Spectacular mu Arietis graze in Texas TONIGHT (2007 June 12 UT)
New: 2007 June 11, 21h UT
Sorry, except for this Power Point file, I don't have time to create hot links for the URL's mentioned below, you need to cut and paste them into your browser. If you can, please try to observe the spectacular n. limit graze of the 5.7-mag. close triple star mu Arietis (ZC 399) by the 10% sunlit Moon between 9:57 and 10:06 UT tomorrow night (actually early Tues. am, June 12, 4:57-5:06 am CDT. Let me or Rick Frankenberger know if you can join either his expedition s. of San Antonio or mine n.w. of Houston, or if you might try on your own somewhere else. The path, crossing southeastern Texas, northern Louisiana, and northern Mississipii, is path #112 on p. 149 of the RASC Observer's Handbook for 2007 (those maps, as well as tabular details of the graze, are also on my Web site at http://iota.jhuapl.edu/grazemap.htm. For 2-3 min., the bright star will flash on and off in steps as its components are occulted by mountains & craters along the n. edge of the Moon in a km-wide path that passes near Tilden on Route 16 about 50 miles s. of San Antonio, Texas; just n. of Cuero; s. of Weimar and e. of Columbus near I-10; east of Waller near US290 (my expedition n.w. of Houston plans to use sites near there); over Conroe at I-45 n. of Houston; near Goodrich, TX crossing US59; near Natchez (I-49), Winnfield, and just e. of Monroe, Louisiana; near Grenada (I-55) and n.w. of Tupelo, Mississippi (twilight starting to get rather bright there); and over Nashville, Tenn., but with the Sun alt. -4 deg. there, it will be difficult. You can zoom in on the path in great detail using the ZC 399 link on Brad Timerson's graze page at http://www.fingerlakessynthetics.com/occultations/GrazeMaps.html or directly at http://www.fingerlakessynthetics.com/occultations/0610ZC399.htm . For the interactive map, you need to enter different values for the gray offset lines depending on the area you want to map the path, according to the table below (these are distances in km from the northern limit line; they are all south since this is a shallow part of the Moon: upper lower gray gray line line Moon A B Alt. Area -1.0 -2.0 10 Tilden, TX near Route 16 -0.9 -1.9 11 Cuero, TX -0.8 -1.8 12 Columbus, TX near I-10 -0.7 -1.7 13 Waller, TX near US290 -0.6 -1.6 14 Conroe, TX -0.4 -1.4 16 Natchez, LA near I-49 0.0 -1.5 22 n.w. MS Occult doesn't have the right information about the close components. The components are mag. 6.3, 6.8, and 8.3, respectively. The bright pair is only 0.01" apart in PA 188, while the 8.3-mag. 3rd star is 0.2" north of the tight pair. So the graze range shouldn't be modified on account of the duplicity, since the bright pair is so close and the 3rd star's events will occur in the southern half of the graze zone. I'm especially interested in this star because I co-discovered the close duplicity during a s. limit gibbous Moon graze in St. Louis (where I lived then) in Jan. 1969. In August 1973, students from the Univ. of Texas and I (I was at U.T. then) drove to Edinburg in s. Texas to try to observe a n. limit graze of mu Ari. It was cloudy there, so we drove about 100 mi. s.w. along the path into Mexico, setting up along a dirt road where my van got stuck in the mud near the n. end of the graze zone. The probable 3rd component was discovered during that expedition. In late Dec. 1973, we drove to southern Mexico to observe an annular eclipse. On the way back, we stayed with friends in Mexico City, and from there, made a side trip s. to Cuernavaca to observe another n. limit graze of mu Arietis. But either the Mexican maps or the predictions weren't as good in those pre-Hipparcos/pre-GPS days and all but the southernmost observer had a miss. These were all visual observations; now I want to capture a graze of this interesting star on video. Observers within 0.2 or even 0.3 km north of the northern gray line will probably have one, or maybe two, short occultations by the tops of the highest mountains, but they risk getting a miss. Observers up to 1.5 km south of the southern gray line will have a few multiple events at the start and end of a nearly 2-min.