'Update' for (468) Lina - July 21, 1999

Martin Federspiel's update

                     IOTA/IOTA-ES occultation update for 
                 (468) Lina/HIP 5995 event on 1999 July 21
                visible from Libya, Greece, Turkey, Black Sea


Summary 

Around 1h 45m UT of 1999 July 21 the 70 km large asteroid (468) Lina will occult a 9.3 mag star in Pisces for observers in Libya, Greece, eastern Turkey, and the Black Sea.

This is not a usual update. Unfortunately, the orbit "improvement" had to be calculated from USNO observations covering only 5 months in 1998 (!). No positions from other sources (CAMC, Bordeaux, Table Mountain etc.) were available to me. The resulting path is about 200 km southeast and 18 minutes earlier than Edwin Goffin's nominal prediction. The nominal prediction is well confirmed with Bowell's orbit from the Lowell data base.

Given the uncertainty of the Federspiel/USNO solution the nominal prediction is the best that can be said from the available data. However, the nominal prediction is pretty uncertain, too.

The event at one glimpse:
 * date and approx. UT time of event: 1999 July 21, 1h 45m UT
 * magnitude of target star: 9.3
 * magnitude drop [mag]: 5.2
 * estimated maximum duration [s]: 5
 * rough path description (may be significantly in error): Eastern Libya, 
   southern Greece, northwestern Turkey, Istanbul, Black Sea

The occultation path:
 * approximate widths [km]: 70
 * more detailed path description: does not make sense
 * uncertainty [path widths]: 10
 * map: attached
 * remarks: path of Goffin's nominal prediction is most likely one,
   but is considerably uncertain

Data for the target star:
 * name: HIP 5995
 * constellation: Pisces
 * J2000 position [h,m,s; °,',"]: RA 1 17 5.142 DE +7 54 49.69 
 * position source: Hipparcos
 * estimated accuracy ["]: 0.01
 * V mag [mag]: 9.34
 * remarks:

Data for the minor planet:
 * general information:
     mumber, name: (468) Lina
     approx. diameter [km]: 70
 * orbital information
     orbit source: 2 solutions: 1.) Bowell orbit 2.) Federspiel from USNO positions
     source of used astrometry: USNO (for Federspiel orbit)
     number of used observations: 29
     number of rejected observations: 10
     time covered by the observations: *1998* Apr - *1998* Aug
     rms residuals ["] (RA,DE): 0.09,0.09
     estimated positional accuracy at epoch of event ["]: 0.5
     remarks: Federspiel orbit not very accurate, because observations
     cover a rather short arc and are too far from the epoch of the
     event

Data for the event:
 * UT date and time of least geocentric approach: 1999 7 21 @ 1 45 58.UT
   (orbit Bowell); 1999 7 21 @ 1 28 13.UT (inaccurate orbit Federspiel)
 * least geocentric distance ["]: 2.55 (both solutions)
 * uncertainty in time [s]: 530
 * approx. V mag of minor planet at event [mag]: 14.6
 * geocentric parallax of minor planet ["]: 4.03
 * magnitude drop [mag]: 5.3
 * estimated maximum duration [s]: 5
 * apparent motion of minor planet ["/h]: 34.20
 * angular distance to moon, phase of moon [°,%]: 164°, 57+
 * remarks:

Calculator(s): Martin Federspiel





Path coordinates:

     more probable solution with orbit Bowell:

