My Keenan image exposures consist of 20 hours of LUM 1×1 and 3 hours each RGB 2×2 using the 14.5-inch RCOS at Chiefland Astronomy Village with an Apogee U16M CCD Camera. The wide angle image shows the myriad of distant galaxies in that Ursa Major region of the sky!! I made an attached comparison mosaic, as Adam Block did years ago, of my image vs. the galactic merger movie stopped at 1:40 min. The similarity is eerie and suggests validation of the computer simulation program predicting the stages of formation of Milkomeda in that there is an existing form in nature (Keenan) that supports it. An attached inverted luminance shows long tidal extensions. The close-up is look at two interacting galaxies just 4 arcminutes apart! One of my goals was to see how close I could come imaging from Chiefland with a 14.5-inch scope to the depth and definition of the 24-inch and 32-inch telescope images from lofty Mt. Lemmon. Fun challenge!
P.S. – The ID of the Keenan galaxies is incorrect in both the July 2, 2010 and July 31, 2008 APODs (see write-up below). The distance is also off by a factor of 10!
P.S.2 – Perhaps the term “Milkomeda” was coined by Adam Block??https://www.youtube.com/watch?v=jbXgQaCobLc – Computer Simulation of collision of Milky Way and Andromeda Galaxies 3 billion years in the future (“Milkomeda”); check out image at 1:40 and compare to Keenan’s System!
http://apod.nasa.gov/apod/ap100702.html – July 2, 2010 APOD – 24-inch RCOS atop Mt. Lemmon, Arizona
http://www.caelumobservatory.com/gallery/n5216.shtml – 32-inch RCOS atop Mt. Lemmon
http://apod.nasa.gov/apod/ap080731.html – 2008 Keenan APOD
NGC 5216 (= PGC 47598, and with NGC 5218 = Keenan’s System = Arp 104)
Discovered (Mar 19, 1790) by William Herschel
A 13th-magnitude elliptical galaxy (type E2 pec) in Ursa Major (RA 13 32 07.1, Dec +62 42 03)
A gravitationally interacting pair with NGC 5218, referred to as Keenan’s System, or Arp 104. (The pair is used in the Arp Atlas as an example of an elliptical galaxy connected to a spiral galaxy.) A Seyfert galaxy (type Sy1). Based on a recessional velocity of 2940 km/sec, NGC 5216 is about 135 million light years away, in fair agreement with redshift-independent distance estimates of 155 to 185 million light years. Whatever the actual distance, the galaxy must be at essentially the same distance as its companion, NGC 5218, so I have adopted a common distance of 160 million light years for comparison purposes. Given that and its apparent size of 2.6 by 1.9 arcmin, NGC 5216 is about 120 thousand light years across. The overall extent of Keenan’s system, including the trails of gas extending between and beyond the pair, is about 250 thousand light years. (This pair was featured as the Astronomy Picture of the Day for July 2, 2010. Unfortunately, the accompanying description of the system contains a factor of ten error in distances and dimensions, and reverses the NGC identifications. This is an example of an all-too-common propagation of incorrect data across the Internet; but LEDA and NED make it clear that the system is much more distant than usually stated, and even the NOAO site, although also giving incorrect dimensions and reversing the NGC identifications, correctly states that it is well over 100 million light years away. The APOD caption also incorrectly states that Keenan discovered the system. William Herschel was the first to record the nebulae; Keenan discovered the bridge of stellar material connecting the pair.) The July 31, 2008 APOD showing Keenan also incorrectly identifies the galaxies and distance.