Observation by Alex Pratt: (2111) Tselina occults UCAC4 491-028819

Uploaded by

Alex Pratt

Observer

Alex Pratt

Observed

2018 Dec 24 - 21:52

Uploaded

2018 Dec 25 - 21:33

Objects

Conjunction

Equipment

C11 f/10 and f/3.3 focal reducer
Watec 910 video camera
IOTA-VTI GPS time inserter
OccuRec (recording)
Tangra and AOTA (reduction)

Exposure

0.16s (4 integrated video frames)

Location

Z92

Target name

Asteroid (2111) Tselina occults star UCAC4 491-028819

Title

(2111) Tselina occults UCAC4 491-028819

About this image

The mag 14.5 27 km diameter asteroid (2111) Tselina was predicted to occult the mag 12.4 star UCAC4 491-028819 on 2018 December 24. Their combined magnitude would drop by 2.3 mag for up to 2.2 seconds.

My observatory was 1 km inside the predicted shadow zone. The predicted probability of success at my site was 21.1% and I recorded an occultation duration of 0.96s. The times of disappearance and reappearance were:-

D 21 52 25.87 +/- 0.08s

R 21 52 26.83 +/- 0.08s

The attached plot shows the analysis of the light curve using Tangra and AOTA software. No other observers were registered for this event, so we can't derive a shape profile, but a single positive observation can give high quality astrometry at the instant of the occultation.

Files associated with this observation

2018-Dec-24 21-52-01 (185) 5 B95 C10 pix_Bin1_Form.png (79.0 kB)

Like this image

Jeremy Shears, Ray Emery, David Swan, Mr Leonard Entwisle, Neil Morrison, Eric Watkins, Graham Winstanley, Andy Wilson, David Basey, Peter Carson

Comments

Ray Emery, 2018 Dec 26 - 00:37 UTC

Alex - brilliant! Well done that man! :-)

- Ray E. -

Alex Pratt, 2018 Dec 26 - 12:14 UTC

Thanks Ray.

The occultation of the star occurred within the prediction uncertainty of 4s, so we have to assume that it was caused by the asteroid rather than high flying reindeer...

Star positions are known to great accuracy thanks to the Gaia project, although asteroids' orbits are not (yet) to that level. The uncertainties of predictions of asteroidal occultations are much smaller than they were years ago. The later Gaia Data Releases should allow us to compute good quality predictions but the weather across our Misty Isles will continue to thwart many efforts to observe them.

Copyright of all images and other observations submitted to the BAA remains with the owner of the work. Reproduction of work by third parties is expressly forbidden without the consent of the copyright holder. By submitting images to this online gallery, you grant the BAA permission to reproduce them in any of our publications.

Registered charity no. 210769
Registered company no. 117572

For more information including contact details, click here.

Our Terms of Use are here.

Our Privacy Policy is here.