Large Asteroid (52) Europa Occ'n Sat. Dec. 3 am, s.w. USA
Thousands of telescopes are in this path, including populous parts of California, Arizona, and New Mexico
The very wide path and 8.9-mag. target star make this one of the best asteroidal occultations of 2005 in the USA
Observers in w. Texas might find star an hour before & follow it to the event in bright twilight
First results will be reported at the Small Bodies Educator's Conference that will be held at Jet Propulsion Laboratory over the weekend.
Updated: 2005 Dec. 1
For those who want some general information about asteroidqal occultations, see this Power-Point presentation (5 megabytes). For information about timing occultations, click here with some more good information by Guy Nason here. If you have a 2-inch or larger telescope, we need your help to observe the occultation of 8.9-mag. SAO 139619 = TYC 4974-00584-1 by the 302-km asteroid (52) Europa, one of the ten largest asteroids (NOT the Galilean satellite of Jupiter with the same name), visible Saturday morning Dec. 3rd in a path passing over much of the southwestern USA. Please get up a little earlier than usual this weekend morning to observe this possibly best asteroidal occultation of 2005 in the USA. We are making plans to cover the path as well as we can, with several observers being mobile; please let us know your plans to try to observe this occultation so that one of the mobile observers doesn't waste effort duplicating your chord across the asteroid. For most observers, the occultation will occur at 13:07 UT (5:07 am PST = 6:07 am MST). The predicted northern limit passes over San Pablo Bay north of San Francisco, CA; just north of Las Vegas, NV and Flagstaff, AZ; and south of Albuquerque, NM, while the predicted southern limit passes over Santa Barbara, the San Fernando and San Gabriel Valleys, and Riverside, Calif.; just north of Tucson, AZ; and south of El Paso and near Ft. Davis, Texas. But the limit locations are uncertain by as much as 50 miles (the star is not in the more accurate Hipparcos catalog) so observers throughout the Los Angeles area, or in places to the north like Sacramento and Albuquerque, have a chance for an occultation, and are strongly encouraged to try to observe the target star; their observations will be most valuable for measuring the edges of the shadow. Near the path center are Monterey, Tulare, Ridgecrest, and Needles, Calif.; Prescott, AZ; and Truth or Consequences and Carlsbad, NM. At El Paso, the Sun altitude will be -9 deg., so twilight will be strong enough to cause some problems there, especially seeing fainter stars in finder scopes - observers in eastern Arizona and locations farther east should locate the star half an hour or more before the event while the sky is dark enough to "navigate", then follow the star to the event. That way, even observers in Midland and Lubbock, Texas (where the event will occur at 13:08 UT = 7:08 am CST) might have a chance to observe this occultation, but east of there, I think it will be hopeless, as the target star in Virgo is in the approximate direction of sunrise. For more information about this event, see Steve Preston's Web site. It has detailed finder charts of different scales to easily locate the star. Some fairly detailed maps showing major highways are on that Web site, with even more detailed maps available at Derek Breit's and Charlie Ridgway's Web sites described below. If you can help us observe this occultation, either from your home or observatory, or as a mobile observer, please inform me and Derek Breit (e-mail breit_ideas@hotmail.com ). For coordinating coverage of this occultation, a list of stations sorted by distance in km from the predicted central line, is on D. Breit's Web site You can search for your, or your town's or observatory's, name to see just when the occultation is predicted for your area (that time should be accurate to within 15 seconds or so), the probability for having an occultation there, and the predicted Sun and star altitudes at the time. If your station is not in the list, send me and/or Derek Breit your coordinates, or your street address, and we can add it. Derek will update his Web site with information indicating which distances from the central line (or "chords") will have observers trying to time the occultation. Some observers have