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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: 16 Dec 2022
   STAR: UCAC4 429-043035
   ASTEROID: (24749) Grebel

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: 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 - 21:20:30
D - 21:23:40.27 ± 0.10 s
R - 21:23:41.27 ± 0.10 s
E - 21:26:30

   Duration: 1.00 ± 0.14 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. 4.0.9268.0 software, saved on SSD as ADV file
   -binning = 2x2, sensor uncooled, camera bit depth = MONO16, area size in pixel = 960x600, USB traffic = 5, setted exposure = 200 ms, gain = 480, offset = 0, contrast = 0, brightness = 0, gamma = 1, banding suppression = 100, banding threshold = 40, apply flat = none, subtract dark = none
   -Timekeeping: GPS UTC clock
   -Integration time: 0.200 s

7. OBSERVING CONDITIONS
   
   -Atmospheric transparency: fair/good
   -Wind: no 
   -Star image stability: fair
   -Minor Planet visible during the occultation: no

8. ADDITIONAL COMMENTS
   Prediction:
   -Occultwatcher, CentralEurope
   -Rank: 30
   -Probability: 17.6 %
   -Combined magnitude: 13.6 mag
   -Star magnitude: 11.2 magV; 11.0 magR
   -Asteroid magnitude: 18.9 mag
   -Lightdrop: 7.7 mag
   -Max duration: 1.8 s
   -Event time: 21:23:35 UT
   -Error in time: 5 s
   -Moon distance: -
   -Moon illumination: -
   -https://cloud.occultwatcher.net/event/714-24749-115840-647722-U043035

   Other comments:
   -Target sky position: elevation = 11 deg, azimut = 108 deg
   -Tangra v. 3.7.4 was used to generate the lightcurve (aperture photometry, average background).
   -AOTA v. 4.2022.11.10 was used to extract D and R times
   -SnR = 7.3
   -Many thanks to Eric Frappa who checked the analysis
   -The lightcurve can be seen here:
https://sposetti.ch/wp-content/uploads/2022/12/2022_12_16_Grebel_Gnosca.png