Photomnemonic Tablet

First Appearance and Context

A photomnemonic tablet is a dark, glassy disk used on the rooftop Starhenge above the Mynster to capture and replay observations. In instructional use, a tablet shows layered exposures of Saunt Tancred's Nebula that can be scrubbed back to the supernova peak.

Roles/Actions and Affiliations

• Time‑series capture: Tablets can be left installed to accumulate nightly exposures over extended spans and then replay them as an ordered stack. When used with Clesthyra's Eye, they record the whole sky; at customary settings a single tablet can continue for months before filling.
• Integration with instruments: The fixed all‑sky lens includes a tablet slot sized for this form factor, and the larger telescopes direct gathered light into a tablet for recording.
• Tolerated praxis: Tablets embed a syntactic device; their use is permitted within the Discipline as a grandfathered practice maintained alongside clock‑coupled systems by the Ita.
• Sensitive data source: In one documented case, a senior avout, Fraa Orolo, restricted access to tablets containing the observational “givens” behind an orbital‑mechanics effort, shielding students from potential consequences.
• Custody during restrictions: Following a rooftop closure and the aut of Anathem, a tablet left in the M & M was confiscated by hierarch staff, while another removed from Clesthyra's Eye was quietly secured by avout collaborators for later review.

Relationships

• Instruments and sites: Closely associated with the starhenge instrumentation and all‑sky lens; used by avout cosmographers for study and demonstration.
• Exemplar dataset: Long‑running records tied to Saunt Tancred's Nebula are associated with Saunt Tancred.

Descriptions/Characteristics

• Form factor and handling: A flat, dark, glassy disk about the size of two hands across and several fingers thick; often kept blanked and wrapped in a dust jacket until use.
• Operation: Activating its “remembrance” function begins recording. Without optical elements, light falling on a bare tablet cannot form a usable image; instrument optics supply the definition. When a tablet is inserted into the slot beneath the all‑sky lens and the dust cover is closed, it records continuously until it fills.
• Playback and controls: The display is self‑illuminated, allowing study in dark rooms. Controls include play/pause, fast‑forward, frame freeze, pan, and zoom; users can rapidly scan day‑by‑day frames and trim the beginning or end of a record to remove unwanted segments.
• Time integration and image geometry: A tablet can integrate all light over a configured span into a single still image, revealing faint structures. Under the all‑sky lens, such integrations show concentric star arcs centered on the pole, while moving lights trace dotted or bright curves; near‑polar objects register as nearly straight tracks that recur at regular angular separations.
• All‑sky projection specifics: When recording under the all‑sky lens, images have a fisheye geometry: the horizon forms the rim and the sky compresses toward the center; nearby subjects appearing at the rim are strongly magnified.

Current Status/Location

In active use on the rooftop observatory, with instructional examples retained in a heated workspace and other units periodically installed under the all‑sky lens for long‑run capture. During the recent aut, at least one unit was seized and another was hidden pending discreet examination in a dark room beneath Shuf’s Dowment.