Update for (124) Alkeste - April 14/15, 2003

Jan Manek's update

                    IOTA/IOTA-ES occultation update for
           (124) Alkeste / CMC 605070 on April 14/15, 2003
          visible from Libya, Tunisia, NE Algeria and Spain

Summary 

In the night of April 14/15, 2003 a faint 11.8 mag star CMC 605070 will be occulted by a 80 km asteroid (124) Alkeste. This update is based on USNO/Flagstaff and TMO astrometry for the asteroid and recent UCAC star position.

The updated path shows no path shift with time 0.4 minutes earlier compared to Edwin Goffin's nominal prediction.

Updated path runs over Libya around 23:35 UT, south Tunisia ~23:37.0 UT, NE Algeria ~23:38.1 UT and finally Spain around 23:40.5 UT with Madrid on south limit. Please check the path chart for details.

There are two circumstances making this event a harder one. First is almost full Moon, only 9-10 degrees east of target star. Second is slightly uncertain CMC V-band magnitude used for brightness drop, which is therefore also slightly uncertain. I would expect the star's visual magnitude to be brighter by 0.1-0.2 magnitudes compared to V-band photometry so the drop could be slightly larger than expected 0.8 magnitudes. Video recording is highly welcomed. Clear sky and good luck !!!

The event at one glimpse:
 * date and approx. UT time of event: April 14, 2003 @ 23:40 UT (Europe)
 * magnitude of target star: 11.8
 * magnitude drop [mag]: 0.8
 * estimated maximum duration [s]: 11.7
 * path description: given above
 * Goffin's original chart reference: A03_0420

The occultation path:
 * approximate ground width [km]: 110
 * uncertainty [path widths]: 1.6
 * uncertainty in time [s]: 7
 * map: below
 * remarks: Path uncertainties are given according to nominal star
    position errors and expected asteroid positional accuracy.

Data for the target star:
 * name: CMC 605070 = GSC 0267-00564
 * constellation: Leo
 * J2000 position [h,m,s; o,',"]: 11h 25m 12.7541s; +03o 20' 08.769"
 * position source: recent UCAC position combined with derived proper motion
 * estimated accuracy ["]: 0.03" (0.02", 0.02")
 * V mag [mag]: 11.78 according to CMC
 * B-V [mag]: +0.9   estimate from AC 2000.2 BT mag
 * remarks:
    Recent UCAC position was provided by Marion and Norbert Zacharias.
    Proper motion was derived newly from AC2000.2, CMC9 and recent UCAC star position.
    Target star is in southeast Leo, about 50' NW of 4.9 mag star tau Leonis = SAO 118875
    or 7' west of 6.7 mag star SAO 118847.
    !!! 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 12.5
 * labeled stars have indicated SAO numbers
 * remarks: Second chart is 30' blowup to show correctly the target star in the field.











Data for the minor planet:
 * general information:
     number, name: (124) Alkeste
     approx. diameter [km]: 80
 * orbital information
     orbit source: calculation Manek
     source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
     number of used observations: 119 USNO, 12 TMO
     number of rejected observations: 7 USNO, 2 TMO
     time covered by the observations: 1998 02 12 - 2003 03 31
     rms residuals ["] (RA,DE): 0.07", 0.07"
     estimated positional accuracy at epoch of event ["]: 0.03", 0.04"
     remarks: No recent opposition astrometry.

Data for the event:
 * UT date and time of least geocentric approach: 23:39.3 UT
 * approx. V mag of minor planet at event [mag]: 11.9
 * geocentric parallax of minor planet ["]: 5.343
 * magnitude drop [mag]: 0.8
 * estimated maximum duration [s]: 11.7
 * apparent motion of minor planet ["/h]: 20.53
 * angular distance to moon, phase of moon [deg,%]: 10, 95%
 * remarks:

