse" & graze in s. USA, Sat. am Nov. 3
This was the last 1st-magnitude graze in the USA until at least June 2009
All known expeditions, in n.e. Utah, s.w. Missouri, s. cen. Tenn., Atlanta (actually, Conyers, GA) and w. of Savannah, GA, were successful
Updated: 2007 Nov. 5, 17h UT
The shadow swept from west to east. Derek Breit (Martinez, Calif.) and Salvador Aguirre (near Hermosillo, Sonora, Mexico) video taped the total occultation. All known expeditions for the northern-limit graze whose narrow path crossed the USA from southern Orgeon to just s. of Savannah, GA (where the Sun's altitude at central graze was +3 deg.) were successful, as noted briefly below: n.e. Utah, Patrick Wiggins (paw@wirelessbeehive.com) led an expedition with at least 3 stations, from at least 2 of which video recordings were obtained. s.w. Missouri, Bob Sandy (bobgraze@sbcglobal.net) led an expedition with at least 3 stations, from at least one of which a video recording was obtained. near Pulaski, s. cen. Tenn., Scott Degenhardt (scottyd@charter.net) successfully video recorded the graze; unfortunately, nobody joined him to see the spectacle. From Conyers, a suburb of Atlanta, GA, Mike Kazmierczak (mike2007@beow.org) observed the graze. From sites just n. of Lanier, GA, Wayne Warren (Greenbelt, MD), Bob Rose (Savannah), and I recorded the graze from 3 stations, two of them with video (one was a remote station that I ran using a Supercircuits PC33C color camera). I tried to run two other stations, one remote and the other attended, but they used the sensitive PC164C cameras, and for both of them, the image was saturated and all contrast lost, with nothing obtained, when the sky brightened at sunrise. I thought the camera's automatic gain would decrease the overall brightness enough to prevent saturation, but that didn't happen; those cameras just can't be used for daytime events. _________________________ The prediction information below was last updated Nov. 2 at 19h UT. You have a chance to see the bright 1.4-mag. star Regulus (ZC 1487) flash off and on repeatedly among mountains and craters near the north pole on the bright side of the 34% sunlit Moon between 11:00 and 12:00 UT Nov. 3 from southern Oregon to eastern Georgia; see the path on the map on p. 75 of the Jan. issue of Sky and Telescope. The first Astro Meteo (48h prognosis) forecast maps show good conditions with clear skies along the whole path across the USA except for a chance of clouds near I-25 in s.e. Wyoming. Help us measure variations in the diameter of the Sun Saturday morning, Nov. 3rd, by mapping the topography along the northern edge of the Moon. This information helps us analyze observations of Baily's beads that have been recorded during several total and annular solar eclipses observed during the last few decades. The information can be obtained by observing a grazing eclipse (called "occultation" by astronomers) of Regulus from locations within a mile or two of its northern limit. This is the last chance for observers in the USA to see a graze of a 1st-magnitude star until at least June 2009. The path also passes north of Ogden, UT; just south of Laramie and Cheyenne, WY; near Emporia, KS; over s. Missouri, w. Tenn.,and n.e. Alabama; and over the southern suburbs of Atlanta, GA (just before sunrise there). Southwest of the mile-wide graze zone, a total occultation, can be seen, from the southern USA and Mexico before sunrise, and then in daylight from Central America, the Caribbean, and northern South America. The event is described on page 70 of the November issue of Sky and Telescope. That article has good maps of the event and a good moonview, but Harold Povenmire pointed out that the article says that the event will occur Sunday morning, when actually it will be Saturday morning, and Joe Rao notes that the Moon will be crescent, not gibbous as the article states, although it correctly shows the lunar crescent in the moonview. Predictions of the occultation are also given for several dozen cities on a page of the main IOTA Web site, including a map showing the region of visibility, here. The graze line is path #208 on p. 151 of the RASC Observer's Handbook for 2007 (those maps, as well as tabular details of the graze, are also here). The graze will last one to three minutes. Some more information is given in a link to a Web page by Joe Rao here). The 3rd Astro Meteo (24h prognosis) forecast still shows clear skies over the path across the whole USA, except for a patch of clouds over s.e. Wyoming. You can zoom in on the path in great detail using the "ZC 1487 (Regulus)" link on Brad Timerson's interactive graze map site here. The pre-set offset lines, +5.0 and -5.0 km, are too wide to define the narrow graze zone for this northern-limit event. Different values for the offsets can be specified by the user to define the graze zone, by consulting the predicted