The bright, textured band of the Milky Way that fills astrophotographs is the galactic core, in the direction of Sagittarius. It is only above the horizon at night for part of the year, it needs a dark sky, and it moves — so a good core photograph is a scheduling problem before it is a camera problem. Lightpath handles the schedule; this guide covers the camera.
From mid-northern latitudes the core season runs roughly February to October. Early in the season it rises in the south-east shortly before dawn; by June and July it is up for most of the night and highest around midnight; by September and October it sets in the south-west soon after dark. The rest of the year the sun sits between Earth and the galactic centre and the core is only up in daylight.
On the Today tab the lighter band low on the Light timeline marks when the core is above 10° altitude, and the Coming up list gives Milky Way core rises with the direction to shoot. On the Planner, the CORE line on the map shows the azimuth for the time on the slider; the card below shows its altitude. The Shot Score's Light bar rewards a dark sky with the core above 10°.
Sun. You need astronomical twilight to have ended: sun below −18°. The timeline's Full dark band and the Full dark — best for stars event mark this.
Moon. A moon above the horizon at more than a thin crescent will wash out the core. The Moon bar in the Shot Score drops sharply at night as the illuminated fraction grows. Plan around the new moon; the New moon label on the Planner tells you where you are in the cycle.
Light pollution. Lightpath does not model this. Use a dark-sky map to choose the spot; the Bortle scale (1 = pristine, 9 = inner city) is the standard vocabulary. Under Bortle 4 or better the core is obvious to the eye; under Bortle 6 it is a photographic exercise only.
Stars move. Leave the shutter open too long and they smear into short trails. The old "500 rule" (500 ÷ focal length = seconds) was designed for film and 6-megapixel sensors and gives trails on any modern camera. Lightpath uses the NPF rule instead, published by Frédéric Michaud of the Société Astronomique du Havre, which accounts for aperture (N), focal length (F) and the sensor's pixel pitch (P, in micrometres). The app implements the simplified form of the rule for stars near the celestial equator:
t = (16.856 × N + 0.0997 × F + 13.713 × P) / F seconds
In Tools › Stars, pick your sensor and enter focal length and aperture. The result is the longest shutter that keeps stars as points at the centre of the frame. A typical full-frame 20 mm f/2.8 lands around 12–13 seconds — not the 25 the 500 rule would suggest.
The Stars tool also shows the arc length stars will trace for a chosen number of minutes, which is what you want if you are deliberately making star trails.
Lightpath's night recipes start at 20 mm, f/2.8, ISO 3200 with the NPF shutter. That is a good baseline for a Bortle 3–4 sky. Adjust ISO, not shutter: raise it under darker skies, lower it if the core is blowing out. Focus manually on a bright star using magnified live view; autofocus will hunt.
Showers are a bonus during core season. Tools › Sky events lists the upcoming major ones. The two most reliable are the Perseids (peak around 12–13 August) and the Geminids (13–14 December); check the moon phase for the peak night, since a bright moon halves the visible rate.
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