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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: 04 FEB 2013
   STAR: 3UC186-060995
   ASTEROID: (5263) Arrius

2. OBSERVER
   Name: Stefano SPOSETTI
   Address: CH-6525 GNOSCA
   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
   (WGS84)

4. TIMING OF EVENTS
   Occultation recorded: NEGATIVE
   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 : 20:02:12
    -D :
    -R :
    -E : 20:06:21

5. TELESCOPE:
   Type: Newtonian
   Aperture: 400mm
   Focal length: 930mm (with focal reducer)
   Magnification: FOV 23x18arcmin
   Mount: equatorial
   Motor drive: yes

6. TIMING & RECORDING
   Timekeeping: GPS 1PPS (US Global Sat EM-406A)
   Sensor/Camera: Videocamera WAT-120N+, CCIR, 1/2" Sony CCD-Sensor ICX419ALL
   Videocamera settings: Shutter mode SLOW=2, Gain=max, Gamma=OFF
   Device of recording: Personal computer, Hauppage HVR-1700(PCI), S-video input
   Virtualdub software, saved on Harddisk
   Mode of recording: Integration time=0.080s, 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: no

8. ADDITIONAL COMMENTS
The predicted event time from my location was 20:04:04UT ± 12s with a max. duration of 2.2s and an intensity drop of 6.7mag (accordingly to Occultwatcher).
The lightcurve delivered by Tangra shows no lightdrop to zero intensity, but a small intensity drop from the mean level of 812 (calculated on the 100 preceding points and on the 100 following points) (with a standard deviation of 98) to 457 was noticed. The 3 used reference stars didn't show a similar drop of light at the same instant.
The measured central time (corrected with the G. Dangl correction table) of this lightdrop was:
20:04:06.89 UT with a duration of one integration interval, ie. 0.080s.

Because no evident lightdrop was detected, I judge this occultation as negative.

A lightcurve can be seen here:
http://sposetti.ch/images/stories/Minor_planets/2013_Feb_4_Arrius.png