ASTEROIDAL OCCULTATION - REPORT FORM

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

1 DATE: 23 September 2018                 STAR: UCAC4 461-131617   

  ASTEROID:  (2875)              N?:  Lagerkvist


2 OBSERVER: Name:  Peter Tickner               Abbr:
            E-mail: xxxxxxxxxxxxxxxxxxxxxx
            Address: xxxxxxxxxxxxxxxxxxxxx

3 OBSERVING STATION: Nearest city: Reading
  Station:Fixed
  Latitude: N 51 25' 33.8"
  Longitude:W 00 55' 14.5"
  Altitude: 44m
  Datum (WGS84 preferred): WGS84

  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)    P.E.   Acc.   
  Code   HH MM SS.ss   S.ss   S.ss
  
    S  - 22:02 01.00 -      -      :		20 frames per second
       -             -      -      :
    D  - 22:04 18.21 -    +/- 0.04 :
    R  - 22:04 18.76 -    +/- 0.06 :
       -             -      -      :
    E  - 22:06 02.00 -      -      :
  
                          Duration : 0.55 s  (+/- 0.1)
                         Mid-event : 22:04 18.49 (+/- 0.1)

  Was your reaction time applied to the above timings? n/a

5 TELESCOPE: Type:  SCT         Aperture:  300mm      Magnification: f/3.3 reducer
             Mount: Equatorial        Motor drive: Yes

6 TIMING & RECORDING:
  Time source: GPS (stratum 1 device TimeBox (Standard version) controlling laptop time)
  Sensor: ZWO ASI174MM CMOS on maximum gain recorded on solid state drive i7 Windows 7 laptop
  Recording:
  Time  insertion (specify): Based on start and end times of SER recording
  Event insertion (specify):

7 OBSERVING CONDITIONS:
  Atmospheric transparency: Good     Wind: Light   Temperature: 9C
  Star image stability: Poor         Minor planet visible: No

8 ADDITIONAL COMMENTS: 
	This was an unexpected result.  Instead of a complete disappearance at the time expected
 there is a partial disappearance some eighteen seconds later.  My data was very noisy and I had missed this until 
 Tim Haymes spotted a similar incident with his data.
   Test of GPS system controlling laptop time 
  at 100fps showed +/- 0.01 seconds from actual time pulse with the norm fractionally ahead of GPS.