Three bright asteroidal occultations in N. America, Sept. 14, 15, and 20 UT
With all the interesting high-value but faint occultations coming up, you are also reminded of two bright rank 100 occultations that will occur less than a week from now, and another one a week later. The asteroids are medium-sized, worth travelling to observe, or monitoring from your home to try to obtain a high signal-to-noise (believable) but low probability recording of a brief occultation by a possible moon of these objects. Event details, including small-scale path maps and finder charts of different scales, are on Steve Preston’s asteroidoccultation.com Web site, while Derek Breit’s interactive Google maps at poyntsource.com/New/Google allow you to zoom in on the path and see street views to select mobile sites. With Derek’s Google map, you can enter + and – 10 times the asteroid’s diameter to plot two dark gray lines that bracket the approximate region from which an asteroidal satellite occultation is possible.
There was a fourth bright (mag. 8.7) occultation a few nights ago (Sept. 7) by the largish asteroid (191) Kolga that occurred over central Calif. (Santa Maria near the center, with San Luis Obispo and Visalia at the n. limit and Bakersfield at the s. limit, and over Beatty, NV (n. of Las Vegas), but I was too busy with other projects before that event to send out reminder notice. Nobody signed up for it on OW. Earlier, we had hoped to be in AZ in time to try this event ourselves, but a number of things delayed our departure from MD. Now we expect to arrive at our Fountain Hills, AZ home just a couple of nights before the Camelia occultation.
Sept. 14, 8:25-8:28 UT (3:25am CDT to 2:28 MDT), 8.5-mag. SAO164481 = HIP 106475 by 66-km (217) Eudora
The path passes about 60 miles south of Chicago (but only about 8 deg. alt. there, in azimuth 246 deg., so you’ll need an unobstructed horizon in the west-southwest); about 40 miles n. of St. Louis (alt. 10 deg.; Columbia, MO at n. limit); over Tulsa & Oklahoma City; between Abilene & Midland, Texas; over Big Bend Nat. Park; and then over n.w. Mexico, just missing Cabo San Lucas. The satellite search area includes most of the Midwest, Tornado
Alley (Kansas through Texas), n. Alabama, most of Mississippi, Louisiana, & New Mexico, & n.w. Mexico, including s. Sonora and Baja Calif. sur. The star, spectral type K0, is in n. Capricornus at J2000 RA 21h 33m 54.6s, Dec -12 deg 08’ 16”; its Gaia RUWE is 1.1 (low, good). There should be a strong 4-mag. drop lasting up to 13s for a central occultation. Since the Eudora occultation occurs with the object in the west, you can just acquire it an hour or more beforehand, when its altitude will be higher, and track it to the event. Another idea would be to pre-point to a brighter star at the same declination and let the target drift into the FOV; for the Eudora event, you can do with 6.7-mag. SAO 164388 = ZC 3137 about 2 deg. west of the target star. Aim your scope at ZC 3137 7.5 min. before the occultation, turn off any tracking and clamp the telescope so it doesn’t move, and the target star will be near where ZC 3137 was in your FOV when the event occurs. Bob Sandy plans to observe this occultation from a farm near Big Cabin, OK, south of center; others signed up on OW include Skip Whitehurst with two stations south of Tulsa, and John Moore with one north of the city. The link to Preston’s page for this event is
The link to Breit’s Google map is
Sept. 15, 8:40-8:56 UT (5:40am ADT to 1:56 PDT), 7.2-mag. SAO 75054 = TYC 1757-01963-1 by 74-km (957) Camelia
The path passes over Goose Bay, Labrador, where the Sun alt. is -5 deg., but the bright star should be easy to observe there, 47 deg. above the w.s.w. horizon, opposite the Sun. The path continues southwest across N. America, brushing the northern part of Lake Manicouagan, passing just n. of Timmings, Ont.; passing over western Upper Michigan; passing over Minneapolis-St. Paul; over Sioux Falls, S.D.; over Denver, with Boulder near the n. limit and Castle Rock near the s. limit; over n. Arizona, with the n. limit over Kingman and the s. limit over Ash Fork, Wikieup, and Parker; and over San Diego, with the n. limit near Palm Springs, Temecula and Oceanside, and the s. limit over Chula Vista. The satellite search area includes a wide swath of N. America within 740 km of the above-described path, as far north as Billings, MT; Twin Falls, ID; Reno; Sacramento, and San Francisco; and as far south as Bangor, ME; Rochester, NY; Indianapolis; Oklahoma City; and El Paso.
The star, spectral type G0, is in Aries at J2000 RA 1h 57m 57.6s, Dec +23 deg 36’ 11”; its Gaia RUWE is 1.0 (low, good). A complication of this event, actually making it easy to find the target, is that the star is only 37 arc seconds n.e. of (PA 46deg.) 4.8-mag. lambda Arietis = SAO 75051. This may make this impossible for mighty mini systems that might not resolve the two stars; even other systems, the gain and/or brightness might be adjusted down so that the 7.2-mag. target is evident, and better separated from lambda. You should test your system on the target some night before the event. The target (and lambda) are about 2 deg. east of Hamal. There should be a strong 7-mag. drop lasting up to 15s for a central occultation. Joan and I plan to observe the occultation from a few sites near US 93 between Kingman and Wikieup; you are invited to join our effort, to learn how to make mobile and remote-station observations. Other observers signed up on OW include Vadim Nikitin near Boulder, Paul Maley near center, and Steve Messner hoping to run two stations near the s. limit. The link to Preston’s page for this event is at
and the link to Breit’s Google map is
Sept. 20, 9:11-9:13 UT (3:11am MDT to 5:13am EDT), 7.1-mag. SAO 59869 = HIP 34733 by 135-km (762) Pulcova
The path crosses n. Mexico, with the n. limit over Monterrey and Reynosa, then over southernmost Texas, s.e. Louisiana with the n. limit over New Orleans & Mobile, AL; then n.w. Fla. with Destin at center and Tallahassee at the s. limit; then over s. Georgia with Savannah and Hilton Head Is., SC at the center. But with the high Gaia RUWE, the path could shift more than a path-width north or south. The satellite search area includes a wide swath of N. America, including the USA south of a line from Yuma to Milwaukee, and populous s. Ontario and Quebec s. of a line from n. of Ottawa to Quebec City, and south to Guatemala and e. Cuba.
The star, spectral type F2, is in Gemini at J2000 RA 7h 11m 28.9s, Dec +30 deg 28’ 21”; its Gaia RUWE is 3.5 (high, beware; the actual path can be even more than a whole path-width in error). The target is 15 arc min. north of 4.4-mag. tau Geminorum and 5 deg. west of Castor. There should be a strong 7-mag. drop lasting up to 5s for a central occultation. Currently, NOBODY within the predicted path or the 1-sigma zone has signed up with OW, but Paul Stuart in Houston and Salvador Aguirre in Hermosillo, both well to the north, have signed up for a satellite search. Preston’s link for the event is at
https://www.asteroidoccultation.com/2021_09/0920_762_71240.htm while Breit’s Google map is at http://www.poyntsource.com/New/Google/20210920_71240.HTM .
Pulcova has a known 20-km satellite that is expected to occult the star in a path south of the primary object’s occultation path, but this satellite orbit is poorly known, so an occultation by it could occur even north of the predicted path for the main object.