Eclipse (called "Occultation") of the star TYC 0748-01711-1 by the asteroid (903) Nealley Mon. am, Nov. 19 - New 2007 Nov. 16, 19h UT
The path for this 9.8-mag. occultation crosses North America from Cape Cod to New York City, central Maryland, cen. Tenn., cen. Texas, to s. Baja
Mostly clear skies are probable at least for the Maryland region
We need your help to cover the path and its uncertainty zone; I plan to set up 3 mobile stations in Maryland
If you live near the predicted path of the occultation that passes over Cape Cod & Long Island at 10:07 UT = 5:07 am EST, over New York City, New Jersey, Philadelphia, central Maryland at 10:08 UT; at 10:09 UT W. Va., at 10:11 UT (4:11 am CST) central Tenn. (Nashville at n. limit), at 10:12 UT s.e. Arkansas, at 10:13 UT Shreveport (Louisiana), Texas (event possible at 10:14 UT from Waco, Austin, & San Antonio), & n.w. Mexico (at 10:18 UT = 3:18 am MST) La Paz, Baja Calif. at n. limit, please help us measure the size and shape of the asteroid (903) Nealley when it will occult a 9.8-mag. star 10 deg. west of Procyon Monday morning, November 19. We need your help to cover the path to obtain the best coverage for this event. Please let me know if you can try to observe this event so that mobile observers can be positioned at the best places to avoid duplication of your observation. Since the occultation will occur at 5:08 am EST in s.e. Penn. and Maryland, and at 5:09 am in northern Virginia, times when most observers are just getting up to go to work, just go to bed and get up about an hour earlier than usual, so you can set up your telescope and find the target star; then just after the occultation, quickly take down your equipment, eat breakfast, and go to work with little disruption of your usual schedule. Use whatever timing equipment you have (stopwatch or wrist watch with stopwatch mode, tape or digital audio recorder, etc.) to time the occultation as well as you can; visual observations are fine for this event, with a predicted central duration of 12s. For timing tips, click here. For those in the Washington, DC region, we will record WTOP at 103.5 FM along with WWV time signals; WTOP can then be used as your time reference using a car or any FM radio. If you have two stopwatches, or one with split timing, start one at the WTOP tone marking 5 am, and stop it when the star disappears (if it does disappear at your location), at the same time starting the other timer to just time the duration of the occultation (stopping the second one at the reappearance). If you have an astronomical CCD imager, you should take a long exposure during the minute or so centered on the expected time of the occultation for your location, turning off the clock drive during the exposure; the occultation can then be timed by measuring the break in the star's trail; click here for more about this. The star is in northeastern Monoceros; the easiest way to locate it is to find one of two 6th-mag. stars, set your scope on one of them, then turn off your clock drive for a few minutes, and the target star will then be in your field of view, just north of where the 6th-mag. star was. The target star, TYC 0748-01711-1, is at J2000 RA 6h 59m 54.3s, Dec +8 deg. 24' 28", about 7 deg. west of 3rd-mag. beta Canis Minoris and approximately in line with a line drawn south-southeast extending from the bright 2nd-mag. star gamma Geminorum (Alhena) to 4th-mag. xi Gem about 1.5 times the distance between those two stars to the target area, which is shown in 3 annotated star charts in this Power Point file, which also has maps showing the predicted path in your area. The star charts show the two 6th-mag. stars, labelled A and B, listed below. Just center on them; the target star will then appear the indicated distance in arc minutes (') north of where the 6th-mag. star was in the amount of time indicated (try to time it so the target star will be in your field of view a minute before the event, then turn your clock drive back on, or just manually adjust to keep on the target). to target offset Star mag R.A.