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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 Jun 2021
   STAR: TYC 6273-01107-1
   ASTEROID: (2357) Phereclos

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 : 23:05:10
-D : 23:06:37.98 ± 0.20 sec
-R : 23:06:42.05 ± 0.30 sec
-E : 23:07:38

   Duration: 4.07 ± 0.36 sec

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

6. TIMING & RECORDING

   See paragraph 8.
 
7. OBSERVING CONDITIONS
   
   -Atmospheric transparency: good
   -Wind: no 
   -Star image stability: fair/good
   -Minor Planet visible during the occultation: -

8. ADDITIONAL COMMENTS
   
   Prediction:
   -Occultwatcher, IOTA feed
   -Rank: 100
   -Probability: 16.9 %
   -Combined magnitude: 11.2 mag
   -Star magnitude: 11.2 mag V
   -Asteroid magnitude: 15.8 mag
   -Lightdrop: 4.62 mag
   -Max duration: 6.27 s
   -Event time: 23:06:36 UT
   -Error in time: 4 s
   -Moon distance: 86 deg
   -Moon illumination: 59 %

   Other comments:

   -Camera/Sensor: Videocamera  QHY174M-GPS, SONY IMX174 CMOS sensor
   -Device of recording: personal computer, USB3 input, SharpCap PRO v. 3.2.6173.0 software
   -binning = 2x2, sensor uncooled, camera bit depth = MONO16, area size in pixel = 960x600, USB traffic = 5, setted exposure = 50 ms, gain = 480, offset = 0, contrast = 0, brightness = 0, gamma = 1, banding suppression = 0, banding threshold = 35
   -Timekeeping: GPS UTC clock
   -Integration time during the acquiring: 0.050 s
   -Target sky position: elevation = 23 deg, azimut = 166 deg
   -Unfortunately there is no SER file of the occultation because I did not clicked on the REC button. However I recorded a (low quality) live printscreen of the event in MKV format. In this movie the occultation is more or less clearly visible.
   -From this MKV file an AVI file was created with Virtualdub.
   -My location was positioned in the 1-sigma zone of the ground track prediction. Accordingly to OW, no other positive or negative reports were made from positions near my chord. Because of that, the analysis of the event was done.
   -D and R times and their uncertainties were extracted by Eric Frappa from a selected portion of the printscreen movie, using the timestamps visible on the frames.
   -Tangra v. 3.7.3 was used to generate the lightcurve (aperture photometry, average background).
   -Measured mid-event time: 23:06:40 UT.
   -Many thanks to Eric Frappa for the appreciated help.
   -The lightcurve can be seen here:
http://sposetti.ch/wp-content/uploads/2021/06/2021_06_18_Phereclos_Gnosca.png