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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 : 04/12/2009
 STAR : 3UC211-040536
 ASTEROID : (52) Europa

2.OBSERVER:
Name: Stefano SPOSETTI
Address: CH-6525 Gnosca, Switzerland
E-mail: stefanosposetti@ticino.com

3.OBSERVING STATION:
Nearest city: CH-6500 Bellinzona
Station: Gnosca Observatory
Latitude: 46deg 13min 54sec (N)
Longitude: 9deg 1min 30sec (E)
Altitude: 260 m
Single/Multiple: single

5.TELESCOPE:
Type: Newtonian
Aperture: 40cm f/4
Magnification: -
Mount: equatorial
Motor drive: yes

6.TIMING & RECORDING:
        Occultation recorded:   POSITIVE
        Personal Equation Substracted: No because of electronic timing
        Event Time in UT
        Code:        HH:MM:SS.ss  S.ss
        Code:        HH:MM:SS.ss  S.ss
        S            22:49:35
        D            22:52:09.45 ± 0.1s
        R            22:52:42.01 ± 0.1s
        E            22:55:20
Duration of the occultation: 32.56s ± 0.2s

Timekeeping: via Computer ("Dimension4" software)
Mode of recording: CCD drift-scan ("Winscan 207" software)
Device of recording:  CCD (SBIG ST8XME)

7.OBSERVING CONDITIONS:
Atmospheric transparency: good
Wind: none at the observatory
Star image stability: fair-poor (some high altitude wind)
Driftscan speed at 0.01s/pixel
Sampling: 1.2arcsec/pixel
FWHM of stars: 7arcsec

8. NOTES:

Before the scheduled event, both star and the approaching asteroid were easily
visible in CCD pictures.
With a 0.01s/pixel sampling I obtained a good trace of the 10.5magR (star) +
10.4mag (asteroid) in the CCD drift scan.
The moonlight (Moon about 20deg far away) was not disturbing.
The poor seeing led to 7arcsec FWHM stars.
The uncertainty of the absolute time precision is limited to 0.07s, rounded to 0.1s.
The uncertainty of the duration was computed from the midpoint of the descendig
"wing" to the ascending "wing".
The computer clock was controlled by the D4 software. During the run
the maximum shift between computer-clock and SNTP-reference-clock was 0.026s (15
minutes syncronization time interval was used).
I placed an image of the scan here:
http://web.ticino.com/sposetti/Europa_Occultation.JPG

Also a parallel C8 telescope equipped with a Watec 902H video camera was used.
The photometric analysis of the frames (Limovie software) do not show any
luminosity drop, probably because of the poor SNR.

This is the 5th positive occultation from my observatory since 2000.