(J2000)Dec time distance h m d ' m s ' A = SAO 114556 5.8 6 52.8 +8 23 7 4 +1.6 B = SAO 114626 6.3 6 55.6 +8 19 4 19 +5.0 More information and a few more finder charts (not annotated) of different scales are on Steve Preston's Web page for the event. The detailed path maps, generated from D. Breit's interactive Google maps site, in the Power Point file above are also individually given below. northeastern USA s. New England to DC Maryland & vicinity more detailed view W. Virginia & surroundings DC to cen. Tennessee cen. Tenn. to Texas The medium range Accuweather forecast is good for our area, with only scattered cirrus forecast, little or no wind, temp. about 32 deg. F. (dress warmly), and relative humidity 73% (so expect some dew or frost, use dew shields (one made of paper taped to the front end of your scope will be o.k. if you don't have a manufactured shield) for refractors and Schmidt-Cass. telescopes. The location of the predicted path, expected to be 64 km wide, is uncertain by almost a full path-width "1-sigma" (one standard deviation), so an occultation is not guaranteed anywhere; the chances are greatest at the predicted central line, 40%, but are only slightly less, 35%, at the limits, and drop to 14%, still a reasonable chance, at the 1-sigma limits (94 km from center), which encompass virtually all of the Washington, DC region, so all in the area are encouraged to observe. To be sure, observers at least to the 2-sigma limits (156 km from center) are also encouraged to watch from convenient home locations. Remember that the interactive detailed maps for this and other events, and extensive lists of stations (should include yours, if its within 3-sigma of the path center) and also lists of stars for pre-pointing telescopes, are on Derek Breit's Web site; scoll down to the line of links for the event at its central time, 19 Nov 9:56 UT. Some other Asteroidal Occultations (mostly Mid-Atlantic events) 2007 Planet or dur. Ap. Date Day EST Star Mag Asteroid dmag s in. Location Nov 18 Sun 1:44 SAO 39874 9.3 Wombat 6.1 1 3 NJ,PA,swNY Nov 18 Sun 2:57 1 Arietis 5.8 2000 AD142 11.4 1 1 VA,sWV Nov 19 Mon 5:08 TYC07481711 9.8 Nealley 5.2 12 4 NJ,sePA,MD,nVA Nov 20 Tue 1:54 TYC02451257 10.1 Amalia 5.4 3 4 n GA, s S.Car. Nov 23 Fri 2:18 2UC37297689 11.9 Ausonia 0.5 18 8 NJ,nMD,sPA,nWV Nov 23 Fri 21:04 TYC00870420 10.8 Erimomisaki 3.0 2 6 NJ,PA,neOhio Nov 24 Sat 19:10 2UC44450138 11.0 Chenqian 3.5 3 6 wNY,wPA,eOH,KY Nov 27 Tue 5:58 2UC39628815 10.9 Lameia 3.2 4 6 VA,sWV,sOhio Nov 29 Thu 0:50 TYC12300772 10.5 Miyazaki 3.9 2 5 NYC,nNJ,nePA Dec 3 Mon 0:26 TYC19000667 9.0 Ruvuma 6.6 4 2 sS.Car.,sGA Dec 5 Wed 3:58 TYC12860663 10.8 Imperatrix 4.5 3 6 NJ,PA,nOhio Dec 5 Wed 17:50 2UC42014653 11.9 Dembowska 0.1 12 8 sNJ,DE,sMD,VA Dec 8 Sat 5:39 TYC49350372 11.1 Aurelia 2.8 5 7 GA,s.S.Car. Dec 9 Sun 18:48 TYC63650480 11.5 Cornelia 4.3 2 8 seSC,e.N.Car. Dec 20 Thu 0:09 TYC24160772 9.4 Lamberta 3.3 9 2 s.VA,sWV,KY The Nov. 18th Wombat path extends from northern New Jersey to southern British Columbia, while the occultation about an hour later of 1 Arietis (HIP 8544) by the 10-km asteroid (16184) 2000 AD142 will be visible from a narrow path extending from Virginia to Los Angeles. But the 1-sigma uncertainty zones for these two events are twenty or more times the path widths, much worse than for the Monday morning Nealley event, so the chances for seeing an occultation are small, not warranting travel to observe them (that is, try them only from convenient home or nearby observatory locations). The chances for obtaining the most useful size/shape information are much better for the Nealley occultation, so we recommend concentrating on it; the weather forecast is poor for the Washington, DC region for the Sunday morning occultations. I will distribute a station list for the Nealley occultation this evening; in the meantime, you can see it on Derek Breit's Web page given above. A shortened version of the station list, which can be used to find the exact time and circumstances for your location, and the probability for an occultation, will be used for planning coverage for the event once I hear from observers about their plans. David Dunham, 2007 Nov. 16, 2 pm EST Phones home 301-474-4722; office 240-228-5609; cell 301-526-5590 office e-mail david.dunham@jhuapl.edu with Blackberry for mobile use home e-mail: dunham@starpower.net .