Bright Asteroidal Occultation, s. USA, Oct. 13 am
We need YOUR observations to determine the shape of 1585 Union
New: 2003 October 10We need your help to cover the predicted path and its uncertainty zone for the occultation of 7.1-mag. SAO 117102 by the 50-km asteroid (1585) Union that is expected to be visible along a path across the southern USA Columbus Day morning, Monday, October 13, at 9:13 UT (5:13 am EDT, 4:13 am CDT, 3:13 am MDT, and 2:13 am MST in Ariz.). This event is potentially nearly as good as the highly successful Varsavia occultation in British Columbia and the Pacific States last July, possibly being observable with a good pair of binocalars (although small telescopes are recommended). Video observations especially are encouraged (the star is easily bright enough to record with a PC23C camera on a 6-inch or larger telescope) since the predicted central duration is only 1.8 seconds (with a huge 7.7-mag. drop, but that could be less if the star is a close double). Let me know if you'll plan to observe from your home location (send coordinates if I don't already have them), or if you are mobile to help fill in gaps of the fixed-site coverage. The path of the occultation crosses southeastern Arizona (but at rather low altitude, around 7 deg., rising in the east); Texas from just south of El Paso to Georgetown-Temple and Huntsville; southern Louisiana (Baton Rouge is in the path); and northern Florida (Gainesville and Palm Coast near the center). The uncertainty is now a full path-width (expected to decrease some with new astrometric observations that are planned the next couple of days), so an occultation is very possible from Tucson, AZ; Las Cruces, NM; El Paso, Austin, and Houston, TX; New Orleans, LA; Mobile, AL; the whole Florida panhandle, including Jacksonville, and as far south as Daytona Beach. Some detailed path maps, showing the predicted path enclosed with black lines and the 1-sigma limits for a possible occultation enclosed with parallel red lines, can be found on Steve Preston's Web site. The star is a few degrees south of Hydra's head at J2000 RA 8h 46m 20.1s, Dec. +0 deg. 38' 49". Finder charts (a wide-field one; and 5-deg. and 2-deg. charts) can be found at the above Web site. Accuweather is forecasting mostly clear skies, only about 30% cirrus, around the time of the event from Austin, Texas to Gainesville, Florida. Thicker, lower clouds are forecast along the Florida east coast and over much of western Texas. I am planning to lead an expedition from Maryland/DC area leaving by van late Saturday morning, Oct. 11, hopefully by 10 am. We will rest there on Sunday pm before the event, then will drive back after the event (which I hope we can observe from the Gainesville area, but could be farther west if the weather prospects are better to the west), planning to arrive back home late Monday night/early Tues. morning. So far, there are two of us; if you would like to join the effort, helping further with the driving, let me know. I will have one or two extra video systems to lend to local observers for use with their telescopes. Rui Goncalves in Portugal obtained the first astrometric observations of the current apparition a couple of nights ago and they essentially confirmed the earlier path, shifting it only a little to the north. More observations were obtained this morning at JPL's Table Mountain Observatory in California; those observations will permit an improved prediction for the path that should be available on Steve Preston's Web site later today. I'll distribute that when I can, but won't be able to while I'm travelling (but should be able to sometime Sunday while I'm in Florida). Also then I hope to distribute a list of stations sorted by distance from the latest updated central line prediction, similar to those for some previous events, but it will not be possible to post that on this Web site. It might be posted on one of the other Web sites, such as the main IOTA site. David Dunham