+--------------------------------+ +--------------------------------+

                ASTERIODAL OCCULTATION - REPORT FORM

+--------------------------------+ +--------------------------------+

                      EAON & IOTA-ES

              EUROPEAN ASTEROIDAL OCCULTATION NETWORK

   INTERNATIONAL OCCULTATION TIMING ASSOCIATION EUROPEAN SECTION

+--------------------------------+ +--------------------------------+


1. DATE: 03 MAY 2011 
   STAR: TYC 1934-01049-1
   ASTEROID: (42) Isis

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

3. OBSERVING STATION
   Nearest city: CH-6500 Bellinzona
   Longitude: 46deg 13min 53.2sec (N)
   Latitude: 9deg 1min 26.5sec (E)
   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 : 22:07:00
    -D : 22:09:15.667 (+/-0.170)
    -R : 22:09:17.587 (+/-0.170)
    -E : 22:13:00
Duration: 1.92s (+/-0.34)

5. TELESCOPE
   Type: Schmidt-Cassegrain, Celestron
   Aperture: 280mm
   Focal length: 930mm (with focal reducer Optec 0.33X)
   Magnification: FOV 23x18arcmin
   Mount: Equatorial
   Motor drive: Yes

6. TIMING & RECORDING
   Timekeeping: KIWI-OSD with GPS Garmin 18 LVC
   Sensor/Camera: Videocamera WAT-120N+, CCIR, 1/2" Sony CCD-Sensor ICX419ALL
   Videocamera settings: Shutter mode=Slow4, Gain=HI , Gamma=LO
   Device of recording: Personal computer, Imaging Source DFG/SV1 PCI, S-video,
   Virtualdub software, saved on Harddisk
   Mode of recording: Integration time=0.320s, CCIR, Huffyuv
   Time insertion: KIWI-OSD

7. OBSERVING CONDITIONS
   Atmospheric transparency: fair
   Wind: some wind in the observatory
   Star image stability: fair
   Minor Planet Visible: no

8. ADDITIONAL COMMENTS
Sky transparency was initially poor. The target star was barely visible in the 0.32s integration time of the videocamera. Two minutes before the event, the sky "cleared". From that moment the target star was clearly visible on the screen.
To the naked eye the limiting magnitude of zenit stars was about 4.

Virtualdub was used to read the timings of the event. Tangra was used to plot the intensity of light versus time and to isolate the light drop.

Because of the use of a WAT-120N+ in integration mode Slow4 (Integration time=320ms) a correction of -190ms was made to the video inserted times according to the correction table here:
http://www.dangl.at/ausruest/vid_tim/vid_tim1.htm#wat120+ccir

According to OccultWatcher, my station was 6km outside the 1 sigma zone , with a probability of a positive event of 13.7%.

A still image is here:
http://sposetti.ch/images/stories/Minor_planets/42_Isis_03may2011.png