Murrili’s timed trail to Kati Thanda

William Creek · camera view — E. K. Sansom and coauthors / Desert Fireball Network, Curtin University. Associated study: Sansom et al. (2020).
Event image. William Creek’s all-sky photograph of the 27 November 2015 fireball. The trail spans successive positions during a long exposure. Unchanged 1632 × 1080 camera-embedded JPEG preview; no new RAW reduction or calibration. The source file clock reads 10:43:28, separate from the study’s event-onset time. The original-image link opens the large NEF archive source.
CC BY 4.0 · author archive licence; credited camera-embedded preview retained unchanged. Source research cited.
· Original image source · Image licence

Follow the broken trails in the all-sky photographs, then examine the gap between the last visible light and the recovered rock. How much of that journey was measured?

World: Earth
Location: Australia
Case date or period: 27 November 2015

Follow the dashes across the sky

Look along the broken trails in the station photographs: the gaps carry timing information as well as a record of light. Sansom and colleagues report a 6.1-second fireball beginning at 10:43:45.526 UTC on 27 November 2015. Ten Desert Fireball Network observatories recorded it across South Australia. The cameras used long exposures, while a liquid-crystal shutter encoded a repeating timing sequence along each trail. A single all-sky exposure therefore contains successive positions; it is not a movie frame or evidence of several simultaneous objects.

From pixels to a trajectory

The authors calibrated camera directions against stars and triangulated observations from different stations. Their paper distinguishes measured image directions from a fitted atmospheric trajectory. It also notes saturation and the effects of station distance on precision. The final analysis estimates entry speed near 13.68 kilometres per second and follows the luminous flight down to about eighteen kilometres altitude. The photographic endpoint ends the visible record. It does not show where the surviving material finally touched the ground.

The observations remain separate products

The author-deposited image archive contains four raw camera files from Billa Kalina, William Creek, Wilpoorina and Etadunna. Their station identities describe viewpoints, rather than four fall locations. The archive was published in June 2020, years after the November 2015 exposures, and asks users to cite the associated research. Keeping this chain visible lets readers distinguish a raw station image from a cropped or annotated presentation. Its file timestamp should not be silently substituted for the first luminous-flight time reported in the trajectory analysis. This gallery shows three unchanged camera previews, rather than a RAW reduction. The fourth archive preview was excluded because this inspection did not establish a visible event trail.

Where the cameras stop, modelling begins

Towner and colleagues use Murrili to examine the unobserved descent after the luminous flight. Their calculation advances the body through atmospheric density and wind, with assumptions about mass, shape and aerodynamic drag. Those quantities affect the predicted landing region. Their comparison of different wind-model starting snapshots produces different fall lines. Even a steep, well-observed entry can leave substantial uncertainty below the last camera measurement. A plotted descent is consequently a model result, not additional footage of the meteorite falling through the lower atmosphere.

Recovery was a separate field operation

Curtin’s contemporary January 2016 account describes a three-day recovery effort involving aerial spotting, ground searchers and guidance from Arabana men Dean Stuart and Dave Strangways. Trevor Wright piloted the aerial search. Phil Bland dug the meteorite from a hole forty-two centimetres deep on New Year’s Eve. Rain had made the site harder to recognise and the lake surface difficult to cross. This account links the camera-based search prediction to a physical recovery, while preserving the local assistance that made access and searching possible.

A recovered rock tests the prediction

The later dark-flight study compares model predictions with Murrili’s recovered position and shape. It finds that shape assumptions can shift predicted positions more than mass or density choices in its tested scenarios. The authors explore possible orientations but cannot establish a unique descent orientation from this event. The practical success of recovery therefore coexists with unresolved aerodynamic questions. Read the predicted fall line, the recovered location and the camera observations as different kinds of evidence, each answering a different part of the journey.