already specified their intentions; those at fixed sites are indicated in red in Derek's list, and mobile observers are in green. Let me know your plans, whether you plan to observe from a fixed site or are mobile, needing a line to aim for. During the next nights, I'll distribute an edited down list of stations from Derek Breit's more extensive list including only those who have said that they will try to observe this good event. I hope to try to observe the occultation from multiple sites across the path, probably mostly near I-15 north of Barstow, Calif., but may select a different area, depending on the weather (I'll be flying into Ontario airport, arriving there about 7 pm Friday, but am connecting through Phoenix so I could change to go there instead if the weather forecast is better in Arizona). If any others want to help me with this, let me know. You can see the path superimposed on very detailed maps and satellite imagery on Charlie Ridgway's Web site. For general information about his site, click here, while for the map specifically for the Europa occultation, click here. On this site, you can enter a distance from the central line in km in a special "offset" box (just write over the default value of 1000 given there) and it will plot gray lines at that distance north and south of the central line. Type your distance number (in km) in the box just to the left of the "Plot Offsets" box at the bottom of the map. You need to type a number with no sign, then two gray lines are plotted; zoom in on the gray line northeast of the yellow central line if your distance is + and on the gray line southwest of the central line if your distance is -. You can move the map by grabbing it (left-clicking and holding down) and you can zoom in or out by left-clicking on the scale in the upper left part of the map (+ on that scale means "zoom in" for more detail over a smaller area). You can toggle between "map" (showing town and road names), "satellite" for satellite imagery, and "hybrid" for both together. The target star is in Virgo 11 deg. northwest of Jupiter and 9 deg. northeast of Spica at J2000 RA 13h 54m 58.3s, Dec -05 deg. 43' 55". The target star is only 9' north of 7.8-mag. SAO 139617 that should be visible in all finder telescopes; also, 11' east and a little south of the target star is 8.6-mag. SAO 139610. The spectral class of the target star is B5. If an occultation occurrs, it would last up to 8 seconds with a 3-magnitude drop. The first Astro Meteo forecast (on which Clear Sky Clock is based), to 1 hour before the event, is now available. It generally confirms the earlier Accuweather forecast, showing mostly clear skies across the path in California except south of a line extending approximately from Long Beach to Needles, and also clear over western Texas and s.w. New Mexico. It will be mostly cloudy across Arizona (but the clouds should be thin in the southeast) and in central New Mexico near the Rio Grande. In California, clouds are also predicted to bunch up and linger in the southeastern and southermost San Joaquin Valley, around Bakersfield and the adjacent mountains. You can see the cloud forecast map here and the transparency forecast map here. Observers who have said they will try to observe are indictated below. After the distance in km, w means that chances are good that they will be clouded out; m means mobile observer, f means fixed- site observer. If you are not already on the list, please let us (me at the return e-mail address of this message, and if possible, also Derek Breit at breit_ideas@hotmail.com) know so we can add you; a last update will be distributed early Friday morning by about 6 am PST. Mobile observers should also let us know so we can recommend a distance for you to aim for, and use Charlie Ridgway's Web site given in my last message to find a location; if possible, specify a range of distances within which you would prefer to locate. The list below is based on the much larger list, including hundreds of observers who have not yet indicated if they will try to observe (probably including your station), on D. Breit's Web site. Thursday evening, I will determine a plan for my own remote and attended stations based on the coverage and weather forecast at that time. I am planning to set up the stations in the central part of the path, mostly on