     Lat.     Long. hh:mm:ss UT  StarAlt° StarAzi°  SunAlt°  SunAzi°
     17.44   -33.22  1:40:31. !      3.6     82.8    -50.8    345.6
     19.64   -22.85  1:40:45. !     13.5     86.3    -49.8      1.1
     21.14   -17.43  1:40:59. !     18.6     88.5    -47.8      8.7
     22.46   -13.20  1:41:13. !     22.6     90.6    -45.8     14.2
     23.70    -9.59  1:41:27. !     26.0     92.7    -43.6     18.5
     24.88    -6.38  1:41:42. !     28.9     94.7    -41.5     22.0
     26.01    -3.43  1:41:56. !     31.4     96.8    -39.4     25.0
     27.12     -.69  1:42:10. !     33.8     99.0    -37.3     27.7
     28.20     1.91  1:42:24. !     35.9    101.2    -35.2     30.0
     29.26     4.38  1:42:38. !     37.8    103.6    -33.1     32.2
     30.31     6.76  1:42:52. !     39.6    106.0    -31.1     34.1
     31.34     9.06  1:43: 6. !     41.2    108.6    -29.1     35.9
     32.37    11.30  1:43:20. !     42.7    111.3    -27.1     37.7
     33.38    13.50  1:43:35. !     44.1    114.1    -25.1     39.3
     34.39    15.65  1:43:49. !     45.3    117.0    -23.2     40.9
     35.40    17.78  1:44: 3. !     46.4    120.1    -21.2     42.4
     36.40    19.89  1:44:17. !     47.4    123.2    -19.3     43.9
     37.39    21.99  1:44:31. !     48.2    126.5    -17.4     45.4
     38.39    24.09  1:44:45. !     48.9    129.9    -15.4     46.8
     39.38    26.18  1:44:59. !     49.5    133.4    -13.5     48.3
     40.37    28.29  1:45:14. !     50.0    137.0    -11.6     49.8
     41.36    30.41  1:45:28. !     50.3    140.7     -9.7     51.2
     42.34    32.55  1:45:42. !     50.5    144.5     -7.8     52.7
     43.33    34.72  1:45:56. !     50.6    148.3     -5.9     54.3
     44.32    36.93  1:46:10. !     50.6    152.2     -4.0     55.9

probably less accurate solution Federspiel:

     Lat.     Long. hh:mm:ss UT  StarAlt° StarAzi°  SunAlt°  SunAzi°
     17.47   -28.16  1:22:47. !      4.1     82.9    -50.9    346.5
     19.60   -18.23  1:23: 1. !     13.6     86.3    -49.8      1.3
     21.10   -12.85  1:23:15. !     18.8     88.6    -47.9      8.9
     22.42    -8.64  1:23:29. !     22.7     90.6    -45.8     14.3
     23.65    -5.04  1:23:43. !     26.1     92.7    -43.6     18.6
     24.83    -1.83  1:23:57. !     28.9     94.7    -41.5     22.1
     25.96     1.10  1:24:11. !     31.5     96.8    -39.4     25.2
     27.07     3.85  1:24:25. !     33.9     99.0    -37.3     27.8
     28.15     6.43  1:24:40. !     36.0    101.3    -35.2     30.1
     29.21     8.90  1:24:54. !     37.9    103.6    -33.1     32.3
     30.26    11.28  1:25: 8. !     39.7    106.1    -31.1     34.2
     31.29    13.58  1:25:22. !     41.3    108.6    -29.1     36.0
     32.31    15.82  1:25:36. !     42.8    111.3    -27.1     37.8
     33.33    18.01  1:25:50. !     44.1    114.1    -25.1     39.4
     34.34    20.17  1:26: 4. !     45.4    117.0    -23.1     41.0
     35.34    22.30  1:26:19. !     46.5    120.1    -21.2     42.5
     36.34    24.41  1:26:33. !     47.4    123.2    -19.3     44.0
     37.33    26.51  1:26:47. !     48.3    126.5    -17.3     45.5
     38.33    28.60  1:27: 1. !     49.0    129.9    -15.4     46.9
     39.32    30.70  1:27:15. !     49.6    133.4    -13.5     48.4
     40.31    32.80  1:27:29. !     50.1    137.0    -11.6     49.8
     41.29    34.92  1:27:43. !     50.4    140.7     -9.7     51.3
     42.28    37.06  1:27:57. !     50.6    144.5     -7.8     52.8
     43.27    39.23  1:28:12. !     50.7    148.4     -5.9     54.3
     44.26    41.43  1:28:26. !     50.7    152.2     -4.0     55.9

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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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