Author Topic: Springtime galaxies ...finally!  (Read 107 times)


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Springtime galaxies ...finally!
« on: April 03, 2017, 06:35:12 PM »
Last Tuesday (March 28th), with the new moon observing window starting to close, Mark McCarthy and I observed at Kevin Ritschel's ranch in the hills southeast of Hollister (Willow Springs).  The drive south from Berkeley in the afternoon was pretty brutal due to accidents and slowdowns and the usual 2 ½ drive took me an extra hour.  Still, I arrived about an hour before sunset and had plenty of time to set up my 24-inch and eat dinner while it was getting dark.  Mark arrived about a half hour after me and set up his 20-inch before I was finished.

About a half hour after sunset I started scanning in the west looking for Mercury but instead noticed an extremely thin arc, nearly lost in some low clouds and haze along the western horizon -- it was the crescent moon just 25 hours old!  Quite an exquisitely thin sight and totally unexpected.  About 15 minutes later I found Mercury, which was surprisingly bright and high -- both of us were initially unsure it was Mercury as it was so (relatively) high in the west.  But a quick look in Mark's scope (just a non stellar "blob") confirmed it was Mercury.  Turns out it was close to its maximum elongation (about 10° when we viewed it).

By 9:00 it was fully dark, but we could see some illuminated clouds along the western horizon and northern horizons.  Mark measured an SQM reading of only 21.2 or so (subpar for this site), but I believe it hit 21.5 or 21.6 sometime after midnight.  Early on we took a peek at comet 41P/Tuttle-Giacobini-Kresak near the Ursa Major/Draco border in Mark's scope.  This relatively bright and large comet seemed around 8th magnitude and contained a very prominent nucleus.  I also took a quick look at the planetaries NGC 2438 in M46 (Puppis) as well as NGC 2818A in the cluster NGC 2818 (Pyxis).  Neither of these planetaries are physically associated with the associated cluster.

I worked on three different programs in the evening -- each for a couple of hours.  First up was a number of IC galaxies in Gemini, Cancer, Canis Minor and Hydra.   The middle part of the evening was a survey of the central region of Hydra I galaxy cluster, which includes NGCs 3285, 3305, 3307, 3308, 3309, 3311, 3312, 3314, 3315 and 3316.  I took notes on 19 galaxies for a planned article in Sky & Tel next spring.  The cluster is a near twin of the downtown section of the Virgo cluster -- just 3 times as distant!  Late at night I focussed on a number of new (for me) Arp galaxies.  All in all, about 50 objects were viewed over 7 ½ hours.

One interesting galaxy was NGC 3067 in Leo, about 70 million l.y. distant.  The galaxy itself had lots of subtle structure -- logged as fairly bright, moderately large, elongated 5:2 WNW-ESE, mottled elongated central section with a sharp light cut-off (dust lane) on the northern flank.  The eastern end of the galaxy has a lower surface brightness, probably due to dust.  A very faint 16th magnitude star was easily visible 2' north.

This unassuming star is actually a super-luminous quasar (3C 232) at a distance of 5 billion light years and involved in one of Halton Arp's controversies.  A neutral Hydrogen "bridge" appears to connect the quasar and NGC 3067.  Arp proposed the QSR was ejected from NGC 3067, a theory which was rejected by mainstream astronomers.