3/19/99 Asterope Update


Subject: Sun. night Asterope occ'n, Hawaii, Calif. to NYC

 Here is Jan Manek's update for the occultation of a 10.4-mag. star
 in Canis Minor by the 108km asteroid 233 Asterope.  The path has
 shifted 3.5 +/-2 path-widths north of the basic IOTA/Goffin prediction,
 with the time 3 minutes early.  This means that the occultation
 could occur in Hawaii around 5:38 UT March 22nd UT, central Calif.
 at 5:50 UT, Las Vegas at 5:51, central Colorado at 5:53, just north
 of (maybe over) Kansas City at 5:54; central Illinois & northern
 Indiana at 5:55 U.T.; and northern Ohio, most of Pennsylvania, northern
 New Jersey, New York City, and Long Island at 5:56 U.T. (56 minutes
 after midnight EST).  But with the current uncertainties in the path,
 the event could occur as far north as San Francisco, Ft. Collins,
 Des Moines, Chicago, Detroit, Buffalo, Albany, and Boston, or as
 far south as Los Angeles, Flagstaff, Puebla, Wichita, St. Louis,
 Cincinnati, DC, Fredericksburg (VA), and Delaware.  The prediction
 might be refined during the next couple of days, especially if CCD
 observations of both the star and the relatively slowly-moving
 asteroid on the same frame can be obtained and reduced with USNO
 A2.0 or ACT data.  IOTA's finder chart for locating the star, and
 maps showing the updated path, can be found at
 "http://members.home.net/dega/astchart.htm"Asteroidal Chart Web
 Page
 Future updates will also be available there, and at IOTA's main
 site at http://www.lunar-occultations.com/iota/ once it is restored
 (that should occur sometime today), and on the IOTA phone line
 at 301-474-4945.  Besides encouraging observers at fixed sites to
 try to time the occultation, those with a mobile capability are
 encouraged to try to observe from locations in the path to fill
 gaps in local coverage of the fixed sites.  We plan an expedition from
 the DC area to attempt observations across Pennsylvania, but the
 long-range weather forecast is unfavorable for this area.

 David Dunham, IOTA, 1999 March 19, 6h U.T.
 ______________________________________________________________________

 Date: Thu, 18 Mar 1999 19:08:06 +0100
 To: Joan and David Dunham <dunham@erols.com
 From: Jan Manek <jmanek@mbox.vol.cz
 Subject: Update for (233) Asterope on March 21/22, 1999

                        IOTA/IOTA-ES occultation update for
           (233) Asterope  / TYC 0773 01067 1 event on 1999, March 21/22
                 visible from Hawai and most US from west to east


 Summary

 On the night March 21/22, 1999 will be occulted 10.4 mag star by a 108km
 asteroid (233) Asterope. This update is based on USNO/Flagstaff and TMO
 astrometry for asteroid and ACT star position. The asteroid is moving
quite
 slowly; only 12"/hour; so the duration will be rather long ~19 seconds.
The
 magnitude drop is large so the event should be well observable. The main
 source
 of uncertainity is the star's position.

 The event at one glimpse:
  * date and approx. UT time of event: March, 3, 1999 @ 05:38 UT (Hawai)
                                     05:50 UT (W USA) - 05:57 UT (E USA)
  * magnitude of target star: 10.4
  * magnitude drop [mag]: 3.0
  * estimated maximum duration [s]: 19.2
  * path description:  See above.  Observers up to 200km of
      this path are within expected path errors. For details consult
      the maps on the Web site given above.

 The occultation path:
  * approximate width [km]: 110
  * uncertainty [path widths]: 2
  * uncertainty in time [s]: 40
  * remarks: Path uncertainities are given according to nominal star
position
     errors and expected asteroid positional accuracy.
 CONCERNING the maps showing the updated path on the Web:
     Please follow the circles rather than the plotted path.
     !!!!!!!
     Circles along the path are OCCULT exactly calculated centerline
points.
     !!!!!!!
 Remember the +/-2 path-widths uncertainty.

 Data for the target star:
  * name: TYC 0773 01067 1
  * constellation: Canis Minor
  * J2000 position [h,m,s; o,',"]: 07h 36m 09.498s; +12o 03' 30.28"
  * position source: ACT
  * estimated accuracy ["]: 0.08"  (0.06", 0.04")
  * V mag [mag]: 10.40
  * B-V [mag]: +1.41
  * remarks:
      TYCHO quality flag is 7 indicating LOW quality position together with
      X flag indicating it is not suitable as astrometric reference.
      TRC gives position close to ACT, but this problem remains.
      True star position error may be much larger than nominal.

