Layer 7 — Delivery and rendering

One set of chart data can become a wheel, a table, a moving graph or a printed report. Each view makes some relationships easier to see. Choosing a view is therefore part of explaining the chart, even though it does not change the sky used to calculate it.

Ephemeris engine

An ephemeris engine does the numerical work of calculating positions. An adapter translates its interface into an application’s shared contract. The engine produces the astronomical result; the adapter makes that result usable alongside other providers.

To reproduce a position, an engine name alone is not enough. Its version, data files, flags, time model and observer context can all affect the answer. Licensing and availability should be checked with the provider.

Chart wheel

A chart wheel puts the longitude circle on the page. A sign ring shows the zodiac sectors, a house ring shows local divisions, and glyphs, or compact symbols, identify bodies and signs. Lines through the centre connect selected aspects.

Rotating the drawing can put the Ascendant in a convenient position without changing any stored longitude. Wheel style describes choices such as ring order, glyph set and aspect-line treatment, rather than a new chart calculation.

Wheel editor

A wheel editor changes presentation: colours, line weights, glyphs, ring layout and numbering. If you make an aspect line thicker, its angle stays the same. If you change the house system, the calculated house spans can change.

That distinction helps a reader understand a moving symbol. It may have moved because the drawing changed, or because a calculation setting changed. Clear controls keep those causes understandable.

Dynamic lists

A dynamic list is a table generated from a chart or time interval. For example, an aspect list can collect the times a pair becomes exact during a month. Another list might show daily samples or the times a pair enters its permitted orb.

All three are useful, but they answer different questions. Column labels and event definitions let a reader tell an exact crossing from a sampled state. The list is a presentation of events or positions, rather than a timing technique itself.

Graphical ephemeris

Put time on one axis and longitude on the other, then trace a body’s position. The result is a graphical ephemeris. A curve shows movement that would be difficult to notice by reading a column of daily numbers.

Retrograde motion reverses the curve’s slope. At a station the slope reaches zero. An ingress, a crossing into another sign, appears when the curve passes a sign boundary. Some graphs fold longitudes into 90° or another modulus to bring selected angular relationships together.

A plotted jump from 359° to 0° is angle wrapping. The body crossed the measuring circle’s zero; it did not leap backward across the sky.

Astro sheets

Astro sheets is a product label for readable or printable tables: planetary positions, house cusps, aspects and midpoint lists. A midpoint list records the points halfway between selected pairs of longitudes.

A sheet should still make sense away from its wheel. Units, zodiac, house system and midpoint conventions give the numbers enough context to be read or compared later.

Animator / chart stepper

A chart stepper advances the calculation instant by a selected interval. An animator repeats those steps so a reader can watch positions and relationships develop. A slowly moving transit becomes easier to follow when time can be paused or advanced.

A step of one civil day is not always 24 elapsed hours across a daylight-saving transition. The displayed timezone and step unit explain what “next day” means in the control.

REST / JSON API

An API is an interface another program can call. A chart request can carry an instant, place and calculation settings, then receive positions, houses or aspects in return. JSON is a text format for representing those values; REST describes a style of HTTP resource interactions.

MCP, Model Context Protocol, can expose calculations as tools for compatible clients. That adds another way to request a calculation. The scientific model and astrological rules still come from the service behind the interface.

Render formats

Rendering turns chart data into a visible artifact. The right format depends on how that artifact will be used:

Enlarge a small PNG and it can blur; enlarge an SVG and its vector lines stay sharp. Both can contain exactly the same calculated positions. Image resolution and astronomical accuracy are different properties.

Cloud sync

Cloud sync makes saved chart data available across devices or from remote storage. Saving the birth inputs and settings lets a chart be calculated again. Preserving an exact historical output also calls for its result and provenance, the record of how it was produced.

A calculation service can be stateless: it answers a request without keeping a user’s chart collection. Accounts, durable storage and synchronisation are then responsibilities of the surrounding application. The software vocabulary follows that boundary in more detail.

Guide index · A–Z lookup · Sources · Next: Binder and architecture terms