Monthly Summary # 8: October/November 2013

It's now been one year of observing with the 12".  When I first set out to find all the NGC objects I could from my location, I thought it would be a daunting and difficult task.  I had no idea.  I figured that pointing a 12" Dob into the overhead sky would reveal anything and everything I wished to see.  It did, but what a task!  I expected (and got) trouble low on the horizon (see my previous post), but did not expect that much difficulty with overhead skies.  Finding some of these little faint objects from the NGC list has been really, really hard!  However, the experience I have gained in the past year has been impressive.  Knowing the limitations of one's scope (and eyes) is so important to observing.  It has been a lot of fun finding my limitations.

The good news is that I have seen every NGC and IC object in Lyra and Cygnus, and I am nearly done with Cassiopeia!  Last lunar cycle did not produce a bonanza of clear nights.  There were three that worked for us.  My biggest conquest (well, one of them) was locating the final unseen NGC galaxy in Lyra.  I saw it 45 minutes after sunset in one of the clearest skies I have ever experienced.  What makes eg 6686 so hard to see is its faintness (obviously) and its proximity to a bright star (mag 7.5, which looks like a streetlight in a 12").  I tried a number of times this summer.  However, the sky on this night was as perfect as it gets, and "bingo," there it was, in all its faint fuzziness.

Other impressive accomplishments include locating (just barely) eg 45 in Cetus, and enjoying my best view ever of pn 246, not far away.  The three sessions saw us observe for 11.5 hours.  I snagged 21 new NGC objects and one IC, plus 9 open clusters from other catalogues.  I give the facts below.

LYRA

eg 6686:  Mag. 14.45.  Very faint and elusive, but visible at 125x and 150x.  Small and round.  This completes my work in Lyra!!

CASSIOPEIA

gn 896:  These two nebula appear together, separated by a small black lane.  896 is quite good with a filter, and is the brighter of the two.
gn I 1795:  Appearing with 896 at low and medium powers, it is involved with a mag. 9 star.  Both easy objects with the ultrablock filter on a very fine night.
eg 1343:  Mag. 13.5.  Located at 125x, and observed at 150x and 200x.  Faint overall, but showing a brighter middle, and noticeably elongated.  2 faint stars lie immediately north.

CETUS

eg 45:  Mag. 12.5.  One of the biggest challenges in Cetus for northern observers is this large, very low surface brightness galaxy.  After many tries, I saw it on this one superb night.  6.9 mag. and 9.9 mag stars make this even harder to see.  Expect faint patchiness, in at least two locations.  Located at -23 degrees.  Good luck.
eg 113:  Mag. 13.3.  Oval and faint, a brighter center was noted at 200x.
eg 114:  Mag. 12.9.  Paired with 118, this was smaller but somewhat brighter.
eg 117:  Mag. 13.8.  Difficult object.  Seen at 125x and 150x.  Round.
eg 118:  Mag. 12.95.  Larger than 114, but seen with it at medium powers.  Large and fainter.
eg 120:  Mag. 13.35.  Threshold object at 125x.  Noticeably elongated at 150x.
eg 124:  Mag. 13.1.  Tricky to locate.  Big and oval, best with a.v.  Close to 114, 118.
eg 132:  Mag. 13.2.  Easy to spot at 60x!  Round and ghostly at 100x.  Much brighter at 200x, and quite large.  Sits amidst three faint stars.
eg 145:  Mag. 13.15.  Oval, faint and best with a.v. at 100x, 125x.
eg 161:  Mag. 13.35.  Like a star out of focus at 125x.  Very small.  150x shows elongation.  200x shows a stellar core.
eg 173:  Mag. 14.1.  Ghostly at 125x, it was acceptable at 150x and 200x.  Very large with a low surface brightness, I wish to return here for a 2nd look.
eg 179:  Mag. 13.05.  At -18 degrees.  Spotted at 100x.  Oval with a bright middle or perhaps a star within.  125x and 150x shows well.
eg 209:  Mag. 12.95.  1 degree S of 179!  Small, round and very faint.  Appears to have a stellar core.
eg 255:  Mag. 12.9.  Lying at -11 degrees, 28', this one has proved impossible up till my one fabulous night.  Easy tonight!  Round and ghostly, like a planetary nebula.  Large at 125x (though considerably smaller than nearby pn 246).
eg 1070: Mag. 12.75.  Seen at 60x, 100x, 125x and 150x.  Round, faint but large.  Oval at 150x.
eg 1085: Mag. 12.8.  Small and faint.  Should be brighter.  Will return for a 2nd look.
eg 1137: Mag. 13.  Views improve at 125x and 150x.  Considerably elongated using a.v.
eg 1153: Mag. 12.35.  Small and faint.  Oval at 150x, with a brighter middle.

