the galaxy Messier 87, also detected by Chandra. Like the former, no human will hear the note. The tone is variable, and even lower than those generated by NGC 1275, from 56 octaves below middle C on minor eruptions, to as low as 59 octaves below middle C on major eruptions. Image gallery See also References External links Fabian, A.C., et al. A deep Chandra observation of the Perseus cluster: shocks and ripples. Monthly Notices of the Royal Astronomical Society. Vol. 344 (2003): L43 (arXiv:astro-ph/0306036v2). The galaxy cluster Abell 426 (Perseus). A catalogue of 660 galaxy positions, isophotal magnitudes and morphological types, Brunzendorf, J.; Meusinger, H., Astronomy and Astrophysics Supplement, v.139, p. 141–161, 1999. The galaxy cluster Abell 426 (Perseus). A deep image of Abell 426 Space.com article about "Sound of a Black Hole." in the Perseus cluster http://aida.astroinfo.org/ Perseus A: Mysterious X-ray Signal Intrigues Astronomers Galaxy clusters Perseus (constellation) Perseus-Pisces Supercluster 426 Abell richness class 2