Thanks very much for these guides, they are excellent. -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Canopus56 Sent: Saturday, April 17, 2010 11:08 PM To: Utah Astronomy List Serv Subject: [Utah-astronomy] Finding M101 in the UMa Galaxy Group M101 in UMa is one of the fainter Messier objects at 8.7v and an approx. 21 arcmin diameter. That gives M101 an mpsas (magnitudes per square arcsec) of 24.4, far less than the easier seen M51 also in UMa at 21.8 mpsas. I have never really seen M101 - which is famous as an example of a face-on grand spiral. I only have seen glimpses of its bright core - even from a good mag 5.5 ZLM location. M101 is best seen in its current spring orientation along with Realm of the Galaxies prime viewing. It is effectively "upside down" from my perspective. Although difficult to see, M101 can be easily found by following a line of brighter stars from Mizar - 81 UMa, 83 UMa, 84 UMa and 86 UMa: Finder Chart M101 http://www.slas.us/gallery2/main.php?g2_itemId=3236 This an celestial coordinate chart that is presented in a spring alt-az orientation for Salt Lake City. The pipe asterism shown on the chart is easily seen from even my urban light polluted site - while the galaxy is invisible. Depending on the degree of light pollution, a corner star in the bottom of the pipe - SAO28947 v8.7 - may not be visible in a finder or binoculars. Once the base of the pipe has been located, a short 1 deg slew should target M101. The bowl-of-the-pipe asterim can be found by several routes - via Mizar as discussed above - or via the M51 two star pointer at 24 CVn, or via a pointer defined by kappa Boo and iot Boo. See chart. With 5 deg binos or a 4 deg finder, begin by locating midway between Mizar and Alkaid (eta UMa, the end-of-dipper star) or between Alkaid and theta Boo. While M101 cannot be seen from an urban location, a locator star hop can easily be practiced during the week in preparation of a dark sky site weekend adventure. Clear Skies - Kurt P.S. - In reviewing the "Realm of the Galaxies" sequence, I have omitted Canes Venatici and its associated showcase galaxies, M94, M63, NGC5005 and NGC4449. In 3D, both the UMa Group and the Canes Venatici Galaxy Group lie next to and on the far side of the main Virgo Cluster. Virgo Supercluster Plot in galactic Y and galactic Z planes with UMa and CVn Groups emphasized http://www.slas.us/gallery2/main.php?g2_itemId=3239 Color coding - Red - Ursa Major Cloud and Ursa Major Southern Spur Green - Canes Venatici - Camelopardalis Cloud and Canes Venatici Spur Teal - Virgo-Libra Cloud Dark Blue and Back - Other Virgo Supercluster _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com