Apargon

Example

Tonight’s sky

Is the ISS flying over tonight, and when?

01 · The questionSomeone says the space station flies over tonight.When, and where do you look?

02 · OnceThe first time, type where you watch from.The app saves it in sky.json, next to itself.

03 · TonightEvery pass after dark, and which ones you can see: your sky dark, the station still in sunlight.Then the planets and the Moon.

04 · Look upFive minutes before a visible pass, a notification tells you where to look.

05 · OfflineOnce a day it fetches the station’s orbit from celestrak.org, and that’s all it sends out.Your location stays on your computer. Offline, it uses the last orbit.

Tonight’s sky

Tonight’s skyHome · 51.48° N, 0.01° W Change

Where do you watch from? Right-click a spot in any map app to copy its latitude and longitude.

Latitude, longitude

51.4779, -0.001551.48, -0.01

Name, if you like

HomeHome

Show my sky

ISS passesafter dark, above 10°

StartsRises → setsHighestLasts

Tonight

18:51W → ESE64°6 minVisible

20:24W → SE23°5 minVisible to 20:27

21:58WSW → S12°3 minIn Earth’s shadow

PlanetsDark 17:15 to 06:13

RisesSetsAfter darkHighest

Mercury08:1616:54Not up after dark

Venus06:2415:47Not up after dark

Mars23:1514:28From 23:5555° SSE

Jupiter23:5914:36From 00:4050° SSE

Saturn16:0104:18Until 03:4040° S

Moon

Waning gibbous · 92% lit↑ 17:25↓ 11:32

From celestrak.org: the ISS orbit fetched 28 Oct at 09:12. Your location stays on this computer.Offline: using the ISS orbit fetched 28 Oct at 09:12. Your location stays on this computer.

~/Sky/sky.json
{  "lat": 51.48,  "lon": -0.01,  "name": "Home"}

Tonight’s sky · nowThe ISS in 5 minLook W at 18:51. It climbs to 64°.

No internet

~/Sky/sky.json
{  "lat": 51.48,  "lon": -0.01,  "name": "Home",  "tle": [    "ISS (ZARYA)",    "1 25544U 98067A   26301.39127315  .00005312  00000+0  10412-3 0  9993",    "2 25544  51.6337   0.6152 0007021 318.9944  41.0476 15.49091877592408"  ],  "fetched": "2026-10-28T09:12:00.000Z"}

Try it.

Put the app in a folder with your files, and double-click it.

Your files. Nothing. The first time, it asks for your latitude and longitude and saves them in sky.json, with the ISS’s orbit, which it fetches from celestrak.org once a day.

It asks for three things. <meta name="papp-net" content="celestrak.org:443"><meta name="papp-write" content="./sky.json"><meta name="papp-use" content="notifications">

See the code for yourself

Or ask your AI for your own version. That’s the point.

More examples