TIDEGLASS OBSERVATORY
Night study · A spectral deduction game

Four lights. One imperfect lens.

Read what the stars
leave behind.

Four unknown stars share a drifting spectrometer. Spend eight exposures to identify their distinct spectral classes. Calibrate the lens, or let the stars reveal its error.

Exposures remaining
Classifications locked
Possible skies
Score

The shared lens

Uncalibrated

Every reading = true band intensity + the same hidden drift. Drift is an integer from −2 to +2. There is no measurement noise.

Drift consistent with your evidence

Calibration reveals the exact drift. Comparing stars can reveal it for free. Each class occurs at most once among these four stars.

The six possible spectral fingerprints
ClassRedGreenBlue
Scoring and the end of the night
  • 100 points for each correct classification.
  • 25 more points for a correct classification if only one class was consistent with the evidence when you locked it. The cards tell you when this is certain.
  • 6 points per unused exposure, awarded at the end. Maximum theoretical score: 548.
  • You may observe or calibrate up to eight times total. Each band of each star can be observed once; calibration can be used once.
  • A locked star cannot be observed or changed. Its verdict is revealed only when all four stars are locked. Locking a guess adds no evidence.
  • The night ends after four classification locks. Out of exposures? Use the evidence you have and lock the remaining stars. There is no timer.
  • New nights are generated at runtime. All four classes are different. Every night can be solved with eight exposures by observing red and green on all four stars; smarter shared deductions can save exposures.

Observer’s desk

Practice night

observe A red · calibrate · classify A ember
state, moves, and help are always free. A batch checks each move and stops at its first error.

The lens has drifted. Choose a star and a band, or calibrate first.

Complete public text state
Every legal command right now





A note on evidence
  • The candidate lists compare all your measurements with every distinct four-class sky and every possible drift.
  • One star’s measurement may narrow another star’s possibilities. Look at all four cards after each exposure.
  • “Certain” means the evidence forces one class, even if other details of the sky remain unresolved.
  • You can gamble on any class, including one contradicted by the evidence. Locking is final; no correctness feedback arrives early.
  • Only revealed observations and public rules appear in the text state. To play fairly, reason from them.
  • Your night stays available while this page is open. Browser storage is used only when available; reloading a sandboxed page may start a new night.
Field notebook
0 moves