Observer's guide
About NGC 4548
NGC 4548 (M91) is catalogued as a spiral galaxy in Coma Berenices. Its J2000 position is RA 12:35:26.45, Dec +14:29:46.8, corresponding to 188.8602 degrees RA and 14.4963 degrees Dec. The local catalogue places it about 60,000,000 light-years away. Its referenced angular extent is approximately 5.25 by 4.32 arcminutes.
Observing tips
This is rated as a very hard target at magnitude 10.2. It is associated with spring observing, with midnight placement typically strongest around March. From 52 degrees north its theoretical meridian altitude is about 52.5 degrees; local horizons and the live altitude chart determine the practical window.
Because it is faint, use a larger aperture where possible, avoid bright Moon conditions, and use averted vision.
What to expect
The SIMBAD classification for the matched source is LIN. SIMBAD records the morphology as SB_a. A published radial velocity value is 489 km/s. The SIMBAD record currently connects it to 643 bibliographic references.
At roughly 5.3 arcminutes across, it benefits from a narrower field and adequate image scale. Use the listed 5.25 by 4.32 arcminute extent to check framing, and treat catalogue magnitude as integrated brightness rather than a direct measure of visual contrast.