Occultation of 16 Piscium by (7) Iris, Fri. am, May 5, 2006
Most of the northeastern U.S.A. is in the wide path for this best asteroidal occultation in the U.S.A. since 1983
Although low altitude and twilight pose challenges for many, the target star is 8 deg. from Venus
AND there will be a good occultation of a 10.0-mag. star by (152) Atala across the DC region Sat. night with very good weather forecast
Updated: 2006 May 4, 7:45 pm EDT
We need your help to observe the best asteroidal occultation ever predicted for the northeastern USA, and potentially the best in the USA since the 1 Vulpeculae/Pallas event in the southern USA in 1983. This is the occultation of 5.8-mag. 16 Piscium, in the Circlet of Pisces, by the 200-km S-class asteroid (7) Iris early Friday morning, May 5. Although it looks like many will be clouded out for the Iris occultation, conditions will be much better for Sat. night's occultation by (152) Atala; read the first information about it here. In any case, please let me know if you plan to try to observe this good occultation, either from a fixed site or with portable equipment, so that we can optimize location of several mobile observers for this bright event, targeting them to parts of the asteroid that won't be covered by fixed-site observers. A comprehensive list of stations listed by distance in km from the central line is on Derek Breit's Web site. It is especially useful since it gives the altitudes of the star and the Sun for each station, important since the star will be relatively low in the east with twilight being some factor in most areas. More about the station list is below. In central Penn., central Maryland, and central New York, and places farther west to Ohio and eastern Kentucky, the event might be seen with binoculars, if it is clear low in the east. But small telescopes (& larger ones if you have them) are recommended, especially to give higher magnification to see the star longer into the twilight. THE PATH The occultation will occur within half a minute of 9:02.0 UT (5:02 am EDT) for all locations; you only need to observe for a two- minute period starting at 9:01.0 UT (5:01.0 am EDT). Twilight will be too strong to see the event from the Canadian Maritime Provinces, and probably also from Maine. It might be seen at very low altitude as far west as Illinois and Missouri, but it's hard to locate a rising star so low, and more practically I think Indiana and western Kentucky will be as far west as the occultation might really be seen. The path is very wide, projected by the low altitude into a much larger area than the asteroid width. The southern limit crosses southernmost W. Va.; central Virginia (near Charlottesville and Fredericksburg); near Waldorf & Easton, MD; central Delaware; and southernmost N.J. The northern limit passes over central Indiana (n. of Indianapolis), n. Ohio (Cleveland), just s. of Erie, Penn.; over Syracuse, NY; and northern Vermont & New Hampshire. The limits have a 1-sigma uncertainty of about 25 miles, so areas north and south of these lines could have an occultation, and observers at least out to the 2-sigma limits have some reasonable chance and are encouraged to observe. The central line passes over southern Ohio, s.w. to n.e. Penn. (just n. of Harrisburg & n. of Allentown), s. New York (near Newburgh), n.w. Conn., and over Worcester & just n. of Boston, Mass., but the probability of an occultation is greater than 90% for distances up to 100 miles from the center, greater than 96% for distances up to 80 miles, and 100% for distances up to 60 miles from center, so there's no huge advantage in going to the exact center; it's much better to have observers spread evenly across the path for measuring Iris' size and shape. Derek Breit's Web site given above also has a good map of the wide path showing major cities and highways; besides the central line, it shows the northern and southern limits, and those limits in case of a very possible 1-sigma path shift away from the central