Spectacular Pleiades Occultation Sat. pm, April 1, in e. North America
The thin crescent Moon, only 16% sunlit, facilitates the view
This is the eastern U.S.A.'s best Pleiades passage since 1969
Spectacular dark-limb grazes of Celaeno, Maia, and Taygeta visible from parts of the Detroit, New York City, Washington (DC), and Statesboro (Georgia) areas
Updated: 2006 March 31
Early Saturday evening, April 1st, the thin crescent Moon, 19% sunlit, will be passing through the Pleiades star cluster. It will be an interesting spectacle for anyone with binoculars to see and thus could be used, with proper publicity, to generate interest in astronomy in our region, as well as other parts of the eastern U.S.A. and eastern Canada. Anyone with a camcorder could even obtain scientifically useful recordings of the numerous occultations that will occur. Predictions of the total occultations of the brighter stars for hundreds of cities and towns are on the main IOTA Web site. Both the Web Master of that site, and I will be out of town from Friday March 24 to March 31 (when I'll be back) for the total solar eclipse on March 29. So from now until the passage, those needing total occultation predictions computed for their location can obtain them upon request (send coordinates to at least 1' accuracy, or the street address of the observing site) to Derek Breit, e-mail address breit_ideas@hotmail.com . There will be several opportunities to observe grazing occultations within paths about a mile wide at the northern limits of the regions of visibility of these occultations. In these narrow zones, the star will appear to move along a tangent line to the Moon's disk, and will disappear and reappear several times among the mountains and craters on the dark side of the Moon near the cusp at the Moon's north pole. Later I will add a Moon figure showing the view. If you are north of the graze zone, the Moon will narrowly miss the star and there will be no occultation. If you are south of it, the star will disappear on the dark side, then several minutes later will reappear on the bright side of the Moon. You can get some idea of what a grazing occultation of a bright star looks like by looking at this video of the first part of a grazing occultation of Aldebaran recorded in Poland a few years ago. They also obtained a video of the exciting last part of the graze. The star remained hidden behind the Moon for about a minute between the two sequences. Simple methods for timing and/or video recording occultations are described here. The best weather for the Pleiades passage is expected to be in the southern Mid-Atlantic region, from southern Virginia to central South Carolina and westward to central Tennessee. The 36h forecast cloud cover maps for the start of the Pleiades passage (0h UT April 2 or 7 pm EST April 1) are below: eastern U.S.A. eastern Canada Both are in this Word file But after midnight tonight (after 5h UT April 1), you can get updated forecast maps at the Astro Meteo Web site. Charlie Ridgway has posted path overlays on interactive maps that use google maps to give very detailed map and aerial vies of graze zones as well as of asteroidal occultations. His general Web site has links to the map sites and describes how to "navigate" the maps to get very detailed views of regions of interest. There is a link specifically for the 2006 Pleiades grazes; scroll down to April for the April 1/2 Pleiades passage. This includes an overview map showing the three best grazes currently posted, including a static low- resolution view in a Word file and also for the individual grazes as follows: 5.5-mag. Celaeno, Detroit to New York City 4.3-mag. Taygeta, n. Mississippi to Charleston, SC 3.9-mag. Maia, n. Illinois to s. Delaware ALCYONE, THE BRIGHTEST PEIAD I haven't mentioned in previous messages the southern- limit grazing occultation of Alcyone, the brightest Pleiad (mag. 2.9), that passes over the Miami area, and also near Houston and other areas to the west (to the Tucson area in twilight or daylight). The star is bright enough that events involving it might be timed fairly easily with even small telescopes, even though it will be on the sunlit limb of the 16% waning crescent Moon. Although not as spectacular as the binoculars Maia and Taygeta dark-limb grazes, the Alcyone event should be very interesting, and valuable for charting the southern lunar mountains. Detailed path maps for this graze & information is on Charlie Ridgway's Web site. Go to his main Pleiades page; it now has the paths for over a dozen more grazing occultations of stars down to magnitude 7.5 that cross the eastern U.S.A. and southeastern Canada. At the top of the April 1/2 Pleiades grazes section, he has spaces for three overview maps for eastern Canada & Maine; northeastern U.S.A.; and southern U.S.A., but there are no links there yet; by the time you read this, he may have added them and then you can open them to see which graze paths are near your location. All of these are northern-limit grazes that will occur on the Moon's dark limb except for the grazes of Merope, Alcyone, Atlas, and Pleione, which are southern-limit grazes on the Moon's sunlit side. The bright-limb events involving Alcyone can be observed with small telescopes, and that star is even bright enough that it can be observed in daylight, so the path is extended west in the area from southern Arizona to central Texas where it will occur before sunset. The bright-limb grazes of Merope, Atlas, and especially Pleione will be quite difficult to observe. Ridgway has the offsets set properly to show the multiple events graze zone between the two gray lines. Actually, these offsets do vary along the paths some; they were determined for the New York City area for Celaeno; for the Washington, DC area for Maia; and for Statesboro, GA for Taygeta. The longitudes for the graze zone offsets for the other grazes on Ridgway's Web site are as follows: West Star Longitude deg. Electra - ZC 537 52 SAO 76152 75 Merope - ZC 545 95 Alcyone - ZC 552 95 22 Tau - ZC 543 81 ZC 546 64 ZC 548 83 ZC 553 70 ZC 557 73 Atlas - ZC 560 78 Pleione - ZC 561 79 ZC 562 73 SAO 76234 76 SAO 76249 63 SAO 76259 76 Currently, the last 6 events are listed but have no links to the detailed interactive maps on Ridgway's site, but by the time you read this, he probably will have added them. The graze zone offsets will not change significantly for at least 2 deg. of longitude from the above locations, and for most, the valid range is much larger. Later I will describe here how the offsets change at other locations along the path so that you can manually enter the offsets for your area to get the best map of your local graze zone. SPECTACULAR MAIA GRAZE IN WASHINGTON, DC REGION For the Washington, DC region, if it is clear, I will be recording WTOP along with GPS & WWV time signals so that anyone else in the region can record WTOP at 1500 AM or 103.5 FM for an accurate time base. Extensive predictions of the total occultations are at the bottom part of the Mid-Atlantic occultations & expeditions page. Many maps and other details of the graze, including some preliminary ideas on where to observe the graze with possibly very large expeditions is here. SPECTACULAR TAYGETA GRAZE IN GEORGIA & S. SOUTH CAROLINA Becky Lowder and Harold Povenmire are leading a large expedition to observe the Taygeta graze from Statesboro, Georgia. The path also crosses Birmingham, AL and Macon, GA, but the latest forecasts indicate that it will be quite cloudy there. If clouds threaten Statesboro, Povenmire and some others might go farther east, perhaps observing from just s. of Hardeeville, SC where the path crosses I-95 & US 17. More information is here. David Dunham phones cell 301-526-5590; office 240-228-5609; home 301-474-4722