-long occultation, but not nearly as many multiple events as observers between the two gray lines are likely to get. The profile on Brad Timerson's Web site is misleading because it is for longitude 75 deg., in daylight far northeast of where the graze can really be seen, and just uses Watts data rather than previously-observed graze data, which are important for this event (the old graze data show that the actual lunar profile is lower than predicted by Watts). In the graze zone, the star will approach the Moon from the bright side, passing over the north cusp a few min. before graze. It will be an interesting spectacle to watch, but even better if you can time or video tape it; for information about timing, see http://iota.jhuapl.edu/timng920.htm or the IOTA online observing manual at http://www.poyntsource.com/IOTAmanual/Preview.htm . A total occultation (for most, just 1 disappearance, usually on the dark side very close to the north cusp, followed generally 10 to 15 min. later by the good dark side reappearance, will be visible from most of the central eastern USA south of the northern limit. The Canadian weather forecast for astronomy (Astro meteo) updated their forecast recently; their 34h prognosis is for mostly clear skies along the path over Texas with average transparency west of Waller and only slightly poorer to the east. Clouds increase rapidly along the path in Louisiana and Mississippi is overcast, but quite clear again in Tennessee. Observers will need to find locations with not too many nearby trees or buildings obstructing the east-northeastern horizon, where the Moon will rise. Fortunately, rather detailed aerial photography showing trees quite well is available in the "satellite" or "hybrid" views of the interactive Web site above. I have used it to select suitable sites north and west of Houston, along mainly unpopulated rural roads with good views over fields in the graze zone. Sometime Monday afternoon, I'll post maps of some of these on my Web site at below. In the meantime, they are described below; you can find them either on your own local maps, Google Earth, other mapping Web sites, or the interactive Web page given above (Timerson's site). A. Sites along Hegar Rd. extending for 0.7 mile north from Waller Tomball Rd (FM 2920), the meeting intersection - try to be there no later than 4 am CDT. To get there, go north for 2.5 miles on Hegar Rd. from its exit from US290 4 miles east of Waller; this is about 30 miles northwest of downtown Houston. B. If the weather makes it better to go farther northeast, there are few useable sites since the area is rather heavily forested. I found two possibilities northeast of Conroe: B1. Along FM 1484 (called Browder-Traylor Rd., at least n. of the graze zone) extending 0.5 mi. n. and s. of its intersection with S William Rd. To get there, go 8 miles e. on Route 105 from I-45 in the middle of Conroe, to FM 1484, which is also 4.5 mi. e. of Route 336 (Loop 336 East); then go about 2.5 mi. n. on FM 1484 from Route 105. B2. Only if B1 doesn't work, it should be possible to observe from an industrial area from sites along Beach Airport Rd. from 0.3 mi. n. of Route 105 to 0.4 mi. s. of it. Beach Airport Rd. intersects Route 105 3 mi. e. of I45 or 1 mi. w. of Loop 336 East. C. If the weather makes it better to go farther southwest, there are good sites near I-10 e. and s. of Columbus, about 60 mi. w. of downtown Houston. C1. Along Lehrmann Rd. extending for 0.7 mi. s. from FM949, whose exit from I-10 is 6 mi. e. of Columbus. Turn n. onto FM949 and go 4 mi. to Lehrmann Rd. C2. Almost as good is along Frelsburg Rd. from 0.7 to 1.4 mi. n.w. of the FM949 exit from I-10. FM949 first goes n.w. from the exit for 0.6 mi., then bends 90 deg. to the n.e.; instead, continue n.w. onto Frelsburg Rd. C3. Along Route 71 from 0.9 to 1.6 mi. s. from its exit from I-10 at Columbus. I could find no good sites s.w. of Columbus and s. of Weimar. The Houston A.S. has an observing site in this area; I found it from its coordinates, it looks like there's a Stonehenge-like circle there. But it's n. of the northern limit so no occulation (a miss) will surely occur there, and there is no reasonable access to sites s. of there, which is rather heavily forrested. Similarly, I found Star Ridge Observatory s. of Weimar, but it is also too far north relative to the path and will have a miss. If it's necessary to go farther west, I will just join Rick Frankenberger's effort near Tilden s. of San