line. THE STAR AND THE OCCULTATION The spectral type F5 star is at J2000 R.A. 23h 36m 23.2s, Dec. +02 deg. 06' 08", in the Circlet of Pisces. The star is 16 Piscium = ZC 3482 = SAO 128281 = HIP 116495. The star may be a close double with separation of about 0.01" (about a tenth of Iris' angular size of 0.11"). The star will be about 8 deg. west- northwest of Venus and will be about 1.2 deg. west and a little north of 4.5-mag. lambda Piscium (the southeastern star of the Circlet). To help identify the field, if it's dark enough, 9.0- mag. SAO 128273 is 8' east and a little south of 16, and 8.4-mag. SAO 128268 is about 15' east-north-east of 16 Piscium. Detailed finder charts can be found on Steve Preston's Web site, but I have trouble now printing those maps directly from my Web browser; only a small part of them print. I have put them in a Power Point file that allows you to view and print the whole charts. If an occultation occurs, there will be a 4.4-mag. drop to the 10.2-mag. of the asteroid lasting 5 seconds for a central event. The observations might reveal the star to be a close double, in which case, the disappearance and/or reappearance will occur in steps. The 52% sunlit waxing Moon will have set. The best area for astronomical conditions is in central Maryland - Washington, DC, where the altitude of the star will be 15 deg. above the eastern horizon with the Sun 12 deg. below it, so the sky around the target will not be too bright there. Farther west, the star will be lower, twilight will not be an issue, but you need to find the star at lower altitude as it's rising. It might be effective to pre-point your telescope to a brighter star at the same declination and altitude earlier in the night; I'll try to figure that out and distribute this evening. For observers east of central Maryland and central Pennsylvania, the target star will rise higher, but twilight will increasingly interfere by the time of the occultation; in New England, especialy eastern Massachusetts, the twilight will be very bright and higher magnifications are recommended to try to see the target at the time of the occultation. Observers in those areas will need to locate the target 20 to 30 minutes before the occultation (even earlier in New England) and follow it to the occultation, most easily with a well polar-aligned clock drive. Another way is to prepoint your telescope at 5th-mag. 5 Piscium at 8:34.4 UT (4:34.4 am EDT) and then 16 Piscium will be less than 2' south of where 5 Piscium was at 9:02.0 UT (5:02.0 am EDT), the time of the occultation for many observers (you can adjust by + or - 0.1 or 0.2 min. depending on the predicted time for your location in the station list below). If you observe visually, it would be better to just get on 16 Piscium and follow it since if you center on 5 Piscium, the twilight might be bright enough to make it difficult to recognize and find 16 Piscium by the time it enters your field of view. WEATHER (and my plans) The third (21 hours in advance) Astro Meteo forecast (Clear Sky Clock uses it; the next, and last before the event, forcast will be available just after midnight) for the Iris occultation shows thin clouds/partly cloudy over much of the wide path, with especially areas farther west cloudier (overcast across s. Illinois, and most of Indiana, Ohio, Kentucky, Maryland, W. Va., e. Mass., and much of Virginia). Links to these forecast maps are below. Predicted cloud cover Transparency both in a Power Point file The clearest areas are New Hampshire (except the s.e. corner) and Vermont (where twilight will be very strong) and New York except for scattered thin cloud over the southernmost parts. Smaller mostly clear areas include western Conn. & western Mass., northeastern Penn., and the Atlantic coast of New Jersey. Intermediate cloudiness, still hard to predict now, will be in other areas such as n.w. & south-central Penn., central Virginia, Delaware, and western & northern New Jersey. See below for links to the forecast