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                ASTERIODAL OCCULTATION - REPORT FORM

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                      EAON & IOTA-ES

              EUROPEAN ASTEROIDAL OCCULTATION NETWORK

   INTERNATIONAL OCCULTATION TIMING ASSOCIATION EUROPEAN SECTION

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1. DATE: 29 dec 2011
   STAR: UCAC2 40143290
   ASTEROID: (198) Ampella

2. OBSERVER
   Name: Stefano SPOSETTI
   Address: 6525 GNOSCA - Switzerland
   Email: stefanosposetti@ticino.com

3. OBSERVING STATION
   Nearest city: CH-6500 Bellinzona
   Longitude: 9d 1m 26.5s E
   Latitude: 46d 13m 53.2s N
   Altitude: 260m

4. TIMING OF EVENTS
   Occultation recorded: POSITIVE
   Type of event:
   "S"tart observation;
   "I"nterrupt-start;
   "D"isappearance;
   "B"link;
   "F"lash;
   "E"nd observation;
   "I"nterrupt-end;
   "R"eappearance;
   "O"ther (specify)

   Personal Equation Substracted: No
   Event Time (UTC)       Accuracy + Comments
   code: HH:MM:SS.ss      S.ss
    -S : 01:56:18
    -D : 01:56:50.77      ± 0.04s
    -R : 01:56:55.61      ± 0.04s
    -E : 01:57:57

   Duration: 4.84s ± 0.08s

5.TELESCOPE:
   Type: Newtonian
   Aperture: 400mm (with focal reducer)
   Focal lenght: 1000mm
   Mount: equatorial
   Motor drive: no

6. TIMING & RECORDING
   Timekeeping: GPS 1PPS (US Global Sat EM-406A)
   Sensor/Camera: Videocamera WAT-902H Ultimate, 1/2" Sony CCD-Sensor ICX429ALL
   Videocamera settings: Gain=HI , Gamma=HI
   Device of recording: Personal computer, TV-AV PCI-TV7130, S-video input,
   Virtualdub software, saved on Harddisk
   Mode of recording: Integration time=0.04s (25 Img/s), CCIR, Huffyuv
   Time insertion device: IOTA-VTI, v.1.1.42

7. OBSERVING CONDITIONS
   Atmospheric transparency: good
   Wind: no
   Star image stability: good
   Minor Planet Visible: yes

8. ADDITIONAL COMMENTS
   Accordingly to Occultwatcher:
   -Predicted event time: 01:56:58UT
   -Predicted combined luminosity: 10.9mag
   -Predicted luminosity drop: 0.5mag
   -Predicted max duration: 6.6s
   -Probability of a positive event in Gnosca: 62%

Automated observation. The telescope was pre-pointed to the target position.
Limovie software was used to analyze the AVI files. A 0.5mag drop was measured.
The lightcurve of the event is here:
http://www.sposetti.ch/images/stories/Minor_planets/2011_12_29_(198)Ampella_Gnosca.png