/dso

/dso <name> [location] [remember] [night]

Looks up a deep-sky object — a galaxy, nebula, or star cluster — from the Messier catalog (110 objects, Charles Messier’s 18th-century “greatest hits” list, still the standard amateur-astronomy starting point) or the much larger NGC/IC catalogs (New General Catalogue / Index Catalogue, tens of thousands of objects). With a location available, also shows tonight’s full altitude-over-time visibility chart in the same response, automatically — no separate step needed.

Usage: /dso name: M31, /dso name: NGC 6960, /dso name: Andromeda Galaxy, and /dso name: Veil Nebula all work. Messier objects are checked first (and include a hand-picked “notable” fact); NGC/IC results show the core data (type, size, brightness, coordinates) without that extra commentary, since that’s not practical to write for tens of thousands of objects.

Add a location (or have a saved default) to also see whether it’s currently above your horizon, plus tonight’s rise, set, and transit (meridian-crossing) times, peak altitude, and a full altitude-over-time chart with dark-sky periods shaded and a dashed line at 30° marking a common “good imaging altitude” threshold. remember: True saves a typed location as your new default. With no location at all, the catalog info above still works on its own — you just won’t get the chart or a current- visibility line. Shows a thumbnail image from Wikipedia when one’s available for that specific object.

With a location it also adds an Imaging Guide: max imaging time (target above 10° during astronomical darkness), the Moon’s illumination and distance from the target at local midnight, whether the Moon is far enough away for Ha/SII, OIII and LRGB imaging, and a 7-night outlook. The Moon thresholds are an estimate modelled on Telescopius, not a hard rule, and local midnight use your location’s real time zone.

Planning ahead: date picks the evening to plan — /dso name: M42 date: 2026-12-05, date: 12/05 or date: tomorrow. It drives the chart, the rise/set times and the Imaging Guide. Default is tonight.

Note: the NGC/IC catalog requires a one-time setup step by the bot’s operator (scripts/fetch_ngc_catalog.py) — without it, only the Messier catalog is searchable.

Coordinates button: the 📋 button replies (only you see it) with the target’s J2000 and JNow coordinates, in hours/minutes/seconds and decimals, ready to copy into mount or planetarium software that wants JNow. JNow is for today, by precession alone.

Parameters

Name	Required	Description
name	Yes	Catalog number (M31, NGC 6960, IC 434) or common name (Andromeda Galaxy, Veil Nebula)
location	No	Optional: city, decimal or DMS coordinates, for visibility, a chart and an imaging guide
remember	No	Also save this as your new default location (otherwise this is a one-off lookup)
night	No	Evening to plan: YYYY-MM-DD, MM/DD or tomorrow. Default: tonight