ASTEROIDAL OCCULTATION - REPORT FORM- CORRECTIF 1

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

1 DATE: 2019 July 11              STAR: UCAC4 311-163008

  ASTEROID: 257 SILESIA          

2 OBSERVER: Name:  Gérard VAUDESCAL           Abbr:VDC
            E-mail: gg.vaudescal@free.fr
            Address: 65380 Azereix - France

	    Name:   Pascal DUBARRY            Abbr:
	    E-mail:
	    Address: ASS. DINASTRO


3 OBSERVING STATION: Nearest city: VISKER(65200)
  Station: Observatoire de Biscarmiau
  Latitude:  N 43 08 40.4 (WGS84)
  Longitude: E 00 03 31.8 (WGS84)
  Altitude: 488 m

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

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

                                                  Comments
  Event   Time (UT)   	 Acc.   
  Code   HH MM SS.ss  	 S.ss
  
    S  - 21:43:07.75     	on frame n°18    (correction Gerhard Dangl)
    D  - 21:43:43.62	+/-2.56s   frame n°33             "
    R  - 21:43:50.02	+/-1.28s   frame n°35 -0/+1       "
    E  - 21:44:19.43 	        on frame n°46		  "
  
  Duration : 	6.4s   +/-2.86sec		 Mid-event : 21:43:46.82 +/-1.9s

  Was your reaction time applied to the above timings? NO

5 TELESCOPE: Type: NEWTON          Aperture: 305 mm        Magnification: Focus 1188 mm
             Mount: Equatorial          Motor drive: YES

6 TIMING & RECORDING: 
  Time source: GPS 1 PPS 
  Sensor: CAMERA WATEC 910HX/RC CCIR -  integrated Shutter Low x128 (2,56sec/f) - Gamma 1 -     Gain Mid
  Recording: OccuRec V 3.2.0 Beta and Grabber Lindy USB2 - mode AAV - Intégration rate x64
  Time  insertion (specify):IOTA VTI V3 (CCIR)
  Event insertion (specify): PC-Windows7

7 OBSERVING CONDITIONS: partly overcast      Wind: 0 ms       Temperature: 15 °C
  Star image stability: medium        Minor planet visible: Yes

8 ADDITIONAL COMMENTS: Reduction under TANGRA 3.6.18 
The conditions of this observation required a significant exposure time. Nevertheless, the luminous flux clearly indicates an occultation but with a low accuracy of dating. There is also a significant lag of the event compared to the forecast: 21:43:46.82 +/-1.9s for a forecast of 21:43:28 +/-4s.
An incident Occurec need a recovery of the dates directly on the video fields with non automatic application of the corrections.