Occultation by 40 Harmonia

Observed: 12 Nov 2007

Michel Bonnardeau
12 Nov 2007
revided 28 Dec 2007 (GPS time uncertainty)
corrected 10 Apr 2017 (shadow size)

Abstract

The minor planet 40 Harmonia was observed occulting a 10.6 mag star. The duration of the occultation was 3.2±0.4s.

Observation

The occultation of mag 10.6 star TYC6355-01269-1 by the asteroid 40 Harmonia on 12 Nov 2007 UT in the vicinity of my location was predicted by S. Preston: http://www.asteroidoccultation.com/2007_11/1112_40_9183.htm.

The observation was carried out with a 203mm f/6.3 SC telescope, a Clear filter and a SBIG ST7E camera (KAF401E CCD). The conditions were poor with clouds and a bad seeing. The exposure was 60s long, starting at 19:04:54 TU: I let the telescope tracks for about 10s, then I switched off the RA drive.

I estimate the uncertainty on the time with my NMEA GPS as 2s (I compared with the French Horloge Parlante 3699). Futhermore, MaximDL3 records the time to the nearest second. The total uncertainty on the timing of the beginning of the occultation is then +/-2.5s.

A part of the resulting image is:


1: the occulted star at the beginning of the exposure;
2: the beginning of the occultation;
3: its end;
4: the occulted star at the end of exposure.

My image is 0.294° and 765 pixels width. The angular distance between 2 and 4 is 6.633'+/-4pixels or 26.5+/-0.4s, then the beginning of the occultation 2 is at 19:05:27.5 +/- 2.9 UT. The angular distance between 2 and 3 is 48.3"+/-4pixels and the duration of the occultation is 3.2+/-0.4s.

Technical notes

Telescope and camera configuration.

Computer and software configuration.