Hi all,
I have just finished the computation of update, based on following:
1) I have not used all 9 USNO positionsof Elpis, since the position from
June 1.4 has more than 1" error. Using remaining 8 positions the orbit was
refined and RMS is about 0.06".
2) I have used USNO position for the star.
I hope I made no error and independent check is invited.
As the path for this occultation is not in S&T Feb 98 and I don't have
anything other to compare with, I will give here a short description of the
path (see also attached 059UP.GIF).
Around 5:51 UT the shadow enters northern south Americe and goes paralel to
coast of Surinam (covers Paramaribo), enters Guayana (Gergetown is in path)
and at 5:53 runs over Venezuela, at 5:55 moves to Columbia and just misses
the capital Bogota (5:56:30 UT) while Medellin is near the southern path
limit. The path also shortly hits southernmost part of Panama and runs into
Pacific Ocean.
Path coordinates from OCCULT 4.07 are following (for the non-ocean part):
Occultation of T5725.0796 by 59 Elpis on 1998 Jun 18
E. Longitude Latitude U.T. star sun
- 94 00 00 + 8 13 56 6 00 23 50 -58
- 92 00 00 + 8 03 07 5 59 59 52 -59
- 90 00 00 + 7 52 50 5 59 33 54 -59
- 88 00 00 + 7 43 03 5 59 08 55 -59
- 86 00 00 + 7 33 48 5 58 42 57 -59
- 84 00 00 + 7 25 06 5 58 15 59 -59
- 82 00 00 + 7 16 56 5 57 48 60 -59
- 80 00 00 + 7 09 19 5 57 20 62 -58
- 78 00 00 + 7 02 16 5 56 53 64 -58
- 76 00 00 + 6 55 47 5 56 24 65 -57
- 74 00 00 + 6 49 52 5 55 56 67 -57
- 72 00 00 + 6 44 31 5 55 27 68 -56
- 70 00 00 + 6 39 45 5 54 58 69 -55
- 68 00 00 + 6 35 34 5 54 28 71 -54
- 66 00 00 + 6 31 58 5 53 59 72 -53
- 64 00 00 + 6 28 57 5 53 29 73 -52
- 62 00 00 + 6 26 31 5 52 59 74 -51
- 60 00 00 + 6 24 41 5 52 29 74 -50
- 58 00 00 + 6 23 27 5 51 59 75 -48
- 56 00 00 + 6 22 49 5 51 29 75 -47
- 54 00 00 + 6 22 46 5 50 59 75 -46
- 52 00 00 + 6 23 18 5 50 29 74 -44
- 50 00 00 + 6 24 27 5 49 59 74 -43
- 48 00 00 + 6 26 11 5 49 29 73 -42
- 46 00 00 + 6 28 31 5 49 00 72 -40
Best regards, Jan
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Jan Manek
Stefanik Observatory Private :
Petrin 205 Werichova 950
118 46 Praha 1 152 00 Praha 5 - Barrandov |_|_|
Czech Republic Czech Republic / \
Internet : jmanek@mbox.vol.cz |-O-O-|
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Dear all,
I used 8 USNO positions of (59) Elpis provided by Ron Stone to compute
an update for the occultation on June 18th. Two techniques are possible
in this case: an update based on a differential correction or an update
based on a new orbit. The latter possibility is in this case a bit risky
since there are only few positions covering a very short arc.
