ASTEROIDAL OCCULTATION - REPORT FORM

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

1 DATE: 2022/08/17
  STAR: UCAC4 391-125809
  ASTEROID: (909) Ulla

2 OBSERVER: Name: Daniel BLAZEWICZ
            Address: 32-015 Klaj, POLAND

3 OBSERVING STATION: Klaj  Nearest city: Niepolomice (Poland)
  Longitude: E 20 19 04.2 (WGS84)
  Latitude:  N 49 59 33.2 (WGS84)
  Altitude:  211 m (MSL)
  Single station

                         +----------------------------+
4 TIMING OF EVENTS:      |                            |
                         |  EVENT REPORTED: NEGATIVE  |
                         |                            |
                         +----------------------------+
  
  Event code
  S: observation Start   I: Interruption start
  D: Disappearance       J: Interruption end
  R: Reappearance        B: Blink   F: Flash
  E: observation End     O: Other (specify)
  
  Abbreviations
  P.E.: Personal Equation = reaction time (for visual obs)
  Acc.: Accuracy (overall accuracy of the given time)
  
                                                  Comments
  Event   Time (UT)    P.E.   Acc.   
  Code   HH:MM:SS.ss   S.ss   S.ss
  
    S  - 21:02:55    -      -      :
    E  - 21:08:52    -      -      :

5 TELESCOPE: Type: NEWTON    Aperture: 350 mm
             Magnification: prime focus f/4.8
             Mount: EQUATORIAL with polar wedge    Motor drive: YES

6 TIMING & RECORDING:
  Time source: "chrony", 4 x NTP Stratum 1, Linux Ubuntu, 1 sigma < 1 ms
  Sensor: ZWO ASI174MM-C
  Recording: ZWO ASICAP V2.3
  Exposure: 500 ms

7 OBSERVING CONDITIONS:
  Atmospheric transparency: fair  Wind: no   Temperature: 21 deg C
  Star image stability: good      Minor planet visible: yes

8 ADDITIONAL COMMENTS:
  Analyzed using Tangra v3.7.4 and AOTA v4.2022.8.18
  S/N of occulted star: 10 - 14 (Tangra)
  Camera temperature: -15 deg C

  Measured expected mag drop: 0.43 mag (Tangra) - 23 minutes before
  predicted occultation the asteroid was 2.05 times brigther than the star.
  
  Observed no drop bigger than 0.35 mag (AOTA) - which was visible only
  on single frame 5 seconds after the predicted occultation.

 IBEROC feed (2022/08/05):
  Event time: 21:05:50 UT
  Error in time: 2 s
  Max duration: 8.6 s
  Star magnitude: 14.4 m
  Asteroid magnitude: 13.9 m
  Combined magnitude: 13.4 m
  Magnitude drop: 0.5 m
  Position: In the shadow, 56 km from the central line
  Probability: 81.4 %