 Data for the minor planet:
  * general information:
      number, name: (233) Asterope
      approx. diameter [km]: 108
  * orbital information
      orbit source: calculation Manek
      source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill
Owen)
      number of used observations: 38 USNO, 7 TMO
      number of rejected observations: 1 USNO (1998 12 28.390828)
      time covered by the observations: 1998 11 04 - 1999 03 13
      rms residuals ["] (RA,DE): 0.09", 0.07"
      estimated positional accuracy at epoch of event ["]: 0.08"
      remarks: Rejection of the one USNO position was not significant.

 Data for the event:
  * UT date and time of least geocentric approach: 05:38:54 UT
  * approx. V mag of minor planet at event [mag]: 13.3
  * geocentric parallax of minor planet ["]: 3.755
  * magnitude drop [mag]: 3.0
  * estimated maximum duration [s]: 19.2
  * apparent motion of minor planet ["/h]: 11.94
  * angular distance to moon, phase of moon [deg,%]: 53, 25%
  * remarks:

 Centerline path coordinates:
                                        Altitude
   E. Longitude    Latitude     U.T.    star  sun
    -162 00 00   + 13 39 39    5 35 43   77   -10
    -160 00 00   + 15 02 52    5 36 32   79   -12
    -158 00 00   + 16 24 49    5 37 22   81   -14
    -156 00 00   + 17 45 18    5 38 11   82   -16
    -154 00 00   + 19 04 06    5 39 00   82   -18
    -152 00 00   + 20 21 04    5 39 48   81   -20
    -150 00 00   + 21 36 01    5 40 35   80   -21
    -148 00 00   + 22 48 49    5 41 22   79   -23
    -146 00 00   + 23 59 22    5 42 07   77   -25
    -144 00 00   + 25 07 34    5 42 52   75   -27
    -142 00 00   + 26 13 20    5 43 35   73   -28
    -140 00 00   + 27 16 38    5 44 17   71   -30
    -138 00 00   + 28 17 24    5 44 58   69   -31
    -136 00 00   + 29 15 37    5 45 37   67   -33
    -134 00 00   + 30 11 17    5 46 16   65   -34
    -132 00 00   + 31 04 24    5 46 53   64   -35
    -130 00 00   + 31 54 58    5 47 28   62   -37
    -128 00 00   + 32 43 00    5 48 03   60   -38
    -126 00 00   + 33 28 31    5 48 36   58   -39
    -124 00 00   + 34 11 35    5 49 08   56   -40
    -122 00 00   + 34 52 12    5 49 39   54   -41
    -120 00 00   + 35 30 24    5 50 08   52   -42
    -118 00 00   + 36 06 16    5 50 37   50   -43
    -116 00 00   + 36 39 48    5 51 04   49   -44
    -114 00 00   + 37 11 03    5 51 30   47   -44
    -112 00 00   + 37 40 04    5 51 55   45   -45
    -110 00 00   + 38 06 54    5 52 19   44   -46
    -108 00 00   + 38 31 34    5 52 42   42   -46
    -106 00 00   + 38 54 07    5 53 04   40   -47
    -104 00 00   + 39 14 36    5 53 25   39   -47
    -102 00 00   + 39 33 01    5 53 45   37   -48
    -100 00 00   + 39 49 26    5 54 04   35   -48
    - 98 00 00   + 40 03 52    5 54 22   34   -48
    - 96 00 00   + 40 16 21    5 54 40   32   -49
    - 94 00 00   + 40 26 54    5 54 56   30   -49
    - 92 00 00   + 40 35 33    5 55 12   29   -49
    - 90 00 00   + 40 42 19    5 55 27   27   -49
    - 88 00 00   + 40 47 13    5 55 41   26   -49
    - 86 00 00   + 40 50 16    5 55 54   24   -49
    - 84 00 00   + 40 51 28    5 56 06   23   -49
    - 82 00 00   + 40 50 51    5 56 18   21   -48
    - 80 00 00   + 40 48 25    5 56 28   20   -48
    - 78 00 00   + 40 44 10    5 56 38   18   -48
    - 76 00 00   + 40 38 06    5 56 48   16   -48
    - 74 00 00   + 40 30 14    5 56 56   15   -47
    - 72 00 00   + 40 20 33    5 57 04   13   -47
    - 70 00 00   + 40 09 03    5 57 10   12   -46
    - 68 00 00   + 39 55 45    5 57 17   10   -46
    - 66 00 00   + 39 40 37    5 57 22    9   -45
    - 64 00 00   + 39 23 40    5 57 26    7   -45

 Calculator: Manek