The residuals of the USNO positions against the MPC 24219 orbit are as
follows (the observation of June 1st omitted due to a too large residuum):
TT JD 24... cos DE(RA(o)-RA(c))° = O-C(RA)" DE(o)° - DE(c)° = O-C(DE)"Sta
50972.93055 299.467372-299.467259= .40 -9.080400- -9.080271= -.46 500
50971.93325 299.536366-299.536228= .49 -9.102970- -9.102870= -.36 500
50967.94488 299.752124-299.752012= .40 -9.213048- -9.212942= -.38 500
50960.96462 299.896614-299.896493= .43 -9.476201- -9.476109= -.33 500
50958.96891 299.883293-299.883147= .52 -9.566526- -9.566416= -.39 500
50957.97216 299.867530-299.867426= .37 -9.613941- -9.613833= -.39 500
50955.97760 299.818059-299.817972= .31 -9.713247- -9.713132= -.41 500
50953.98229 299.744824-299.744719= .37 -9.818199- -9.818078= -.43 500
mean +0.41" -0.39"
sigma 0.064" 0.038"
I don't see a very clear trend in these numbers, especially not in declination,
and take the mean values as a differential correction which I apply with
negative sign to the USNO position of the star. This procedure yields
the following central line:
Central line for an occultation by (59) Elpis
(59) Elpis occults PPM 203414 (RA 19 53 54.439 DE -8 58 16.70)
differential corrections from USNO position applied to USNO star position
Minimum geocentric distance:
date: 1998 6 18 time: 5 51 1.UT; d=1.47", PW=.14 deg, pi=4.90", mu=19.08"/h
substellar point on earth (lat., long.), PA of least distance:
-8.97 -55.57 .14
Lat. Long. hh:mm:ss UT StarAlt° StarAzi° SunAlt° SunAzi°
15.01 21.87 5:36:44. ! 13.1 256.8 20.1 70.1
14.01 15.09 5:37:15. ! 19.5 255.0 13.7 68.9
13.29 9.99 5:37:46. ! 24.4 253.6 9.0 67.9
12.71 5.69 5:38:17. ! 28.4 252.3 5.0 67.1
12.22 1.88 5:38:47. ! 32.0 251.1 1.5 66.4
11.80 -1.59 5:39:18. ! 35.2 250.0 -1.6 65.7
11.42 -4.82 5:39:49. ! 38.2 248.8 -4.6 65.0
11.09 -7.84 5:40:20. ! 40.9 247.7 -7.3 64.3
10.79 -10.72 5:40:51. ! 43.5 246.4 -9.8 63.7
10.51 -13.47 5:41:21. ! 46.0 245.2 -12.3 63.0
10.26 -16.11 5:41:52. ! 48.3 243.8 -14.6 62.4
10.04 -18.67 5:42:23. ! 50.6 242.3 -16.8 61.7
9.83 -21.15 5:42:54. ! 52.7 240.8 -18.9 61.0
9.64 -23.56 5:43:25. ! 54.7 239.1 -21.0 60.2
9.47 -25.92 5:43:56. ! 56.7 237.2 -23.0 59.5
9.32 -28.23 5:44:26. ! 58.6 235.2 -24.9 58.7
9.17 -30.50 5:44:57. ! 60.4 232.9 -26.8 57.9
9.05 -32.73 5:45:28. ! 62.1 230.4 -28.6 57.0
8.94 -34.93 5:45:59. ! 63.7 227.6 -30.3 56.1
8.83 -37.10 5:46:30. ! 65.2 224.5 -32.1 55.1
8.75 -39.25 5:47: 0. ! 66.6 221.1 -33.7 54.1
8.67 -41.38 5:47:31. ! 67.9 217.3 -35.4 53.1
8.61 -43.49 5:48: 2. ! 69.1 213.0 -37.0 51.9
8.55 -45.58 5:48:33. ! 70.2 208.3 -38.5 50.7
8.51 -47.66 5:49: 4. ! 71.0 203.1 -40.0 49.5
8.48 -49.74 5:49:34. ! 71.7 197.5 -41.5 48.1
8.46 -51.80 5:50: 5. ! 72.2 191.5 -42.9 46.6
8.45 -53.87 5:50:36. ! 72.5 185.3 -44.3 45.1
8.45 -55.93 5:51: 7. ! 72.6 178.9 -45.6 43.4
8.46 -57.99 5:51:38. ! 72.4 172.6 -46.9 41.7
8.48 -60.05 5:52: 9. ! 72.1 166.4 -48.2 39.8
8.51 -62.12 5:52:39. ! 71.5 160.6 -49.3 37.8
8.55 -64.20 5:53:10. ! 70.7 155.1 -50.5 35.6
8.60 -66.29 5:53:41. ! 69.8 150.1 -51.5 33.3
8.67 -68.39 5:54:12. ! 68.7 145.5 -52.5 30.9
8.74 -70.50 5:54:43. ! 67.5 141.4 -53.4 28.3
8.83 -72.64 5:55:13. ! 66.1 137.7 -54.2 25.5
8.93 -74.79 5:55:44. ! 64.6 134.4 -54.9 22.5
9.04 -76.97 5:56:15. ! 63.1 131.5 -55.6 19.4
9.17 -79.19 5:56:46. ! 61.4 128.8 -56.1 16.2
9.31 -81.43 5:57:17. ! 59.7 126.4 -56.5 12.7
9.46 -83.72 5:57:48. ! 57.9 124.2 -56.7 9.2
9.63 -86.05 5:58:18. ! 56.0 122.2 -56.8 5.5
9.81 -88.43 5:58:49. ! 54.0 120.4 -56.8 1.7
10.01 -90.87 5:59:20. ! 51.9 118.8 -56.6 357.8
10.23 -93.38 5:59:51. ! 49.7 117.3 -56.2 353.9
10.47 -95.96 6: 0:22. ! 47.4 115.8 -55.6 350.0
10.74 -98.65 6: 0:52. ! 45.1 114.5 -54.8 346.1
11.03 -101.44 6: 1:23. ! 42.6 113.2 -53.8 342.2
11.35 -104.38 6: 1:54. ! 39.9 112.0 -52.6 338.3
11.71 -107.47 6: 2:25. ! 37.1 110.8 -51.1 334.5
12.11 -110.79 6: 2:56. ! 34.0 109.7 -49.3 330.7
12.56 -114.38 6: 3:26. ! 30.7 108.5 -47.2 327.0
13.09 -118.36 6: 3:57. ! 26.9 107.3 -44.6 323.3
13.72 -122.92 6: 4:28. ! 22.6 106.0 -41.4 319.5
14.53 -128.50 6: 4:59. ! 17.3 104.4 -37.2 315.4
15.77 -136.74 6: 5:30. ! 9.5 102.2 -30.6 310.3
I believe this is the more trustable path.