Elements for WinOccult:
============ cut here ===========================================
 2003 Apr 14
124 Alkeste
23h 39.3m UT
CMC 605070  11.8   11 25 12.754  3 20  8.77
11.9     80   11.7   1.646    -1.161     10.87
  -26.258   3.334  -174.76    9.54
 23.6554   .35784   .57379 -3.25878  2.03709  0.00289 -0.00120
2000    299.4406922003 411.0000062.717570 188.1959822.950207  0.076034412.630224852.430237268.105   0.19
RATE 2.3105470 .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  '  "
     23  0  0    24 30 30   23 33 30    39   253   -53   25  4 36   23 56 45   25 44 38   23 18  2
     22  0  0    25  3 23   23 33 45    40   252   -52   25 37 41   24 29 27   26 17 57   23 50 32
     21  0  0    25 36 47   23 33 59    41   251   -52   26 11 16   25  2 39   26 51 46   24 23 31
     20  0  0    26 10 39   23 34 14    41   250   -52   26 45 21   25 36 20   27 26  5   24 56 59
     19  0  0    26 45  1   23 34 29    42   249   -52   27 19 54   26 10 30   28  0 53   25 30 55
     18  0  0    27 19 50   23 34 44    42   248   -52   27 54 56   26 45  7   28 36 10   26  5 19
     17  0  0    27 55  6   23 34 59    43   246   -51   28 30 25   27 20 11   29 11 54   26 40 10
     16  0  0    28 30 49   23 35 15    43   245   -51   29  6 20   27 55 42   29 48  4   27 15 27
     15  0  0    29  6 56   23 35 31    44   244   -51   29 42 40   28 31 37   30 24 40   27 51  8
     14  0  0    29 43 28   23 35 46    44   242   -50   30 19 25   29  7 56   31  1 41   28 27 14
     13  0  0    30 20 24   23 36  2    45   241   -50   30 56 34   29 44 39   31 39  5   29  3 43
     12  0  0    30 57 41   23 36 18    45   240   -49   31 34  5   30 21 44   32 16 52   29 40 33
     11  0  0    31 35 20   23 36 34    46   238   -49   32 11 57   30 59 11   32 55  1   30 17 45
     10  0  0    32 13 20   23 36 50    46   237   -48   32 50 10   31 36 57   33 33 30   30 55 17
      9  0  0    32 51 38   23 37  7    46   235   -48   33 28 42   32 15  2   34 12 18   31 33  8
      8  0  0    33 30 14   23 37 23    46   234   -47   34  7 31   32 53 25   34 51 24   32 11 17
      7  0  0    34  9  7   23 37 39    47   232   -46   34 46 38   33 32  5   35 30 47   32 49 43
      6  0  0    34 48 16   23 37 55    47   231   -46   35 26  0   34 11  1   36 10 25   33 28 24
      5  0  0    35 27 38   23 38 12    47   229   -45   36  5 36   34 50 10   36 50 18   34  7 19
      4  0  0    36  7 14   23 38 28    47   227   -44   36 45 25   35 29 33   37 30 24   34 46 27
      3  0  0    36 47  1   23 38 44    47   226   -44   37 25 25   36  9  7   38 10 40   35 25 47
      2  0  0    37 26 58   23 39  1    47   224   -43   38  5 36   36 48 51   38 51  7   36  5 17
      1  0  0    38  7  4   23 39 17    47   222   -42   38 45 55   37 28 44   39 31 43   36 44 56
      0  0  0    38 47 17   23 39 33    47   221   -42   39 26 22   38  8 45   40 12 25   37 24 42
   -  1  0  0    39 27 36   23 39 49    47   219   -41   40  6 54   38 48 51   40 53 13   38  4 35
   -  2  0  0    40  7 59   23 40  5    47   217   -40   40 47 30   39 29  2   41 34  5   38 44 32
   -  3  0  0    40 48 25   23 40 21    47   216   -39   41 28  9   40  9 16   42 14 59   39 24 33
   -  4  0  0    41 28 52   23 40 37    47   214   -38   42  8 48   40 49 32   42 55 54   40  4 35
   -  5  0  0    42  9 19   23 40 53    47   213   -38   42 49 27   41 29 47   43 36 48   40 44 38
   -  6  0  0    42 49 44   23 41  8    46   211   -37   43 30  4   42 10  1   44 17 40   41 24 39
   -  7  0  0    43 30  6   23 41 24    46   209   -36   44 10 37   42 50 11   44 58 27   42  4 38
   -  8  0  0    44 10 22   23 41 39    46   208   -35   44 51  4   43 30 17   45 39  8   42 44 32
   -  9  0  0    44 50 32   23 41 54    46   206   -34   45 31 25   44 10 16   46 19 41   43 24 20
   - 10  0  0    45 30 33   23 42  9    45   205   -34   46 11 36   44 50  8   47  0  5   44  4  0
   - 11  0  0    46 10 24   23 42 24    45   203   -33   46 51 37   45 29 50   47 40 18   44 43 32
   - 12  0  0    46 50  3   23 42 38    45   201   -32   47 31 26   46  9 20   48 20 18   45 22 53
   - 13  0  0    47 29 30   23 42 53    44   200   -31   48 11  1   46 48 38   49  0  4   46  2  2
   - 14  0  0    48  8 41   23 43  7    44   198   -30   48 50 21   47 27 42   49 39 34   46 40 57
   ........................................ 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-|
--------------------------------------------------------------------U---U---