Occultation (Eclipse) of the star TYC 0728-01958-1 by (663) Gerlinde on Oct. 29 - New 2007 Oct. 26, 21h UT
The star in northwestern Orion can be seen with 4-inch telescopes
Help us measure the size and shape of the asteroid (663) Gerlinde Monday morning; clear skies forecast, e. Idaho to cen. Calif.
We need your help to observe the next relatively bright (visible with 4-inch telescopes) North American asteroidal occultation, of a 9.5-mag. star north of Betelgeuse by the 101-km asteroid (663) Gerlinde that will occur Monday morning, Oct. 29th, the 50th anniversary of my beta Capricorni near-graze observation in southern California that ignited my quest to compute and observe these events. I'm returning to that region to measure Gerlinde's size and shape, and hope that you might be able to help. The path, extending from the north-northeast to south-southwest, passes over southern Saskatchewan (Regina near center) at 12:59 UT (in bright twilight, Sun alt. -7 deg., but with the high star altitude and ability to find the star in darkness half an hour before, that should not be a problem; the event occurs in darker conditions farther southwest, especially in central Calif., where astronomical twilight will just be starting). At 13:00 UT (7:00 am MDT), the path crosses central Montana; at 13:01, eastern and south-central Idaho, and n.e. Nevada; at 13:02 UT (6:02 am PDT), central Nevada to the Sierras east of Fresno with Bishop, Calif. near center; and at 13:03 UT (6:03 am PDT), over the San Joaquin Valley with Fresno just outside the n.w. limit and Bakersfield just outside the s.e. limit (with the prediction uncertainties, either city has a good chance for an occultation) and over the central coast, with San Luis Obispo and Santa Maria in the path. Accuweather is forecasting clear skies along the path from eastern Idaho to the California coast; apparently, light winds will likely prevent marine clouds in the coastal areas. Unfortunately, mostly cloudy skies are forecast for s. Saskatchewan. The target star is in northeast Orion, 7 deg. north of Betelgeuse and 2.4 deg. west of 4th-mag. nu Orionis, at J2000 RA 5h 57m 51.1s, Dec. +14 deg. 48' 12". The target is also 1.4 deg. east-northeast of 5th-mag. 137 Tauri and only 7' north of an 8th-mag. star that is shown on Steve Preston's charts (see below) but surprizingly is not in either the SAO or PPM catalogs. The target star is also the northeastern component of a wide (separation about 1') double, with the other component slightly fainter. For path maps and detailed finder charts of different scales, see Steve Preston's Web page. A central occultation is expected to last 13s with a 5-mag. drop. The gibbous (84% sunlit) Moon will be 15 deg. away (near El Nath), so it will brighten the background view in finder scopes, but should pose little problem, especially for telescopic views, either visually or with video. The event will occur high (almost 60 deg.) above the southwestern horizon. PLANNING COVERAGE TO DETERMINE GERLINDE'S SIZE & SHAPE Let me know your plans to observe this occultation; a few already have, indicated in the list below. If the weather is good, as the current forecast says it will be, I hope to set up 3 stations across the path near I-5 but I want to select locations that will avoid your line. Consult Derek Breit's global Web site (see below for the link) for station lists to see the possible coverage of the event, to get the distance from the central line predicted for your location (as well as the predicted UT, probability for an occultation, and circumstances) as well as the interactive Google Map of the event to plot offset lines for mobile site selection or determine distances from the central line for observers who might not be in the station list. Below I give some information about local circumstances for known stations within and near the path from which observations might be made. NOTE MOST OF THE STATIONS BELOW ARE ONLY POTENTIAL OBSERVING SITES; JUST BECAUSE THERE ARE MANY IS NOT AN EXCUSE FOR YOU NOT TO OBSERVE, SINCE IN FACT NO OBSERVATIONS WILL BE MADE FROM MOST OF THESE LOCATIONS. PLEASE ATTEMPT AN OBSERVATION IF YOU ARE WITHIN THE 2-SIGMA LIMITS; AN OCCULTATION COULD OCCUR AT YOUR LOCATION AND YOU COULD DETERMINE A VALUABLE CHORD FOR DETERMINING Gerlinde'S SIZE AND SHAPE. Between the "distance from center" and "Prob." columns, I give codes for those who have said they will try to observe this occultation, V for fixed video observer; * for fixed visual observer; M for mobile video observer; and ? for unknown, can't now count on an observation being made there, but it would be very useful if an observation could be attempted there. Occultation of TYC 0728-01958-1 by 663 Gerlinde on 2007 Oct 29 [Prediction of 2007 Oct 23.1] Distance (+ north of center, - south of center) from center, Universal Sun in Prob. Time Alt km % Observer and/or location h m s o 200 0 ** Northern limit plus 3-Sigma ** 196 0 Hollistr CA David Baumgartner 13 3 4 -17 190 ? 0 Dayton CA Red Sumner 13 2 31 -16 187 0 Sleaford Observatory, SK- Huziak 12 59 40 -9 179 ? 1 MIRA Obs CA MIRA Oliver Observ. 13 3 11 -17 151 2 ** Northern limit plus 2-Sigma ** 129 6 Butte MT 13 0 56 -12 101 16 ** Northern limit plus 1-Sigma ** 93 20 Madera CA Ken Simmons 13 2 58 -16 80 M 28 D. Dunham remote near I5 65 ? 39 Fresno CA Clarence Funk 13 2 58 -16 62 41 Atascdro CA Lee Combs 13 3 16 -16 60 ? 