profile closest to their longitude, with profiles for 7 longitudes being given. In general, -2.0 km can be used for the southern edge of the zone, while the northern edge of the zone would be +1.0 for long. 90 deg. W.; +0.5 for other locations east of the Rockies; 0 for long. 120; and -0.4 for long. 114 W. But in addition, a correction needs to be made for the observer's height above sea level. Multiply the height above sea level (converted to km; km = value in feet times 0.0003048) by 0.26 to get the km south (negative) that the path should be shifted south. For example, to specify the graze range for long. 114 deg. for an observer at 5000 feet elevation above sea level, the sea level graze range would be -0.4 and -2.0. Then for the 5000 feet = 1.52 km above sea level, the path shifts an additional 0.4 km (= 2.1 x 1.52) south, so the offsets in this case would be -0.8 and -2.4. Brad Timerson (btimerson@rochester.rr.com) can provide further help; he set up the Web site. To determine when to observe, note your longitude; if you don't know it, you can click on the center of the interactive map described above and the lat. and long. of the point you click on is displayed at the bottom of the map. Then click on "Times" on Timerson's site, and you'll see a list of coordinates in the graze path, including the Universal Times of central graze. Subtract 3 minutes from the central graze time for the time to start observing, and observe for 6 minutes from then, to be sure to include all the grazing contacts. Expeditions for this event are being led by Robert Sandy in western Missouri (bobgraze@sbcglobal.net), by Patrick Wiggins in Utah (paw@wirelessbeehive.com), and by Scott Degenhardt (scottyd@charter.net) in south-central Tenn., near Pulaski west of I-65 a little north of the Alabama border. Mike Kazmierczak (mike2007@beow.org) might try the graze in the Atlanta, GA area, and Roger Venable (rjvmd@hughes.net) might try it in Georgia farther east. We plan to observe the graze from sites near US 280 north of Lanier, Georgia, about 25 miles west of Savannah; observers in Georgia are welcome to join this effort. We will meet at 6:45 am EDT on the east side of Little Creek Road just south of where it runs into US 280 north of Lanier; it is marked on the 2nd, 4th, 5th, and 6th slides of this Power Point file. Let me know if you might be able to join our effort. An alternate area could be along US 17 southwest of Savannah, but that highway may be busy, not very suitable for setting up telescopes, and there are no alternatives nearby in that swampy area. Then due to the path crossing part of Fort Stewart, there are no other accessible sites until those near Lanier. We will be leaving the Washington, DC area about 4 pm EDT Friday Nov. 2; after that, I'll probably NOT be reachable via my home e-mail of dunham@starpower.net. Unfortunately, I've lost my cell phone, so the only way to reach me will be via Wayne Warren's cell phone, 301-518-5754, since he will be with me during this trip except for 45 min. or so before the graze, when we go to our different stations. Several maps showing the path over parts of Tenn., Alabama, and Georgia are in the Power Point file mentioned above. The individual maps, in case you have trouble with the Power Point file, are below, but they don't have the meeting place near Lanier, Ga. indicated like the versions of the maps in the Power Point file. The graze zone is between the two gray lines; no occultation is likely at the northern limit line (the green line) since this is a relatively low area of the Moon n. cen. Tenn. & n. cen. Alabama; Degenhardt's expedition will be near Pulaski, Tenn., near the upper left corner. The path passes near Hazel Green, Ala., only about 20 mi. n. of Huntsville. path over Atlanta, Georgia path over central Georgia path over eastern Georgia path over Lanier, GA area (map) path over Lanier, GA area (aerial photo) Lanier, GA meeting place detailed view path over US 17, poor backup site s.w. of Savannah Brad Timerson has posted predicted profiles for selected longitudes along the graze path in the USA. The profiles include appropriate previously-observed graze data points that define the actual profile more accurately than the smooth "Watts" profile. The graze will be an interesting spectacle to watch, but even better if you can time or video tape it; for information about timing, click here or read the IOTA online observing manual. One sidereal month earlier, another graze of Regulus early in October was very successfully observed from England, Belgium, and Germany. _____________________________ 2007 November 5, 17h UT David Dunham, dunham@starpower.net, 301-474-4722 Office david.dunham@jhuapl.edu phone 240-228-5609 After 4 pm EDT Nov. 2, use only Wayne Warren's cell phone, 301-518-5754, since I lost mine (but found it again about an hour ago, so now you can use it, 301-526-5590).