Update for (791) Ani - April 7, 2000

  • Update computed by Jan Manek;   issued 31 Mar 2000 16:34:00 +0100 (CET)

  • Jan Manek's update

                        IOTA/IOTA-ES occultation update for
              (791) Ani / TYC 1389-00373-1 event on April 7, 2000
           visible from S Ireland, S England, Belgium, S Netherlands,
       middle Germany, N Czech Republic, S Poland, NE Slovakia, S Ukraina
    
    
    Summary 

    In the night of April 7, 2000 a ~10.5 mag star TYC 1389-00373-1 = PPM 98404 will be occulted by a 107 km asteroid (791) Ani. This update is based on USNO/Flagstaff astrometry for the asteroid and Tycho-2 star position.

    The updated path shows small ~0.7 path width northern shift with time ~0.5 minutes later compared to Edwin Goffin's nominal prediction.

    The path of this occultation grazes south Ireland ~21:23 UT, runs over south England with London ~21:24.2 UT, Belgium and south Netherland ~21:25 UT, middle Germany ~21:25.5 UT with Dusseldorf, Koln and Siegen in path, north Czech Republic ~21:26 UT with Prague on south limit, southern Poland ~21:27 UT with Wroclaw just north and Krakow with Sanok in path, very NE Slovakia and finally Ukraine with Lvov and Krivoy Rog. Within expected errors is in fact a strip of Europe of ~400 km width running along latitude +50 degrees.

    Keep in mind the 3.5 path width uncertainity (this is 4 times larger uncertainity than for the successful Pales event earlier this year) and have enough time to locate the correct star. The star is faint so 20cm telescope would be needed for comfortable visual observation. There are 3 star of very similar brightness (as target star) within 6' of target forming nice triangle so they provide very nice orientation and brightness reference net.

    Please inform other observers within your area and expected path errors to have a reasonable coverage for this body. Good luck !!!

    
    The event at one glimpse:
     * date and approx. UT time of event: April 7, 2000 @ 21:26 UT
     * magnitude of target star: 10.5
     * magnitude drop [mag]: 5.1
     * estimated maximum duration [s]: 14.3
     * path description: given above
     * Goffin's original chart reference: A00_0431
    
    The occultation path:
     * approximate ground width [km]: 120
     * uncertainty [path widths]: 3.5
     * uncertainty in time [s]: 55
     * map: below
     * remarks: Path uncertainities are given according to nominal star
        position errors and expected asteroid positional accuracy.
        !!!!!!!
        Circles along path indicates the centerline for this event. 
        They are more accurate than the path limit lines.
        !!!!!!!
    
    Data for the target star:
     * name: TYC 1389-00373-1
     * constellation: Cancer
     * J2000 position [h,m,s; o,',"]: 08h 09m 20.850s; +21o 47' 06.69"
     * position source: Tycho-2  
     * estimated accuracy ["]: 0.09 (0.06", 0.07")
     * V mag [mag]: 10.52
     * B-V [mag]: +0.77
     * remarks: 
         Target star is in western Cancer, close to border with Gemini, only
         25' NE of 5.3 mag star mui2 Cancri. There are 3 star of very similar 
         brightness (as target star) within 6' of target forming nice triangle
         so they provide very nice orientation and brightness reference net.
    
    Close finding chart (prepared in GUIDE7):
     * occulted star is in center - labeled with cross
     * field is 3.0x3.0 degrees
     * limiting magnitude is 12.0
     * labeled stars have indicated SAO numbers
    
    

    Close finding chart Data for the minor planet: * general information: number, name: (791) Ani approx. diameter [km]: 107 * orbital information orbit source: calculation Manek source of used astrometry: USNO/Flagstaff (Ron Stone) number of used observations: 47 USNO number of rejected observations: 3 USNO time covered by the observations: 1998 09 14 - 2000 03 27 rms residuals ["] (RA,DE): 0.10", 0.08" estimated positional accuracy at epoch of event ["]: 0.09" remarks: Data for the event: * UT date and time of least geocentric approach: 21:17.6 UT * approx. V mag of minor planet at event [mag]: 15.6 * geocentric parallax of minor planet ["]: 2.613 * magnitude drop [mag]: 5.1 * estimated maximum duration [s]: 14.3 * apparent motion of minor planet ["/h]: 11.02 * angular distance to moon, phase of moon [deg,%]: 61, 12% * remarks: Calculator(s): Jan Manek

