SMART-1 Impact Observation at the Canada-France-Hawaii Telescope
Bibliographic record
Abstract
Introduction: Thanks to a well-planed ending of its mission, the SMART-1 spacecraft crashed on the near side of the Moon on the 3 of September 2006 at a site not illuminated by the Sun and visible from many large observatories in the Americas and the Pacific region. An observing campaign coordinated by the SMART-1 team triggered many attempts by both professional and amateur astronomers to observe the impact from the Earth. Bad weather in many observing sites and the difficulty to observe the Earthshine-lit crash site so close to the Sun-illuminated lunar surface led to only one successful observation at CanadaFrance-Hawaii Telescope and a possible detection of the impact flash by an amateur in New Mexico. The image of the impact flash, made available in near real-time by CFHT, brought visual closure to a very successful mission, and the detection of the impact plume on subsequent frames opened the possibility to study for the first time the dynamics of the ejecta from an impact on the lunar soil. Observing setup: The instrument available on the CFHT 3.6-m telescope at the time of impact was a brand new wide-field infrared camera, WIRCam. Each WIRCam image covers a 20’x20’ field, thanks to a mosaic of four very sensitive Hawaii-2 RG detectors. The 16 MPixels images are read in a few seconds. Image scale is 0.3”/pixel. With a 5-second gap between images and not knowing the exact time of impact, it was decided to set the exposure time at 10 seconds, giving a 2/3 probability of actually observing the impact. With the sunshine lit lunar surface close to the impact site and the relatively bright (for WIRCam) Earthshine lit impact area, the narrowest filter available in the camera was used: a molecular hydrogen emission filter H2 v=1-0 S(1) at 2130nm. Test images were made of the crash site the day preceding the impact, allowing a reconnaissance of the impact area and the landscape features to be used as reference for the impact observation. The impact flash: The impact did not happen between two images and was, luckily, recorded. The telescope was pointed so that the smallest portion of the mosaic would see the Sunshine lit area. The impact was therefore located very close to a corner of the mosaic. he corresponding image showing the whole detector on that corner is seen on Fig 1. Scripts processing the images in real time allowed a release of the flash image a short time after it was observed. The data actually consist in a long sequence of 10s images covering nearly an hour (20mn before the impact and 40mn after). As the Earthshine lit Moon has a very low contrast, features are not easily seen. For this work, the Virtual Moon Atlas [1] was very useful. The impact was localized on the slopes of a mountain seen on the SMART-1 image of the impact zone (Fig 3). Fig 1 The 2Kx2K detector used for the impact observation. The sunshine lit Moon is at the extreme upper right of the detector (saturated – hence black). The Earthshine lit Moon is seen with the starry sky in the background. Various ugly reflexions from the bright Moon are seen in many places... The impact flash is the bright spot at the top of the image, close to the terminator.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".