Why would an astro sketcher need a block of sandpaper?
I pondered that very question the first time I stumbled across a small wooden paddle with strips of sandpaper stapled to it while browsing for art supplies. As it turns out, it’s so handy that I use it during most observing sessions. I’ve included sketches of NGC 4747 and NGC 4725, galaxies in the constellation Coma Berenices, to explain how.
You can locate this duo some 5½° northwest of Beta (β) Comae Berenices. The smaller of the two, NGC 4747, appears as the 159th entry in Halton Arp’s Atlas of Peculiar Galaxies. It sports tidal tails from its interaction with NGC 4725, which lies 24' farther to the southwest. The galaxy itself measures 3.5' by 1.2' and glows at magnitude 12.3. Through a 10-inch scope, it appears as a faint oblong halo with a brighter center. And you’ll find a wide double star (7th and 10th magnitudes) 7' to its south.
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