Antonio; his phone numbers are 210-681-2276 (home) & 210-834-2276 (cell); his e-mail is rickf@stic.net . Paul Maley was going to try to organize some effort from Houston for this, but I haven't heard from him, and he said that if he returned too late from his current trip, he might have to give it up. I'll be checking how well Astro Meteo forecasts this (Mon.) morning's weather in southeastern Texas, which is supposed to be similar to but slightly worse than that for Tues. am. I will decide about 1 pm CDT, based on what happens later this morning and the new Astro Meteo forecast that will be available then, to decide if I'll procede with my flight, which leaves Baltimore at 7:30 pm EDT and should arrive at Houston Hobby at 9:45 pm. Of course, on Wed. morning there will be the good graze of the Pleaides star Taygeta, but at only 4% sunlit, the Moon/Sun altitude combination won't be as good for it as for mu Arietis. But it is a brighter star, worth a good effort. For it, Accuweather is predicting just scattered clouds at Del Rio and Hamilton, but partly cloudy (& some rain) in Dallas, and quite cloudy at Junction. There are also other Pleiades occultations and grazes that morning, especially a good Maia graze over Salt Lake City; see the RASC Observer's Handbook or http://iota.jhuapl.edu/grazemap.htm . Rick Frankenberger (see above, Tilden expedition, for his contact info.) has made extensive preparations for the Taygeta graze, with much detailed information in a 1.7-megabyte Word file that I can send you on request, and which I'll post on my Web site. 2007 June 11, 6:30 UT David Dunham, dunham@starpower.net, 301-474-4722, cell 301-526-5590 Office david.dunham@jhuapl.edu phone 240-228-5609 _____________________________ From: David Dunham [dunham@starpower.net] Sent: Monday, June 11, 2007 2:30 PM Subject: mu Ari tonight, Taygeta Wed. am, updates The new Astro Meteo forecast is good enough that I still plan to proceed with my plans to fly to Houston to try to observe tomorrow morning's graze of mu Arietis. It shows scattered thin clouds and slightly less transparency east of about Columbus, TX, with clear skies and a little better transparency west to Tilden, but then some decrease in transparency again west of Tilden. But also, the map of relative humidity shows that it is higher west of Columbus than east of there. So I think for now it is best to proceed with two expeditions, mine to east of Waller as described before (Site A), and Rick Frankenberger's to Tilden; with two separate efforts, at least one will hopefully succeed. It looks like it's too warm for "adiabatic cooling" clouds to form, except perhaps farther inland, well northwest away from the path. The surface temp. forecasts are a few deg. above the dew point so hopefully there won't be much ground fog; the Columbus area, near a large river, seems to be wetter and I think may be more prone to ground fog than the Waller area. The Astro Meteo forecast for this morning was rather accurate; there were scattered high clouds at the Houston airports at 10h UT, and automated stations at small airports that seemed to be near Waller and Conroe were clear. The surface reports indicated cloudier skies in San Antonio, Austin, and Waco, but there was no station near Tilden to say what happened there. To get to the A sites from Houston, take US 290 towards the northwest. As you approach the small town of Hockley 4 miles east of Waller, US 290 bends right away from US 290; follow 290 for about 0.4 mile to the Hegar Rd. exit. Go north on Hegar Rd. to the meeting intersection. That is now shown in this Power Point file. Bob Sandy plans to visit the area this evening; if necessary, we might use other roads crossed by the path towards the southwest, so if possible, keep in touch by cell phone. I hope to get a motel room in Waller; hopefully, it will have wifi for sending more messages and checking both the last Astro Meteo forecast, the IR satellite images, and airport surface reports. If not wifi, I can get e-mail sent to my office e-mail, david.dunham@jhuapl.edu on my Blackberry. The heights above sea level are small enough that I did not take that shift, quite insignificant, into account with elevations less than 60m from the Columbus to the Conroe areas. It seems to be about 200m near Tilden. David Dunham, cell 301-526-5590