maps. The forecast is poor, but not hopeless, for the Washington, DC region. To increase chances of getting some observations from the southern part of the path, I plan to try to obtain observations from two or three stations in southeastern New Jersey, but I will make a final decision based on looking at the IR satellite loop before leaving home late this evening, and consulting with the National Weather Service forecasters, and might even contact them by cell phone to change plans at branch points during my drive. STATION LIST AND COORDINATION OF COVERAGE A list of dozens of cities and stations within 3 sigma of the path is at Derek Breit's Web site. From his station list, arranged by distance from the predicted central line, you can see the predicted time of the occultation for your location, as well as the altitudes of the star and Sun, and the probability for an occultation by Iris. You can use your Web browser "find" function to find your name or city in the list. If your station is not in the list, send either your coordinates or the postal address of your observing location to me at dunham@starpower.net and to Derek Breit at breit_ideas@hotmail.com . With this, you can see the event time and circumstances at your location, and we can know that you'll try the event to help plan our coverage. A few of us will be mobile and want to fill in gaps of the fixed-sites coverage; we want to avoid the duplications and near-duplications that we had at the recent Turandot occultation. Mobile observers can be given a distance from the central line to aim for, and they can input that distance in the "offset" box on Derek Breit's interactive google maps site to view the path, and their offset line, in great detail. Below is a list of observers who have said they will try the event; if I missed you, please let me know so I can add you in a future update. After the distance in km from the predicted central line, the codes are F = fixed site, M = mobile site, w = site likely to be clouded out, and [blank] = may observe but no response yet, can't count on it, but try not to exactly duplicate (if your site is a [blank], it would be helpful if you could observe, and even better if you could let us know that you will try). This list is edited down from the much more comprehensive list that's on Derek Breit's Web site with URL given in an earlier message. I may make minor changes to this list to distribute by e-mail shortly before I leave home to obseve the event. Steve Preston's 04/03/06 update Occultation of 16 Psc = HIP 116495 by 7 Iris on 2006 May 5 Distance from center of occultation path - in km Proba- Location Longitude Latitude U.T. Alt Alt km bility o ' o ' h m o o 309 2% ** Northern limit plus 2-sigma, event unlikely but possible ** 289 F 6% Tonawanda NY Bill Watson - 78 54.2 43 0.2 9 2.2 13 -11 263 16% Rochster NY RIT Obs.M.Richmond - 77 39.9 43 4.5 9 2.2 14 -10 265 F 15% Fairfax VT Lawrence Garrett - 72 59.8 44 39.9 9 2.3 17 -6 263 16% ** Northern limit plus 1-sigma, occultation quite possible ** 241 F 30% NEWARK NY BRADLEY TIMERSON - 77 7.1 43 0.3 9 2.2 14 -10 218 50% *** Northern limit *** 209 M 57% MillVilg PA MackeyHillCem.J.Bak - 79 57.4 41 51.2 9 2.1 12 -12 203 63% Sherrill NY Kevin Wigell - 75 36.7 43 4.3 9 2.2 15 -9 169 F 86% n.e. Ithaca, NY CornellHartung - 76 23.1 42 27.5 9 2.2 15 -10 168 86% Quensbry NY MeropeObJohnCordial - 73 36.8 43 22.6 9 2.2 17 -7 161 F 89% Lyme NH Donald Cooke - 72 10.9 43 49.0 9 2.3 17 -6 152 93% Big Flat NY Tony Cecce - 76 55.2 42 7.9 9 2.1 14 -10 150 ?100% Grove City PA Paul Maley mobile 9 2.1 12 -13 138 w 96% Greenfield IN Rob Walker - 85 41.5 39 52.0 9 2.0 8 -17 84 100% SARVER PA HOLTZ~JOHN W. - 79 48.8 40 37.6 9 2.1 12 -13 75 100% Pittsbrg PA Zhu,Persngr,Faust - 80 1.3 40 29.0 9 2.1 12 -13 69 100% VALENCIA PA HONKUS~EDWARD S- 80 5.7 40 24.4 9 2.0 12 -13 67 w100% Indiana PA Coles~Ken - 79 9.9 40 37.3 9 2.1 13 -12 63 100% Fleetville PA Keystone Obs - 75 40.7 41 35.8 9 2.1 15 -10 43 w100% Londonderry NH E.Burkinshaw- 71 