Update for (405) Thia - July 10/11, 2003

Jan Manek's update

                    IOTA/IOTA-ES occultation update for
             (405) Thia / TAC -00 08821 on July 10/11, 2003
              visible N Egypt, N Libya, Tunisia, N Algeria,
            N Morocco, very S Spain and Portugalfrom any land

Summary 

In the night of July 10/11, 2003 a faint 11.2 mag star TAC -00 08821 will be occulted by a 129 km asteroid (405) Thia. This update is based on USNO/Flagstaff and TMO astrometry for the asteroid and UCAC2-beta star position.

The updated path shows no path shift with time ~0.3 minutes later compared to Edwin Goffin's nominal prediction.

Updated path runs over N Egypt ~01:01 UT, N Libya 01:02.0-01:04.0 UT, Tunisia ~01:04.5 UT, N Algeria ~01:06 UT, N Morocco ~01:06.5 UT, very S Spain ~01:06.7 UT and very S Portugal ~01:07.1 UT. Please check the path chart for details.

Clear sky and good luck !!!

The event at one glimpse:
 * date and approx. UT time of event: July 11, 2003 @ 01:07 UT
 * magnitude of target star: 11.2
 * magnitude drop [mag]: 1.5
 * estimated maximum duration [s]: 13.3
 * path description: given above
 * Goffin's original chart reference: A03_0735

The occultation path:
 * approximate ground width [km]: 155
 * uncertainty [path widths]: 0.8
 * uncertainty in time [s]: 11
 * map: below
 * remarks: Path uncertainties are given according to nominal star
    position errors and expected asteroid positional accuracy.

Data for the target star:
 * name: TAC -00 08821
 * constellation: Aquarius
 * J2000 position [h,m,s; o,',"]: 21h 10m 39.3993s; -00o 50' 15.334"
 * position source: recent UCAC2 beta
 * estimated accuracy ["]: 0.04" (0.03", 0.02")
 * V mag [mag]: 11.15
 * B-V [mag]: +0.90
 * remarks:
    Target star is in northwest Aquarius, about 7.1 degrees NW of 2.9 mag star beta Aquarii = SAO 145457.
    Target is main (brighter) component in a pair, fainter is ~9" to SW and ~2.5 magnitudes fainter.
    It is not excluded (although no indications are present in UCAC2) that the secondary star influenced
    on the main component position. In such case the path would shift slightly to north.
    !!! IMPORTANT !!!
    Purple stars in identification chart are so called 'non-star' objects in GSC; in dense fields
    the 'non-stars' are often real stars or blends of close pairs. Be careful about this.

Close finding chart (prepared in GUIDE8):
 * occulted star is in center - labeled with cross
 * field is 3.0x3.0 degrees
 * limiting magnitude is 13.0
 * labeled stars have indicated SAO numbers
 * remarks: Second chart shows 30' blowup to show correctly the star in field.











Data for the minor planet:
 * general information:
     number, name: (405) Thia
     approx. diameter [km]: 129
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
     number of used observations: 125 USNO, 2 TMO
     number of rejected observations: 9 USNO
     time covered by the observations: 1998 02 05 - 2003 06 27
     rms residuals ["] (RA,DE): 0.08", 0.08"
     estimated positional accuracy at epoch of event ["]: 0.08", 0.08"
     remarks:

Data for the event:
 * UT date and time of least geocentric approach: 01:02.6 UT
 * approx. V mag of minor planet at event [mag]: 12.4
 * geocentric parallax of minor planet ["]: 5.238
 * magnitude drop [mag]: 1.5
 * estimated maximum duration [s]: 13.3
 * apparent motion of minor planet ["/h]: 28.60
 * angular distance to moon, phase of moon [deg,%]: 70, 90%
 * remarks:

Elements for WinOccult:
============ cut here ===========================================
 2003 Jul 11
405 Thia
 1h  2.6m UT
 -00 08821  11.2   21 10 39.399- 0 50 15.33TAC -00 08821
12.4    129   13.3   1.679    -1.865      5.98
   13.485  -0.839  -194.29   22.18
  1.0427   .11064   .51722 -5.33956  1.14328 -0.00233 -0.00199
2000    75.56313882003 710.00000309.134012255.32760411.947476 0.244170222.584422241.953383298.465   0.15
RATE 2.3722414 .0000000 .0000000 .0000000 .00000000 .00000000 .00000000
============ cut here ===========================================

