NASA publishes refinements every couple of days as the orbit is updated. A 12-hour cache duration in SleekRank keeps the city pages within one refinement cycle of upstream. For more time-sensitive use, drop to 6 hours and let the cache layer absorb the extra requests. The base page does not change; only the row in the feed changes.

Yes, with a secondary data source. Generate per-city passes from any orbit propagation library using TLE data from CelesTrak, write the output into the same JSON shape as the Spot the Station export, and merge the two before SleekRank reads them. The base page renders both kinds of rows identically.

Each city row is independent because the predicted times vary by minutes per longitude degree, and the max elevation depends on latitude. SleekRank does not deduplicate; the data layer does. If two suburbs share a metro and you want a single page, give them the same slug or merge them in the export.

Yes. Add additional rows per satellite per city, like /iss-passes/chicago/ for the ISS and /tiangong-passes/chicago/ for Tiangong. Run two page groups against the same shape of data, or add a satellite column and split the URL pattern by category. The base page works either way.

If the upcoming-passes list for a city is empty because the next pass is more than ten days out, a selector mapping checks the count and renders a 'next visible pass after [date]' message instead. The base page handles both states without a separate template.

Yes. Each page emits a JSON-LD Event block for the next visible pass with startDate, endDate, location coordinates, and a name like 'ISS visible pass over Chicago on March 15'. The structured data makes the next pass eligible for event-style search results and feeds rich-result preview cards.

Server-side rendering uses the city's local timezone because that's what the search intent demands. A lightweight Alpine widget on the page can offer a visitor-tz toggle if the audience is international, but the canonical render stays city-local so search engines and link previews see the right times.

Equatorial cities see frequent passes; far-northern and far-southern cities see seasonal ones. The base page handles both because the list mapping renders whatever the feed says. For cities where passes drop to zero for weeks, the page reads as 'no visible passes scheduled' and reactivates automatically when the orbit comes back into range.