As an alternative I also computed a new orbit based only on the eight
good USNO positions (sorry for the German); osculation epoch is
JD 2450982.700, the epoch of the occultation:
verbesserte Positionen (AE) und Geschwindigkeiten (AE/Tag):
x y z vx vy vz
.7887906 -2.4889559 -.6833916 .009601554 .004155846 .000857129
Klassische Bahnelemente nach der Variation (Oskulationsepoche JD 2450982.700):
M Perihel Knoten i e n a
(Grad) (Grad) (Grad) (Grad) (Grad/Tag) (AE)
279.23006 210.88802 170.38000 8.64576 .1185557 .22060754 2.7126212
JD Periheldurchgang: 2451348.82500 Periheldistanz q = 2.3910245
Variationskonstante: .01%
TT JD 24... cos DE(RA(o)-RA(c))° = O-C(RA)" DE(o)° - DE(c)° = O-C(DE)"Sta
50972.93055 299.467372-299.467382= -.04 -9.080400- -9.080389= -.04 500
50971.93325 299.536366-299.536350= .06 -9.102970- -9.102984= .05 500
50967.94488 299.752124-299.752135= -.04 -9.213048- -9.213044= -.02 500
50960.96462 299.896614-299.896615= .00 -9.476201- -9.476208= .03 500
50958.96891 299.883293-299.883265= .10 -9.566526- -9.566520= -.02 500
50957.97216 299.867530-299.867541= -.04 -9.613941- -9.613938= -.01 500
50955.97760 299.818059-299.818079= -.07 -9.713247- -9.713246= .00 500
50953.98229 299.744824-299.744814= .03 -9.818199- -9.818202= .01 500
rms-Werte: Rektaszension: .05 Deklination: .03
With this orbit and the USNO star position I obtain the following central
line which is 0.24" south of the above line; I repeat that I consider
this solution less accurate because the observed arc is too short for a
good orbit.
Central line for an occultation by (59) Elpis
(59) Elpis occults PPM 203414 (RA 19 53 54.467 DE - 8 58 17.09)
orbit from 8 USNO positions, star USNO
Minimum geocentric distance:
date: 1998 6 18 time: 5 51 33.UT; d=1.23", PW=.16 deg, pi=4.90", mu=19.08"/h
substellar point on earth (lat., long.), PA of least distance:
-8.97 -55.70 .16
Lat. Long. hh:mm:ss UT StarAlt° StarAzi° SunAlt° SunAzi°
13.12 28.70 5:36:45. ! 7.0 259.1 25.7 70.1
11.67 19.21 5:37:16. ! 16.2 257.0 16.7 68.8
10.83 13.34 5:37:46. ! 21.9 255.7 11.1 68.0
10.18 8.65 5:38:17. ! 26.4 254.6 6.7 67.3
9.64 4.59 5:38:48. ! 30.2 253.6 2.9 66.8
9.18 .95 5:39:19. ! 33.7 252.7 -.4 66.2
8.78 -2.40 5:39:50. ! 36.8 251.8 -3.5 65.7
8.42 -5.53 5:40:21. ! 39.7 250.9 -6.3 65.1
8.10 -8.48 5:40:51. ! 42.5 249.9 -9.0 64.6
7.81 -11.30 5:41:22. ! 45.1 248.9 -11.5 64.1
7.54 -13.99 5:41:53. ! 47.5 247.8 -13.9 63.5
7.30 -16.59 5:42:24. ! 49.9 246.7 -16.2 63.0
7.08 -19.11 5:42:55. ! 52.1 245.4 -18.4 62.4
6.88 -21.56 5:43:25. ! 54.3 244.1 -20.6 61.8
