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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: 7 Nov 2016
STAR: 2UCAC 43051828
ASTEROID: (2494) Inge

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)

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

-S :  20:36:07
-D1 : 20:37:01.57  ± 0.08 s
-R1 : 20:37:02.21  ± 0.08 s
-D2 : 20:37:04.45  ± 0.08 s
-R2 : 20:37:07.81  ± 0.08 s
-E :  20:37:51

Duration event 1: 0.64 s ± 0.16 s

Duration event 2: 3.36 s ± 0.16 s

TELESCOPE
-Type: Schmidt-Cassegrain, Celestron 11-inch
-Aperture: 280 mm
-Focal length: 930 mm (with focal reducer)
-FOV: about 23x18 arcmin
-Mount: Equatorial
-Motor drive: No

6. TIMING & RECORDING
-Sensor/Camera: Videocamera WAT-910HX/RC, CCIR, 1/2", ICX429ALL sensor
-Videocamera settings: Shutter = x8; Manual Gain = 41/41; Gamma = 1.00
-Device of recording: Personal computer, Imaging Source DFG/SV1 PCI, S video input, Huffyuv compression, Virtualdub software
-Time Insertion Device: IOTA-VTI, v.1.1.42
-Timekeeping: GPS 1PPS
-Integration time: 0.160 s

7. OBSERVING CONDITIONS
Atmospheric transparency: good
Wind: no
Star image stability: fair-good

8. ADDITIONAL COMMENTS
Event predicted by Occultwatcher:
-Feed: IOTA
-Rank: 65
-Predicted event time: 20:36:53 UT
-Predicted error in time: 8 s
-Probability: 0.2 %
-Predicted lightdrop: 2.7 mag
-Predicted max duration: 3.9 s
-Target star: 12.5 magV

Automatic observation: pre-pointing mode.

-Target position: azimut 95 deg, elevation 53 deg.
-Moonphase: 50.4 %.
-Moon distance from target: 99 deg.
-C2A was used to pre-point the target.

-A time correction of -0.100 s was performed because of the use of an integrating camera.
-Lightcurve analysis made by Dr. Raoul Behrend. A graph of the luminosity can be seen here:
http://sposetti.ch/wp-content/uploads/2014/09/2016_11_07_Inge.png

Notes and first analysis:
- Inge is slightly visible during the two events near the noise limit - that explain the very noisy lightcurve during the events.
- The two events are both much deeper then 0.7 mag, ruling out an occultation of a binary star.
- The duration between the beginning of the first event and the ending of the second one is about twice the predicted duration of a central occultation. First rotational lightcurve obtained the coming nights after the events by the CdR-CdL Team ( http://obswww.unige.ch/~behrend/page4cou.html#002494 for full credit) show a rotational period of 0.28 day (to be refined) and an amplitude of 0.15 mag. That seems to exclude a bone-shaped asteroid à la Kleopatra; rest the possibility of a satellite (guessed 80% probability). The relatively small distance between the object using a circular motion as statistical prior conduct to the possibility of mutual events with a depth around 0.1 mag at 1 opposition over 6 - apparently it's not the eclipsing season now. Regular photometric rotational lightcurves observations and further occultation heavy monitoring is a must do for this object.