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ASTEROIDAL 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: 18 Dec 2020
   STAR: UCAC4 637-038898
   ASTEROID: (356) Liguria

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

3. OBSERVING STATION
   
   Nearest city: CH-6525 Gnosca
   Station: 143 (MPC-code)
   Longitude (DD MM SS.s): 09 01 26.5 (E)
   Latitude (DD MM SS.s): 46 13 53.2 (N)
   Altitude: 260 m
   (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 : 04:17:00
-D : 04:20:53.08 ± 0.16 s
-R : 04:21:09.00 ± 0.72 s
-E : 04:23:38

   Duration: 15.92 ± 0.74 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 = 41/41; Gamma = 1.00
   -Device of recording: Personal computer, Imaging Source DFG/SV1 PCI, composite input, Virtualdub acquiring software, saved on Harddisk as compressed Lagarith 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
   -Wind: none 
   -Star image stability: fair
   -Minor Planet visible during the occultation: yes

8. ADDITIONAL COMMENTS
   
   Prediction:
   -Occultwatcher, UKOCL feed
   -Rank: 97
   -Probability: 75.2 %
   -Combined magnitude: 10.7 mag
   -Star magnitude: 12.7 mag V; 12.1 mag R
   -Asteroid magnitude: 10.9 mag
   -Lightdrop: 0.2 mag
   -Max duration: 19.1 s
   -Event time: 04:20:43 UT
   -Error in time: 8 s
   -Moon distance: -
   -Moon illumination: -

   Other comments:
   -Target sky position: elevation = 49 deg, azimut = 277 deg
   -Tangra v. 3.7.3 was used to generate the lightcurve (aperture photometry, average background)
   -D and R times were evaluated using AOTA v4.10.5.0, applied confidence level: D = 90 %, R = 90 % 
   -Camera delays have been manually applied (so called "Dangl-correction")
   -Measured mid-event UT time: 04:21:01.0
   -Measured lightdrop: from ~ 13800 ADU to ~ 11600 ADU, ie. ~ 0.2 mag
   -SN at event locations: D: 2.3; R: 2.1; Ave: 2.2
   -A lightcurve can be seen here:
http://sposetti.ch/wp-content/uploads/2020/12/2020_12_18_Liguria_Gnosca.png