6.70 -23.94 5:43:56. ! 56.4 242.6 -22.6 61.2
6.53 -26.28 5:44:27. ! 58.4 241.0 -24.6 60.5
6.38 -28.56 5:44:58. ! 60.3 239.1 -26.6 59.8
6.24 -30.81 5:45:29. ! 62.2 237.1 -28.4 59.1
6.12 -33.02 5:45:60. ! 64.0 234.8 -30.3 58.3
6.01 -35.20 5:46:30. ! 65.7 232.2 -32.1 57.5
5.91 -37.36 5:47: 1. ! 67.3 229.2 -33.8 56.6
5.82 -39.49 5:47:32. ! 68.8 225.8 -35.5 55.7
5.75 -41.60 5:48: 3. ! 70.2 221.9 -37.2 54.7
5.68 -43.70 5:48:34. ! 71.5 217.5 -38.8 53.7
5.63 -45.78 5:49: 4. ! 72.7 212.5 -40.4 52.6
5.59 -47.85 5:49:35. ! 73.7 206.8 -41.9 51.4
5.56 -49.91 5:50: 6. ! 74.5 200.5 -43.4 50.1
5.54 -51.96 5:50:37. ! 75.1 193.6 -44.9 48.7
5.53 -54.01 5:51: 8. ! 75.4 186.2 -46.3 47.2
5.53 -56.06 5:51:39. ! 75.5 178.7 -47.7 45.6
5.54 -58.11 5:52: 9. ! 75.3 171.2 -49.1 43.9
5.56 -60.16 5:52:40. ! 74.9 164.0 -50.4 42.0
5.59 -62.22 5:53:11. ! 74.2 157.3 -51.6 40.0
5.63 -64.28 5:53:42. ! 73.3 151.2 -52.8 37.9
5.68 -66.36 5:54:13. ! 72.3 145.7 -53.9 35.6
5.75 -68.44 5:54:43. ! 71.1 140.9 -54.9 33.1
5.82 -70.55 5:55:14. ! 69.7 136.7 -55.9 30.4
5.91 -72.66 5:55:45. ! 68.3 133.0 -56.8 27.5
6.00 -74.80 5:56:16. ! 66.7 129.8 -57.6 24.5
6.11 -76.97 5:56:47. ! 65.0 127.0 -58.3 21.2
6.23 -79.16 5:57:18. ! 63.3 124.5 -58.8 17.8
6.37 -81.39 5:57:48. ! 61.5 122.3 -59.3 14.1
6.52 -83.65 5:58:19. ! 59.6 120.3 -59.6 10.3
6.68 -85.95 5:58:50. ! 57.6 118.6 -59.7 6.4
6.86 -88.31 5:59:21. ! 55.6 117.0 -59.7 2.3
7.05 -90.72 5:59:52. ! 53.5 115.5 -59.5 358.2
7.27 -93.19 6: 0:22. ! 51.3 114.2 -59.2 354.0
7.50 -95.74 6: 0:53. ! 49.0 113.0 -58.6 349.8
7.76 -98.37 6: 1:24. ! 46.6 111.9 -57.8 345.6
8.04 -101.11 6: 1:55. ! 44.1 110.9 -56.8 341.5
8.35 -103.98 6: 2:26. ! 41.5 109.9 -55.6 337.5
8.69 -106.99 6: 2:57. ! 38.6 108.9 -54.1 333.6
9.07 -110.20 6: 3:27. ! 35.6 108.0 -52.3 329.8
9.50 -113.66 6: 3:58. ! 32.4 107.1 -50.2 326.1
9.99 -117.45 6: 4:29. ! 28.8 106.1 -47.7 322.4
10.58 -121.72 6: 4:60. ! 24.7 105.1 -44.6 318.8
11.29 -126.77 6: 5:31. ! 19.9 103.9 -40.8 315.0
12.28 -133.44 6: 6: 1. ! 13.4 102.5 -35.4 310.8
For a more accurate prediction additional positions of the minor planet
close to the occultation date are necessary.
Best regards,
Martin
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Martin Federspiel ******** E-mail: martin@astro.unibas.ch
Astronomisches Institut ******** oder: federspi@astro.unibas.ch
der Universitaet Basel **** oder: federspielm@ubaclu.unibas.ch
Venusstr. 7 Telefon: (CH)-61/2055413
CH-4102 Binningen (Schweiz) Fax: (CH)-61/2055455
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