the northern side if the weather forecast is good along I-15 east of Barstow (not the case now), but mostly on the southern side if I need to go farther west (probably to Hwy 14/US 395, my current plan). Occultation of TYC 4974-00584-1 by 52 Europa on 2005 Dec 03 After about 0h UT Dec. 2, this list will not be up-to-date; Derek Breit's Web site with link above will then have more recent updates so you should consult it. I'll update the list and distribute it by e-mail this evening, but probably will not have a chance to update this Web site after this posting, until Tuesday next week. Distance from center of occultation path - in km Star Proba- Location Longitude Latitude U.T. Alt Sun km bility o ' o ' h m o o 287 2% ** Northern limit plus 2-sigma ** 231 f 14% Tijeras, NM Becky Ramotows -106 15.6 +34 58.7 13 7.9 31 -10 226 16% ** Northern limit plus 1-sigma ** 200 w 28% Los Lunas, NM Steve Welch -106 45.4 +34 48.3 13 7.9 31 -10 166 f 49% Antioch CA JOHN E. WESTFALL -121 48.7 37 57.6 13 7.6 18 -23 165 50% *** Northern limit *** 163 m 50% DEREK'S MOBILE SITE 154 m 57% WalntCrk CA ROBERT G. SHELTON -122 1.9 37 53.3 13 7.6 18 -23 137 f 68% Pleasntn CA WALTER V. MORGAN -121 52.5 37 41.7 13 7.6 18 -23 117 w 78% Socorro NM Mark Vincent Mobile -106 53.5 34 3.5 13 7.9 31 -10 114 w 80% Magdalena NM Bill Ryan -107 14.3 34 7.0 13 7.9 31 -10 55 m 96% RICHARD NOLTHENIUS Europa -120 49.0 36 42.6 13 7.6 20 -22 48 w 97% Springvl CA John Sanford -118 48.3 36 13.5 13 7.6 21 -20 26 w 99% Haigler AZ Sam Herchak -110 57.9 34 12.7 13 7.8 28 -13 0 99% **** Centre Line **** -50 f 97% Silver City NM NFO -51 m 97% Derald Nye Mobile Europa -117 32.9 35 1.7 13 7.6 23 -19 -55 f 96% LasCrucs NM Bill Stein -106 46.1 32 23.4 13 7.9 32 -9 -62 f 95% LasCrucs NM Rich Richins -106 44.2 32 18.8 13 7.9 32 -9 -63 f 95% LasCrucs NM Robert A. James -106 47.7 32 19.4 13 7.9 32 -9 -79 w 92% Scottsdl AZ Randy Peterson -111 54.7 33 27.8 13 7.7 28 -14 -95 f 87% Ed Morana Mobile Europa -120 41.0 35 17.5 13 7.6 20 -21 -101 w 85% Chandler AZ Michael Collins -111 49.3 33 14.1 13 7.7 28 -14 -123 f 75% Writewod CA Table Mountain Obs. -117 40.9 34 22.9 13 7.6 23 -19 -125 f 74% Wrightwood, CA Karen A. Young -117 38.4 34 21.7 13 7.6 23 -19 -128 f 73% RunningS CA Robert Jones -117 7.9 34 13.1 13 7.6 23 -18 -144 w 63% Maricopa AZ StonehavenOb,S.Dodd -112 8.7 32 55.1 13 7.7 28 -14 -154 f 57% LaCanada CA STEVE EDBERG -118 10.4 34 12.4 13 7.6 23 -19 -154 f 57% ALTADENA CA G.Lyzenga &L. Benne -118 7.7 34 11.9 13 7.6 23 -19 -165 50% *** Southern limit *** -166 w 49% OroVally AZ JIM STAMM -110 57.9 32 25.2 13 7.8 29 -13 -175 w 43% Tucson AZ SabinoCan.Obs.McGah -110 49.1 32 18.0 13 7.8 29 -13 -226 16% ** Southern limit plus 1-sigma ** -254 w 7% Ramona, CA Fred Bruenjes -116 49.3 32 59.6 13 7.6 24 -18 -287 2% ** Southern limit plus 2-sigma ** Coverage just south of the southern limit, where an occultation could occur, is very poor, the two observers there both likely to be clouded out. It would help if observers on the west side of the Los Angeles area, where clear skies are predicted, especially south like Torrance and Palos Verdes, and west to Carpenteria and Ventura, could observe to help fill this void. Note that some observers are "bunched up", such as around Las Cruces, NM; Derald Nye should go a little farther north (since his current plan duplicates, within a km, a fixed site in southern NM) and one of the Las Cruces observers might go mobile (south might be towards higher chance of clear skies?). Steve Edberg in La Canada will have to be mofile since trees block his view at his house, but he will not be able to travel far, just a few km - if possible, he should go north. It would be better if Richard Nolthenius observed from a location 20 km or more farther north to better fill a large gap on the northern side of the path. All day Saturday, Dec. 3, and during the morning, Dec. 4, a Small Bodies Educator's Conference, focusing mostly on space missions to asteroids and comets, will be held at the von Karman auditorium at the Jet Propulsion Laboratory in Pasadena, Californa. I'm scheduled to speak about asteroidal occultations at 9:30 am Sunday. The agenda is here. For more information, contact David Seidel at JPL at David.M.Seidel@jpl.nasa.gov . David Dunham, 2005 Dec. 1, 22h UT e-mail home dunham@starpower.net; office david.dunham@jhuapl.edu