42 Cuesta College, S.L.O., Calif. 13 3 18 -16 52 48 *** Northern limit *** 40 ? 56 Genet Obs - Russ Genet 13 3 17 -16 38 58 Moose Jaw SK 12 59 53 -8 34 60 Arroyo Grande, CA Jamie Foster 13 3 20 -16 23 M 70 D. Dunham remote near I5 (if problems, just 1 6 M 70 D. Dunham remote near I5 station at +14) 0 71 **** Centre Line **** -1 71 Tulare CA TAA Ken Copeland 13 3 3 -15 -6 70 Regina, SK Bergbush,Beech 12 59 50 -8 -10 70 Regina, SK Vance Petriew 12 59 50 -7 -11 V 69 Bishop CA Stoffaire~Jim 13 2 46 -15 -22 66 CarrizoP CA Nolthenius mobile 13 3 17 -16 -22 66 3 Rivers CA Ken Fields 13 2 58 -15 -42 V 55 SPRINGVILLE CA SANFORD~JOHN 13 3 0 -15 -42 * 55 Springvi Ca 2003_718Ron Royer 13 3 1 -15 -47 ? 52 Springvi CA 99 3_3Billie Chandl 13 3 2 -15 -52 48 *** Southern limit *** -67 37 E E Barnard Obs Allan Morton 13 1 14 -11 -70 M 35 D. Dunham mobile -74 32 SantaBarbara CA 13 3 24 -15 -76 30 EastBakrsfieldCA Oliver2~Don 13 3 10 -15 -87 23 Pocatello ID 13 1 26 -11 -90 22 Carpenteria CA Ed Edwards 10 13 3 24 -15 -90 22 668 San Emigdio Peak 13 3 17 -15 -101 ? 16 LockwoodValleyCA EDBERG~STEVE 13 3 18 -15 -101 16 ** Southern limit plus 1-Sigma ** -107 13 665 Wallis Observatory 13 3 17 -15 -114 ? 10 Ventura CA V. A. S. 13 3 24 -15 -114 ? 10 669 Ojai 13 3 21 -15 -134 ? 5 Fillmore CA DreamWeaverObCMorri 13 3 21 -15 -137 4 670 Camarillo 13 3 24 -15 -140 ? 4 CamarilloCA Gary Goodman 13 3 24 -15 -144 3 VALENCIA CA MEDEARIS~JERRY 13 3 18 -15 -148 ? 3 NewburyP CA Robert J. Stine 13 3 24 -15 -149 2 666 Moorpark College Observator 13 3 22 -15 -151 2 ** Southern limit plus 2-Sigma ** -153 ? 2 Castaic CA ANET~FRANK 13 3 19 -15 -158 2 Simi Valley CA Veronica~Jim 13 3 22 -15 -162 ? 1 Ridgcrst CA CARROLL L. EVANS JR 13 3 2 -14 -163 1 G70 Francisquito Observatory, L 13 3 19 -15 -164 1 Castaic CA S.ClaritaV D.Engles 13 3 19 -15 -172 1 Northridge CA Jim Miller 13 3 21 -15 -181 0 Lancastr CA AVAC Stephen Mathis 13 3 15 -14 -186 0 453 Edwards Raven Observatory 13 3 10 -14 -196 0 Burbank CA George Willis 13 3 21 -14 -200 0 ** Southern limit plus 3-Sigma ** I'll be flying to Burbank late Sat. Oct. 27. On Sunday, if the weather forecast remains good, early Sunday afternoon I'd like to stop somewhere between Burbank and Castaic to get internet access for receiving and distributing any late updates for the station coverage; any help from observers in that area with this would be greatly appreciated. I will not be able to update this Web page; later updates will be distributed by e-mail. _________ For all 2007 "Preston" events worldwide, very detailed maps are on Derek Breit's interactive Web page that links to the very detailed maps and satellite imagery of maps.google.com with overlays of the occultation paths and their 1-sigma uncertainty zones. Also on that Web site are station lists giving local circumstances, for many observer stations, now including all of the MPC observatories and other sites in an expanded list of stations. It gives the predicted time of the event, distance from the updated central line, probability that an occultation will occur there, and altitudes of the star and the Sun. If your station is not in that list, please let me and Derek, breit_ideas@hotmail.com , know so that you can be added to future lists. Also on this site are lists of stars, mostly brighter than the target star, that can be used before the event to pre-point stationary (non-tracking) telescopes. Much information about observing occultations of all types is in "Chasing the Shadow: The IOTA Occultation Observer's Manual" available for free here. Much information about asteroidal occultations in general is on Brad Timerson's asteroidal occultation page, with info. about reporting observations, etc. North American observers are encouraged to find updated asteroidal occultation paths near them by consulting the maps and associated tables on Derek Breit's N. American paths Web page. I also recommend software called Occult Watcher that you can install on your computer. With it, you input your position and it searches Steve Preston's predition Web site, informing you of all asteroidal occultations in your region during the next 4-5 weeks, giving probabilities and other details. Whenever a path is updated, the software lets you know. It also has provision for you to specify your observing intentions, and these are displayed along with those of other observers to help plan the overall coverage for the event. Hristo Pavlov in Sydney, Australia wrote this program; you can get it here. Note that the path predictions are not perfect, they can shift due to mainly now to stellar proper motion errors that are increasing with time from the 1991 mean epoch of the Hipparcos satellite observations. So observers not just within the predicted path, but also north and south of it, at least within the 1-sigma uncertainty zones shown by the dashed lines on the maps on Steve Preston's Web site, should also watch for, and preferably be prepared to record and/or time, an occultation. Sometimes (less often, but not impossible) shifts of 2-sigma can and do occur, so observers a little outside the 1-sigma lines are also encouraged to observe. Theoretically, the actual path will be within the 1-sigma lines 67% of the time, and within the 2-sigma lines 95% of the time. ________________________________________________ David Dunham, 2007 Oct. 26, 21h UT 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 .