Radar observations of the 2011 October Draconid outburst
Bibliographic record
Abstract
A strong outburst of the October Draconid meteor shower was predicted for 2011 October 8. Here we present the observations obtained by the Canadian Meteor Orbit Radar (CMOR) during the 2011 outburst. CMOR recorded 61 multistation Draconid echoes and 179 single-station overdense Draconid echoes (covering the magnitude range of +3 ≤ MV ≤ +7) between 16 and 20 h ut on 2011 October 8. The mean radiant for the outburst was determined to be αg = 261| $_{.}^{\circ}$|9 ± 0| $_{.}^{\circ}$|3, δg = +55| $_{.}^{\circ}$|3 ± 0| $_{.}^{\circ}$|3 (J2000) from observations of the underdense multistation echoes. This radiant location agrees with model predictions to ∼1°. The determined geocentric velocity was found to be ∼10–15 per cent lower than the model value (17.0–19.1 km s−1 versus 20.4 km s−1), a discrepancy we attribute to undercorrection for atmospheric deceleration of low-density Draconid meteoroids as well as to poor radar radiant geometry during the outburst peak. The mass index at the time of the outburst was determined to be ∼1.75 using the amplitude distribution of underdense echoes, in general agreement with the value of ∼1.72 found using the diffusion-limited durations of overdense Draconid echoes. The relative flux derived from overdense echo counts showed a similar variation to the meteor rate derived from visual observations. We were unable to measure the peak flux due to the high elevation of the radiant (and hence low elevation of specular Draconid echoes). Using the observed speed and electron line density measured by CMOR for all underdense Draconid echoes as a function of height as a constraint, we have applied the ablation model developed by Campbell-Brown & Koschny. From these model comparisons, we find that Draconid meteoroids at radar sizes are consistent with a fixed grain number ngrain = 100 and a variable grain mass mgrain between 2 × 10−8 and 5 × 10−7 kg, with bulk and grain density of 300 and 3000 kg m−3, respectively. One particular Draconid underdense echo displayed well-defined Fresnel amplitude oscillations at four stations. The internal synchronization allowing us to measure absolute length as a function of time by combining the absolute timing offsets between stations. This event showed clear deceleration and modelling suggests that the number of grains for this meteoroid was of the order of 1000 with grain masses between 10−10 and 10−9 kg, and a total mass of 2 × 10−6 kg.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".