IFUM: integral field units for Magellan
Bibliographic record
Abstract
IFUM (Integral Field Units for Magellan) consists of three IFUs at the Nasmyth-East focus of the Magellan/Clay telescope. Each IFU consists of a Barlow lens, a lenslet array, a set of fiber assemblies that feed a pair of fiber shoes that allow the fibers to be used with the twin spectrographs of M2FS (the ‘Michigan/Magellan Fiber System’). The IFUs are optimized for excellent seeing conditions (the ‘HR’ IFU with 864 fibers with 75µm diameter cores), standard seeing conditions (‘STD’, 552 fibers, 150µm) and extended (low surface brightness) targets (‘LSB’, 360 fibers, 260µm). The Barlow lenses magnify the field at the lenslet arrays which deliver to each fiber images the telescope entrance pupil (the primary mirror) at f/3.5—as defined by the marginal rays of the pupil image—that becomes an f/3.3 output beam at the spectrographs. The fiber assemblies consist of ‘sky-end’ fiber mounts that are aligned with the lenslet arrays to high precision and ‘spectrograph-end’ fiber mounts that maintain the fibers at the focal surfaces of the spectrographs within the fiber shoes. The fibers can be aligned within the shoes with slits that deliver spectral resolutions ranging from ℛ = 1200 to 40000. Movable focal-plane masks on each IFU enable spectroscopy of faint sources near much brighter point sources (e.g. AGN or young stellar objects). IFUM can be used with a deployable ADC on the Magellan/Clay guider; a separate deployable mirror on the guider allows onboard calibration light sources to illuminate any of the IFUM IFUs. Initial commissioning data are presented.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.146 | 0.082 |
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".