<p>The IAU Minor Planet Center lists <span class="math-container">$(486958)\space 2014 \space MU_{69}$</span> "Ultima Thule" as having an uncertainty parameter of 2, based on the observation arc of 851 days, from its discovery in 2014, to the last observation submitted from Hubble in 2016.</p>

<p><a href="https://en.wikipedia.org/wiki/(486958)_2014_MU69#2017_occultations" rel="noreferrer">Other</a> <a href="https://en.wikipedia.org/wiki/(486958)_2014_MU69#2018_occultations" rel="noreferrer">sources</a> indicate that there have been a number of ground-based observations of Ultima Thule occulting various background stars. Are these "observations" purposely not included/submitted as further sightings to increase the observation arc?</p>

CC BY-SA 4.0
2019-06-07T21:56:17.400Z
Have a look at [this answer](https://space.stackexchange.com/a/34094/12102) to *Does JPL's Horizons have better MU69 state vectors for the New Horizons flyby somewhere?*
uhoh
CC BY-SA 4.0
2019-06-13T04:07:31.490Z
This doesn't directly answer the question, but [Porter et al. 2018](https://arxiv.org/abs/1805.02252) tell how they determined 2014 MU69's orbit well enough to predict occultations.
Mike G
<observational-astronomy><orbital-elements><dwarf-planets><occultation><trans-neptunian-object>
Are occultation observations used/useful for orbit determination?
costrom
# Are occultation observations used/useful for orbit determination?

(Asked by: username_0 on 2019-06-07)

The IAU Minor Planet Center lists $(486958)\space 2014 \space MU\_{69}$ "Ultima Thule" as having an uncertainty parameter of 2, based on the observation arc of 851 days, from its discovery in 2014, to the last observation submitted from Hubble in 2016.

[Other](https://en.wikipedia.org/wiki/(486958)_2014_MU69#2017_occultations) [sources](https://en.wikipedia.org/wiki/(486958)_2014_MU69#2018_occultations) indicate that there have been a number of ground-based observations of Ultima Thule occulting various background stars. Are these "observations" purposely not included/submitted as further sightings to increase the observation arc?

**Tags:** observational-astronomy, orbital-elements, dwarf-planets, occultation, trans-neptunian-object

> **Comments:**
> **username_1**: Have a look at [this answer](https://space.stackexchange.com/a/34094/12102) to *Does JPL's Horizons have better MU69 state vectors for the New Horizons flyby somewhere?*  
> **username_2**: This doesn't directly answer the question, but [Porter et al. 2018](https://arxiv.org/abs/1805.02252) tell how they determined 2014 MU69's orbit well enough to predict occultations.  

---

## 0 answers

