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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: 31 Aug 2021
   STAR: UCAC4 505-012002
   ASTEROID: (489) Comacina

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 : 01:27:30
-D : 01:30:27.63 ± 0.05 s
-R : 01:30:27:88 ± 0.05 s
-E : 01:33:30

   Duration: 0.25 ± 0.10 s

5. TELESCOPE
   
   -Type: Newton
   -Aperture: 420 mm
   -Focal length: 1640 mm
   -Mount: Equatorial
   -Motor drive: Yes

6. TIMING & RECORDING
   
   -Camera/Sensor: Videocamera  QHY174M-GPS, SONY IMX174 CMOS sensor
   -Device of recording: personal computer, USB3 input, SharpCap PRO v. 3.2.6173.0 software, saved on SSD as SER file
   -binning = 2x2, sensor uncooled, camera bit depth = MONO16, area size in pixel = 960x600, USB traffic = 5, setted exposure = 100 ms, gain = 480, offset = 0, contrast = 0, brightness = 0, gamma = 1, banding suppression = 0, banding threshold = 35, apply flat = none, subtract dark = none
   -Timekeeping: GPS UTC clock
   -Integration time: 0.100 s
 
7. OBSERVING CONDITIONS
   
   -Atmospheric transparency: fair/good, moonlight
   -Wind: no 
   -Star image stability: fair/good
   -Minor Planet visible during the occultation: -

8. ADDITIONAL COMMENTS
   
   Prediction:
   -Occultwatcher, IOTA feed
   -Rank: 100
   -Probability: 14.3 %
   -Combined magnitude: 12.2 mag
   -Star magnitude: 11.9 mag V; 11.7 mag R
   -Asteroid magnitude: 14.5 mag
   -Lightdrop: 2.33 mag
   -Max duration: 5.9 s
   -Event time: 01:30:28 UT
   -Error in time: 1 s
   -Moon distance: 14 deg
   -Moon illumination: 43 %

   Other comments:
   -Target sky position: elevation = 21 deg, azimut = 96 deg
   -Tangra v. 3.7.3 was used to generate the lightcurve (aperture photometry, median background). Time reference: Start Frame 
   -The event is evident during two integration frames
   -Measured mid-event time: 01:30:27.75 UT   
   -The lightcurve can be seen here:
http://sposetti.ch/wp-content/uploads/2021/08/2021_08_31_Comacina_Gnosca.png