    Updated path location for (791) Ani on April 7, 2000 Path coordinates: Altitude E. Longitude Latitude U.T. star sun o ' " o ' " h m s o o ........ shortened .......................... - 11 0 0 51 7 22 21 22 44 55 -17 - 10 0 0 51 9 48 21 22 52 55 -18 - 9 0 0 51 11 53 21 23 1 54 -18 - 8 0 0 51 13 37 21 23 10 54 -19 - 7 0 0 51 15 2 21 23 19 53 -19 - 6 0 0 51 16 7 21 23 27 53 -20 - 5 0 0 51 16 51 21 23 36 52 -20 - 4 0 0 51 17 16 21 23 44 52 -21 - 3 0 0 51 17 20 21 23 53 51 -21 - 2 0 0 51 17 5 21 24 1 51 -22 - 1 0 0 51 16 29 21 24 10 50 -22 0 0 0 51 15 34 21 24 18 50 -23 1 0 0 51 14 18 21 24 26 49 -23 2 0 0 51 12 43 21 24 34 49 -23 3 0 0 51 10 47 21 24 42 48 -24 4 0 0 51 8 32 21 24 50 48 -24 5 0 0 51 5 56 21 24 58 47 -25 6 0 0 51 3 1 21 25 6 47 -25 7 0 0 50 59 45 21 25 14 46 -26 8 0 0 50 56 9 21 25 22 45 -26 9 0 0 50 52 13 21 25 29 45 -26 10 0 0 50 47 57 21 25 37 44 -27 11 0 0 50 43 20 21 25 45 44 -27 12 0 0 50 38 24 21 25 52 43 -28 13 0 0 50 33 7 21 25 60 43 -28 14 0 0 50 27 29 21 26 7 42 -29 15 0 0 50 21 31 21 26 14 41 -29 16 0 0 50 15 13 21 26 22 41 -29 17 0 0 50 8 33 21 26 29 40 -30 18 0 0 50 1 34 21 26 36 40 -30 19 0 0 49 54 13 21 26 43 39 -30 20 0 0 49 46 32 21 26 50 38 -31 21 0 0 49 38 29 21 26 57 38 -31 22 0 0 49 30 6 21 27 4 37 -32 23 0 0 49 21 22 21 27 11 36 -32 24 0 0 49 12 16 21 27 17 36 -32 25 0 0 49 2 50 21 27 24 35 -33 26 0 0 48 53 2 21 27 31 34 -33 27 0 0 48 42 53 21 27 37 34 -33 28 0 0 48 32 22 21 27 44 33 -34 29 0 0 48 21 30 21 27 50 32 -34 30 0 0 48 10 16 21 27 56 32 -34 31 0 0 47 58 40 21 28 2 31 -35 32 0 0 47 46 43 21 28 9 30 -35 33 0 0 47 34 24 21 28 15 30 -35 34 0 0 47 21 43 21 28 20 29 -35 35 0 0 47 8 40 21 28 26 28 -36 36 0 0 46 55 16 21 28 32 28 -36 37 0 0 46 41 29 21 28 38 27 -36 38 0 0 46 27 20 21 28 43 26 -36 39 0 0 46 12 49 21 28 49 25 -37 40 0 0 45 57 56 21 28 54 25 -37 41 0 0 45 42 41 21 28 59 24 -37 42 0 0 45 27 4 21 29 4 23 -37 43 0 0 45 11 4 21 29 9 22 -38 44 0 0 44 54 43 21 29 14 22 -38 45 0 0 44 37 59 21 29 19 21 -38 46 0 0 44 20 53 21 29 23 20 -38 47 0 0 44 3 26 21 29 28 19 -38 48 0 0 43 45 36 21 29 32 19 -38 ........ shortened .......................... ---------------------------------------------------------------------------- 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-| --------------------------------------------------------------------U---U---

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