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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: 30 Nov 2017
   STAR: 4UC 543-025637
   ASTEROID: (50) Virginia

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

3. OBSERVING STATION
   Nearest city: CH-6525 Gnosca
   Longitude: 9d 1m 26.5s (E)
   Latitude: 46d 13m 53.2s (N)
   Altitude: 260m
   (WGS84)

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: -
   Event Time (UTC) Accuracy + Comments
   code: HH:MM:SS.ss S.sss

-S : 20:10:10
-D : 20:15:27.61 ± 0.64 s
-R : 20:15:32:09 ± 0.64 s
-E : 20:20:30

   Duration: 4.48 s ± 1.28 s

5. TELESCOPE
   -Type: Schmidt-Cassegrain, Celestron 11-inch
   -Aperture: 280 mm
   -Focal length: 930 mm (with focal reducer)
   -Magnification: FOV 23x18 arcmin
   -Mount: Equatorial
   -Motor drive: Yes

6. TIMING & RECORDING
   -Sensor/Camera: Videocamera WAT-910HX-RC, CCIR, 1/2", ICX429ALL sensor
   -Videocamera settings: Shutter = x16; Gain = 38/41; Gamma = 1.00
   -Device of recording: Personal computer, Imaging Source DFG/SV1 PCI, composite input, Virtualdub acquiring software, saved on Harddisk as uncompressed file
   -Timekeeping: GPS 1PPS (US Global Sat EM-406A)
   -Time insertion device: IOTA-VTI, v.1.1.42
   -Integration time: 0.320 s
  
7. OBSERVING CONDITIONS
   -Atmospheric transparency: good, Moonlight
   -Wind: none 
   -Star image stability: fair
   -Minor Planet Visible during the occultation: yes

8. ADDITIONAL COMMENTS
   -Target position: elevation = 25 deg; azimut = 88 deg.
   
   Accordingly to Occultwatcher prediction, IBEROC feed:
   -Rank: 98
   -Probability: 22.2 %
   -Combined magnitude: 11.9 mag
   -Star magnitude: 13.5 mag R; 13.9 mag V
   -Asteroid magnitude: 12.2 mag
   -Lightdrop: 0.29 mag; 0.2 mag R
   -Max duration: 13 s
   -Event time: 20:15:37 UT
   -Error in time: 5 s
   -Moon distance: 64 deg
   -Moon illumination: 89 %

   -An high signal was achieved with defocused images.
   -Tangra v. 3.6.13 was used to generate the lightcurve (aperture photometry, average background).
   -The lightcurve was binned from the original 8 frames (0.320 s) to 32 frames (1.28 s).
   -A correction of -0.660 s was applied because of the use of an integration camera.
   -Measured lightdrop: 0.24 mag. (Intensity drop from 5600 to 4500).
   -A lightcurve can be seen here:
   http://sposetti.ch/wp-content/uploads/2014/09/20171130_Virgina_2.png