Observer's guide
About NGC 4258
NGC 4258 (M106) is catalogued as a spiral galaxy in Canes Venatici. Its J2000 position is RA 12:18:57.50, Dec +47:18:14.3, corresponding to 184.7401 degrees RA and 47.3037 degrees Dec. The local catalogue places it about 25,000,000 light-years away. Its referenced angular extent is approximately 17.78 by 6.92 arcminutes.
Observing tips
This is rated as a hard target at magnitude 8.4. It is associated with spring observing, with midnight placement typically strongest around March. From 52 degrees north its theoretical meridian altitude is about 85.3 degrees; local horizons and the live altitude chart determine the practical window.
A small telescope under reasonably dark skies is a good starting point; use the live altitude chart to choose its highest point.
What to expect
The SIMBAD classification for the matched source is Sy2. SIMBAD records the morphology as SAB. A published radial velocity value is 506.8 km/s. The SIMBAD record currently connects it to 2540 bibliographic references.
At roughly 17.8 arcminutes across, it benefits from a narrower field and adequate image scale. Use the listed 17.78 by 6.92 arcminute extent to check framing, and treat catalogue magnitude as integrated brightness rather than a direct measure of visual contrast.