ASTEROIDAL OCCULTATION - REPORT FORM

    +------------------------------+  +------------------------------+
    |            EAON              |  |            IOTA/ES           |
    |                              |  |   INTERNATIONAL OCCULTATION  |
    |     EUROPEAN  ASTEROIDAL     |  |      TIMING  ASSOCIATION     |
    |     OCCULTATION NETWORK      |  |       EUROPEAN SECTION       |
    +------------------------------+  +------------------------------+

1 DATE: 20 September 2021             STAR: TYC 3565-01175-1  (10.5 mag)
  ASTEROID: 2008 YB3                      No: 342842

2 OBSERVER: Name: Marek Zawilski            Abbr:
            E-mail: marek.zawilski@p.lodz.pl
            Address: ul.Julianowska 5/7 m.322, 91-473 Lodz, Poland

3 OBSERVING STATION: Nearest cities: Lodz and Poddebice
  Station: Tobolice
  Latitude:  51d 54' 48.3" N
  Longitude: 19d 03' 22.4" E
  Altitude:  140m MSL
  Datum (WGS84 preferred): WGS84

  Single, OR Double or Multiple station (Specify observer's name):
  SINGLE

                         +----------------------------------+
4 TIMING OF EVENTS:      |                                  |
                         |  OCCULTATION RECORDED: NEGATIVE  |
                         |                                  |
                         +----------------------------------+
  Type of event
  Start observation   Interrupt-start   Disappearance   Blink   Flash
  End observation     Jnterrupt-end     Reappearance    Other (specify)

                                                  Comments
  Event   Time (UT)    P.E.   Acc.   
  Code   HH:MM:SS.ss   S.ss   S.ss
  
    S  - 22:18:24    - N/A  - 1    :
    I  - 22:18:50    - N/A  - 1    :
    J  - 22:19:03    - N/A  - 1    :
    I  - 22:19:21    - N/A  - 1    :
    J  - 22:19:26    - N/A  - 1    :
    D  -   -                       :  
    R  -   -                       :   
    E  - 22:29:40    - N/A  - 1    :
  
                          Duration : no occultation 
                         Mid-event : (20 Sep; 22:29:05) i.e. 10s earlier than predicted according to the positive observation by M.Harman
               Predicted mid-event : 20 Sep.; 22:29:15 UT  +/- 27 sec

  Was your reaction time applied to the above timings? N/A

5 TELESCOPE: Type: Cassegrain       Aperture: 203mm    Magnification: ---
             Mount: Equatorial     Motor drive: YES   Foc.length: 2032mm reduced to 1016mm

6 TIMING & RECORDING:
  Time source: Laptop time controlled by the GPS TimeBox device (time error 0.000 s).
  Sensor: ZWO ASI 120MM, shutter set for 500 ms, image resolution 1024x768 px, gain 60.
  Recording: SHARPCAP v.3.2.6383.0 software

7 OBSERVING CONDITIONS:
  Atmospheric transparency: good but with passing thin clouds          Wind: none            Temperature: +5 deg C
  Star image stability: good within periods without clouds             Minor planet visible: no

8 ADDITIONAL COMMENTS:
 
The light curve analyze using Tangra software and a careful inspection of the screen replay showed no longer remarkable rapid drop of the star brightness caused by the asteroid. The star image was not stable enough for the occulted star because of passing thin clouds; however, because the star was detectable on the recording in the periods stated above, there was no occultation longer than 0.5s and the observation has been classified as negative.

  Predicted max 1.9 sec duration with 10.6 mag drop.
  Event probability at site : 6.0 %
  Distance from center line : 210.5 km in 344° direction, outside the predicted path, inside the 1-sigma limit
  Local * conditions (Alt,Az): 54°, @290° in Cygnus
  Moon (Alt,Az): 33°, @174°, near full moon but did not disturbe the star view.