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NightSeam Web
night-planning, computed in your browser
Observing setup
Time
Weather · active site
Weather loads when you click the chip above, or at startup when auto-load is on. Once loaded, changing the site fetches a new forecast.
Options
When on, the app fetches weather for the active site every time it opens, so the chip is already filled.
Data
Display
Takes that much space away on each side of the content. 0 lets it fill the window, higher values center a narrower column.
Scrub across the whole 24 h day. Off (default) keeps the scrub on the night itself — sunset to sunrise.
Advanced
Standard mode shows 200 well-known targets; advanced adds the full OpenNGC catalog — NGC/IC plus its addendum and a 16-object supplement OpenNGC cannot carry (12,176 objects to magnitude 20). Switching updates the catalog in place; calculating visibility for the full catalog can take a moment.
Plan and display the night in this zone (only in advanced mode). Empty = the active site's zone, or this browser's zone. DST is applied per date.
Ranks targets down while the Moon is up; objects far from the Moon and clusters survive moonlight best.
1 = pristine dark sky, 9 = city centre. Darker skies lower the default minimum altitude and weaken moonlight penalties.
These describe your filters and mark matching recommendations. With Moon-aware ranking on, Hα/OIII also change Tonight's Moon penalty; OIII takes priority over Hα, otherwise broadband is assumed. They do not change visibility or usable times.
About
NightSeam … — deep-sky night planning.
MIT licensed. Astronomy calculations run on this device; planning data is saved in this browser.
Optional weather and external object photos use online services.
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