Since my Feb. 4th prediction, a few new observations have been reported, and these move my updated path about 0.4 path-widths farther south. So now Orlando and Melbourne, FL are near the s. limit at about 6:13.5 UT (1:13 am EST), then over the Fla. panhandle, s.w. GA, & southern AL; Jackson, MS; n.e. LA, s. AR at 6:15 UT, s. & w. OK, Pueblo & Colo. Sprgs., CO (Denver just n. of the n. limit; just after 6:16 UT), Salt Lake City (6:17 UT), & Salem- Eugene, Ore. (Portland near the n. limit) at 6:18 UT. The time is 0.4 min. earlier than my Feb. 4th prediction. This is all about 5.7 path-widths south of the path in my map in the Feb. issue of S&T and 0.7 min. later than times that would be inferred from that map. This prediction is based on Martin Federspiel's calculations; I do not have time to make my own calculations for it. Now that he feels that the path is still rather uncertain, by +/-0.15" or 1.6 path- widths, so observers farther south in Florida and in n. Texas, and farther north in Georgia and s. Washington state still have a chance for an occultation.
The IOTA finder chart for the event is now available here, along with those for other events coming up in the next few days. Federspiel's small world .gif file view of the path is available here but more detail can be found by using my Feb. 4th prediction map of the USA also there (it used observations up to Jan. 29) and realizing that the new path is 0.4 path-width south of the one shown there (and the times 0.4 minutes earlier).
A recent satellite image shows it mostly clear across Fla. and GA, with a large clear spot also in central Okla. and the northernmost part of Texas, to Dallas and areas west of there. It shows thick cloudcover from eastern Okla. to western Mississippi, with partly to mostly cloudy skies over Alabama and the areas west of central Olka. Federspiel's prediction data are below. Good luck with your observations!
David Dunham, IOTA, 1998 Feb. 17
David, This is my update for the Arethusa event tomorrow morning. As for the Catriona event I used exclusively Ron Stone's 15 highly accurate USNO positions to calculate an orbit of Arethusa which should be valid and accurate enough to predict a good position at the present time, i.e. Feb 18. The rms residuals (0.10" in RA, 0.07" in DE) are not quite as good as they were for Catriona. With Ron's position of the star I get the following path, which is shifted roughly 5 path widths southward compared to the path plotted in Sky & Telescope and now crosses the US from northern Florida to a point south of Seattle: Central line for an occultation by (95) Arethusa (95) Arethusa occults TAC -5 6044 (RA 9 33 11.3674 DE -5 11 19.190) orbit from USNO positions (Nov 24-Feb 14) only, star USNO Minimum geocentric distance:=20 date: 1998 2 18 time: 6 13 51.UT; d=3D2.44", PW=3D19.88 deg, pi=3D3.97", mu=3D30.90"/h substellar point on earth (lat., E. long.), PA of least distance: -5.18 -98.20 19.88 East Lat. Long. hh:mm:ss UT StarAlt StarAzi SunAlt SunAzi 17.91 -10.33 6: 7:48. ! 2.2 263.9 -14.7 97.8 17.52 -22.39 6: 8: 3. ! 13.3 260.1 -26.0 94.7 17.71 -28.21 6: 8:18. ! 18.6 258.0 -31.5 93.1 18.03 -32.75 6: 8:34. ! 22.7 256.2 -35.8 91.6 18.41 -36.63 6: 8:49. ! 26.1 254.4 -39.4 90.2 18.85 -40.09 6: 9: 5. ! 29.1 252.6 -42.6 88.7 19.31 -43.27 6: 9:20. ! 31.7 250.8 -45.6 87.1 19.80 -46.23 6: 9:35. ! 34.1 248.9 -48.2 85.4 20.32 -49.02 6: 9:51. ! 36.3 247.0 -50.7 83.6 20.86 -51.67 6:10: 6. ! 38.3 244.9 -53.1 81.6 21.41 -54.22 6:10:22. ! 40.1 242.8 -55.3 79.4 21.99 -56.68 6:10:37. ! 41.8 240.6 -57.3 77.0 22.57 -59.06 6:10:52. ! 43.3 238.2 -59.3 74.3 23.17 -61.38 6:11: 8. ! 44.8 235.8 -61.1 71.4 23.79 -63.65 6:11:23. ! 46.0 233.2 -62.8 68.1 24.42 -65.88 6:11:39. ! 47.2 230.5 -64.3 64.5 25.06 -68.07 6:11:54. ! 48.2 227.7 -65.7 60.4 25.72 -70.23 6:12: 9. ! 49.2 224.8 -67.0 56.0 26.38 -72.36 6:12:25. ! 49.9 221.7 -68.1 51.1 27.07 -74.48 6:12:40. ! 50.6 218.6 -69.0 45.8 27.76 -76.59 6:12:56. ! 51.1 215.3 -69.7 40.1 28.47 -78.68 6:13:11. ! 51.6 212.0 -70.3 34.0 29.19 -80.78 6:13:26. ! 51.8 208.7 -70.6 27.7 29.92 -82.87 6:13:42. ! 52.0 205.2 -70.6 21.3 30.67 -84.97 6:13:57. ! 52.0 201.7 -70.5 14.8 31.43 -87.08 6:14:13. ! 51.9 198.3 -70.1 8.6 32.21 -89.21 6:14:28. ! 51.6 194.8 -69.5 2.6 33.00 -91.35 6:14:44. ! 51.2 191.3 -68.7 356.9 33.81 -93.53 6:14:59. ! 50.7 187.8 -67.7 351.5 34.63 -95.73 6:15:14. ! 50.1 184.4 -66.5 346.6 35.48 -97.97 6:15:30. ! 49.3 181.0 -65.2 342.0 36.34 -100.26 6:15:45. ! 48.5 177.6 -63.8 337.8 37.22 -102.60 6:16: 1. ! 47.5 174.3 -62.2 333.9 38.13 -105.01 6:16:16. ! 46.3 171.0 -60.6 330.2 39.06 -107.48 6:16:31. ! 45.1 167.8 -58.8 326.8 40.01 -110.05 6:16:47. ! 43.7 164.6 -56.9 323.5 40.99 -112.72 6:17: 2. ! 42.2 161.4 -54.9 320.4 42.01 -115.51 6:17:18. ! 40.5 158.2 -52.8 317.4 43.06 -118.45 6:17:33. ! 38.7 155.0 -50.6 314.5 44.14 -121.56 6:17:48. ! 36.7 151.8 -48.2 311.5 45.27 -124.89 6:18: 4. ! 34.6 148.4 -45.7 308.6 46.45 -128.49 6:18:19. ! 32.3 145.0 -43.1 305.5 47.70 -132.44 6:18:35. ! 29.7 141.3 -40.2 302.3 49.01 -136.87 6:18:50. ! 26.8 137.3 -37.0 298.7 50.43 -141.95 6:19: 5. ! 23.5 132.9 -33.5 294.8 51.99 -148.07 6:19:21. ! 19.6 127.7 -29.4 290.0 53.77 -156.09 6:19:36. ! 14.7 120.9 -24.3 283.8 56.15 -169.84 6:19:52. ! 6.6 109.5 -16.1 273.0 I consider the possible error of this path to be about 0.15" or 1.6 path widths. Martin