21.9 42 52.4 9 2.2 18 -6 37 100% Millvill PA Mike Sheppard - 76 30.1 41 5.1 9 2.1 15 -10 22 100% ATMBostn MA s. of club house - 71 29.7 42 36.5 9 2.2 18 -6 22 100% WALLACEO MA RICK BINZEL - 71 29.1 42 36.6 9 2.2 18 -6 12w?100% Littletn MA Mike Mattei video - 71 28.5 42 30.4 9 2.2 18 -6 10 100% N Granby CT SCOTT TRACY - 72 51.5 41 59.6 9 2.2 17 -8 7 w100% Concord, MA MiddlesexSchOb - 71 22.0 42 29.9 9 2.2 18 -6 4 w100% Bedford MA Alan MacRobert vid. - 71 18.7 42 29.5 9 2.2 18 -6 0 100% **** Centre Line **** 0 w100% Somerset PA Blaine Roelke - 79 17.2 39 56.0 9 2.0 13 -13 -5 F100% Jim Thorpe PA Tom Bash - 75 41.3 40 54.8 9 2.1 16 -10 -7 100% Sudbury MO Dennis DiCicco - 71 23.4 42 21.0 9 2.2 18 -6 -8 100% BELMONT MA SILVIS~GEORGE - 71 11.0 42 24.6 9 2.2 18 -6 -11 100% Belmont MA Gary Seronik - 71 11.2 42 23.2 9 2.2 18 -6 -15 100% Garrison NY Frank Suits - 73 55.0 41 23.1 9 2.1 17 -9 -20 F100% Brooklin MA Clay Center Obs. - 71 8.2 42 18.5 9 2.2 19 -6 -22 100% South Boston, MA Haldun Menali - 71 2.0 42 19.7 9 2.2 19 -6 -27 F100% GLASTONB CT PHILIP L. DOMBROWSK - 72 34.8 41 43.6 9 2.2 18 -8 -36 100% Harrisburg PA - 76 53.0 40 15.7 9 2.1 15 -11 -43 100% Chapaqua NY Robert Davidson - 73 46.1 41 9.6 9 2.1 17 -9 -47 100% Lewisbry PA AST.SOC.OF HARRSBRG - 76 53.7 40 8.9 9 2.1 15 -11 -48 100% Allentwn PA S.Mt,Deterline,etc - 75 27.9 40 33.9 9 2.1 16 -10 -54 100% STAMFORD CT FAIRFIELD CTY.A.S. - 73 33.0 41 7.4 9 2.1 17 -9 -68 100% Douglsvl PA Peter DetterlineObs - 75 42.0 40 18.1 9 2.1 16 -10 -75 100% Cranford NJ SperryOb AAI Clark - 74 19.4 40 40.0 9 2.1 17 -9 -75 100% Central Park, NYC C. Ridgway - 73 57.9 40 47.0 9 2.1 17 -9 -80 100% NEW YORK NY VELIZ~CLAUDIO - 73 58.7 40 43.8 9 2.1 17 -9 -81 w100% Narvon PA Dick Sauder - 75 56.3 40 6.4 9 2.1 15 -11 -84 100% Stonngtn CT USCG Academy Obs. - 71 53.1 41 24.2 9 2.2 18 -7 -86 100% Harlington, NJ Robert Vanderbei - 74 39.3 40 27.1 9 2.1 16 -10 -106 F 99% Holtsvil NY Frank Melillo - 73 2.2 40 47.3 9 2.1 18 -8 -109 99% Marston MD Obs.,Curt Roelle - 77 4.8 39 30.3 9 2.0 15 -12 -118 M 99% Springfield, PA Don D'Egidio, - 75 21.0 39 55.8 9 2.1 16 -10 -118 99% Harwich MA Jim Carlson CCodAS - 70 11.6 41 40.7 9 2.2 19 -6 -121 98% STEPHENS CITY VA BROOKS~JOHN - 78 11.7 39 5.2 9 2.0 14 -13 -122 F 98% Chatham MA Kegan Berner 9 2.2 19 -6 -125 98% MontCuba DE0 Mt.CubaObs.,DE A.S - 75 38.0 39 47.1 9 2.1 16 -11 -127 M 97% NJ David Dunham mobile 9 2.1 16 -10 -141 w 95% Dayton MD Gary Frishkorn - 76 59.6 39 13.9 9 2.0 15 -12 -142 95% Baltimor MD BAS BlmbObs Tolea - 76 37.4 39 19.9 9 2.0 15 -11 -147 94% Gaithersburg, MD Jim Vail - 77 12.1 39 6.9 9 2.0 15 -12 -148 w 94% Essex MD Dale Lehman, Guzman - 76 28.2 39 19.2 9 2.0 15 -11 -149 94% Whiting NJ Arcturus Ob P.Gitto - 74 22.7 39 56.7 9 2.1 17 -10 -151 93% Columbia, MD Don Gardner - 76 50.4 39 10.8 9 2.0 15 -12 -153 M 93% NJ David Dunham remote 9 2.1 16 -10 -155 w 92% Silver Spring MD Scott Wilson 9 2.0 15 -12 -165 Mw88% New Cut Rd, MD Sedlak mobile - 76 40.5 39 6.1 9 2.0 15 -12 -165 88% Bethesda MD John Wetmore - 77 6.5 38 58.7 9 2.0 15 -12 -167 w 87% Vienna VA 2003_428J. Guerber - 77 16.4 38 55.1 9 2.0 15 -12 -167 87% ColegPrk MD UMD Ob.,E. Warner - 76 57.4 39 0.1 9 2.0 15 -12 -169 w 86% GORF16IN Be Wayne H. Warren Jr. - 76 49.6 39 1.3 9 2.0 15 -12 -173 84% WASHNGTN DC MASON~BRIAN U.S.N.O - 77 4.1 38 55.3 9 2.0 15 -12 -174 w 84% Fairfax VA Vince Sempronio - 77 13.8 38 51.8 9 2.0 15 -12 -179 81% Woodmore MD Chuck Quintero - 76 47.9 38 56.4 9 2.0 15 -12 -181 M 81% NJ David Dunham remote 9 2.1 16 -10 -190 w 74% Culpeper VA Bob Oldham 9 2.0 15 -13 -218 50% *** Southern limit *** -221 w 47% Hughesvl MD MICHAEL CAPOBIANCO - 76 49.2 38 32.8 9 2.0 15 -12 -249 w 25% FincastleVA John Goss RVAS - 79 58.2 37 28.4 9 1.9 13 -15 -263 16% ** Southern limit plus 1-sigma, occultation quite possible ** __________________________________________________ David Dunham, IOTA 2006 May 4, 7:45 pm EDT phones home 301-474-4722; office 240-228-5609; cell 301-526-5590 Home (IOTA) e-mail dunham@starpower.net