Every object in the catalog starts a session with a perfect score of 100, and StarYard subtracts points for anything that makes it a harder target with your specific telescope, camera, and sky on that specific night.

How Deep-Sky Objects are Scored

For deep-sky objects, the biggest factors are:

• How the object's magnitude compares to what your aperture can realistically capture in a long exposure
• How much your local sky brightness (Bortle class) will wash out the target, an effect that's reduced if the object is narrowband-friendly and you own a narrowband filter
• Whether the object fits well in your camera's field of view (too large and it gets cropped, too small and it barely fills the frame)
• Whether it resolves into enough pixels to show real structure rather than an indistinct blob, given your focal length and pixel size
• How long the object stays above your usable altitude and horizon that night (a short window is penalized on a sliding scale, not a hard cutoff)
• How much the Moon will interfere, weighted by both how much of the object's visible window overlaps with the Moon being up and how illuminated the Moon is (narrowband imaging is penalized less here too)

How Planets are Scored

Planets are scored differently, since they're almost always bright enough to see regardless of sky darkness or moonlight. For them, the dominant factor is simply how large the planet's disc will appear in pixels through your equipment, since a tiny disc yields no visible detail no matter how bright the planet is.

Summarizing Scoring Factors

Each of these factors contributes a point deduction (not a simple average), and the object's final 0-100 score maps to a label: Excellent, Good, Fair, or Poor. Alongside the score, StarYard provides the specific reasons behind it ("faint target," "short visibility window," "Moon interference", etc.) so you can see why something ranked where it did, not just the number. Objects that never clear the horizon or minimum altitude at all during the night are excluded from the recommendation list entirely rather than scored. The list itself is then sorted highest-score-first, so the top of the results screen represents the best match between your gear, your sky conditions, and that night's astronomy.

The object score does NOT take into account weather conditions. These are provided seperately.