Calculator(s): Jan Manek








Path coordinates:
                  Centre              Star  Star   Sun      Path Limits           Error Limits
  E. Longitude   Latitude      U.T.    Alt    Az   Alt    Limit 1    Limit 2    Limit 3    Limit 4
                                                         Latitude   Latitude   Latitude   Latitude
    ...................................... shortened .............................................
      o  '  "     o  '  "    h  m  s     o     o     o    o  '  "    o  '  "    o  '  "    o  '  "
     48  0  0    25 12 56    0 58 13    49   236   -14   25 55  1   24 31 10   27  2 12   23 25 49
     46  0  0    25 34 19    0 58 31    50   234   -15   26 16 26   24 52 30   27 23 42   23 47  5
     44  0  0    25 56  9    0 58 49    51   232   -17   26 38 19   25 14 18   27 45 38   24  8 49
     42  0  0    26 18 25    0 59  8    52   229   -18   27  0 37   25 36 32   28  8  1   24 30 59
     40  0  0    26 41  4    0 59 27    53   226   -19   27 23 20   25 59  9   28 30 47   24 53 32
     38  0  0    27  4  6    0 59 46    54   223   -20   27 46 24   26 22  9   28 53 55   25 16 28
     36  0  0    27 27 28    1  0  6    55   220   -21   28  9 48   26 45 28   29 17 23   25 39 45
     34  0  0    27 51  9    1  0 25    56   217   -22   28 33 31   27  9  7   29 41 10   26  3 20
     32  0  0    28 15  6    1  0 45    56   214   -23   28 57 30   27 33  2   30  5 13   26 27 12
     30  0  0    28 39 18    1  1  4    57   210   -24   29 21 44   27 57 12   30 29 30   26 51 19
     28  0  0    29  3 43    1  1 24    57   207   -25   29 46 11   28 21 35   30 54  0   27 15 39
     26  0  0    29 28 19    1  1 44    58   203   -26   30 10 49   28 46  9   31 18 40   27 40 10
     24  0  0    29 53  4    1  2  3    58   200   -26   30 35 35   29 10 52   31 43 29   28  4 51
     22  0  0    30 17 56    1  2 23    58   196   -27   31  0 29   29 35 43   32  8 26   28 29 39
     20  0  0    30 42 53    1  2 43    58   192   -28   31 25 28   30  0 39   32 33 27   28 54 34
     18  0  0    31  7 54    1  3  2    58   189   -28   31 50 30   30 25 39   32 58 31   29 19 31
     16  0  0    31 32 57    1  3 22    58   185   -29   32 15 34   30 50 40   33 23 36   29 44 31
     14  0  0    31 57 59    1  3 41    57   181   -29   32 40 37   31 15 42   33 48 41   30  9 32
     12  0  0    32 22 59    1  4  0    57   178   -30   33  5 38   31 40 41   34 13 43   30 34 30
     10  0  0    32 47 56    1  4 19    56   174   -30   33 30 35   32  5 37   34 38 41   30 59 25
      8  0  0    33 12 47    1  4 38    56   171   -31   33 55 26   32 30 28   35  3 33   31 24 15
      6  0  0    33 37 30    1  4 56    55   168   -31   34 20  9   32 55 11   35 28 17   31 48 58
      4  0  0    34  2  4    1  5 14    54   165   -31   34 44 43   33 19 45   35 52 51   32 13 32
      2  0  0    34 26 27    1  5 32    53   162   -31   35  9  6   33 44  8   36 17 14   32 37 56
      0  0  0    34 50 38    1  5 50    52   159   -31   35 33 17   34  8 19   36 41 23   33  2  7
   -  2  0  0    35 14 34    1  6  8    52   156   -31   35 57 13   34 32 16   37  5 18   33 26  5
   -  4  0  0    35 38 15    1  6 25    50   153   -31   36 20 53   34 55 58   37 28 57   33 49 48
   -  6  0  0    36  1 38    1  6 41    49   151   -31   36 44 15   35 19 22   37 52 18   34 13 13
   -  8  0  0    36 24 43    1  6 58    48   148   -31   37  7 18   35 42 27   38 15 19   34 36 20
   - 10  0  0    36 47 27    1  7 14    47   146   -31   37 30  1   36  5 13   38 38  0   34 59  7
   - 12  0  0    37  9 49    1  7 30    46   144   -31   37 52 22   36 27 36   39  0 18   35 21 33
   - 14  0  0    37 31 48    1  7 45    45   141   -30   38 14 19   36 49 37   39 22 13   35 43 36
   - 16  0  0    37 53 23    1  8  0    43   139   -30   38 35 52   37 11 13   39 43 43   36  5 15
    ...................................... shortened .............................................

----------------------------------------------------------------------------
Jan Manek
Stefanik Observatory                Private :
Petrin 205                          Werichova 950
118 46  Praha 1                     152 00  Praha 5 - Barrandov     |_|_|
Czech Republic                      Czech Republic                  /   \
Internet : jan.manek@worldonline.cz                                |-O-O-|
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