CLUSTERS FROM OTHER CATALOGUES

Cassiopeia

oc Be 4:  15 faint stars around a bright one.
oc Be 61:  Small, hazy patch at 60x.  Resolves at 125x upward, but very few stars. 
oc Be 62:  A dozen faint stars involved with a 5-star asterism.  Use high power.
oc Be 104:  S of star V639.  6 stars resolved at 250x, hampered by the variable.
oc Do 13: Large and widely scattered group.  About 40 stars at 100x, many of them bright.  Attractive group.
oc King 1:  Very faint at 60x.  150x shows 16 stars in 2 groups.  A bright group is adjacent.
oc Skiff j00584+6878:  125x begins to show a dozen stars, widely scattered.  Out of the way.
oc St 18:  Line of 5 bright stars.  2nd from west surrounded by faint stars.
oc St 21:  A 'V'-shaped group was noted, open end to the NW.  The line of stars in the S (running E-W) has a compact group of very faint stars around it.  The whole 'V' is attractive.

Mapman

How Low Can You Go?

This short entry will discuss observing NGC objects near the horizon; in my case, towards the south and east.  My latitude is 42 degrees N, so that limits how far south I can see on a good night (it is next to useless to attempt low objects on a less-than decent night).  The fainter the object, the more difficult it is to see when it is down low.  A few objects recently attempted in Cetus have seen my scope pointed nearly horizontal.  If I were attempting to split a bright, wide double star, this would not pose too much of a problem.  Neither would locating a large, bright open cluster, or a large and bright globular cluster.  M 7 is way down there at -35 degrees, though it usually looks pretty fair from my site.  I have successfully observed down to -42 degrees, glimpsing oc 6231 in Scorpius one time with my 8".  That time the scope was flat out horizontal, and the cluster was at its highest point.  Omega Centauri, the globular cluster everyone wants to see at least once in their lifetime, has reportedly been seen from Point Pelee National Park by a member of our club, just a few miles from my location.  It lies below -47 degrees!!  Our local club (Windsor RASC) sponsors dark sky nights there once a month, and the south horizon view over Lake Erie can be very good.  This is the southern-most tip of mainland Canada, and lies at 41 degrees 55 minutes N latitude.

So those are the extremes.  For me, -42 degrees.  From my county (and country), -47 degrees.  But what about "normal" low horizon deep sky observing?  As mentioned, M 7 is getting pretty low, at -35 degrees.  Everything above that can be seen on a good night, with exceptions.  Below that, views can get very unsettled.  Very faint globulars are a problem, and then there are galaxies.  I have been researching my lowest easily obtained galaxies of late, and find that I must be pointing up pretty high to see the really faint ones.   Using Cetus as my example, here are some interesting tidbits.

Cetus drops to nearly -25 degrees.  I am not happy when I am observing galaxies down there, faint or otherwise.  Not only am I looking through a lot of atmosphere when my scope is pointed down that far, but southern sky light pollution turns that part of the sky a milky hue, making it impossible to see galaxies.  I have glimpsed eg 253, the Sculptor Galaxy, which lies just below -25 degrees.  It was not a showpiece sight, but it was viewable.  I have (barely) glimpsed eg 45 in Cetus.  This would be a tough object even if overhead, but its position at -23 degrees makes it a formidable task, even for a 12".  I have tried for years to glimpse this object, finally having success last month on a truly spectacular night.  My life is now nearly complete.

On that same night I also had my first really satisfactory view of pn 246.  It has a low surface brightness and lies at -12 degrees.  However, despite seeing perhaps a dozen brighter galaxies down there, it is hardly worth it.  It usually takes several attempts, and not much is seen except a ghostly haze.  Things begin to get more comfortable for me at around -8 degrees.  From here on up, even the dim galaxies begin to pop out.  From -6 degrees up, I am finally back to 100% certainty of locating almost any NGC object!

Finding out my low sky limitations has been enormously helpful.  I no longer waste precious time on cold nights trying to locate objects that are all but impossible from my location.  I have not given up on the more southerly objects, but will save them for a planned expedition to New Mexico next autumn.  Observing from 32 degrees N should make the job reasonably promising, along with darker skies.  Do you know your low sky limitations?  Try some brighter objects down there, and then slowly try for fainter and fainter, until there is... nothing.  Like me, you just might learn something!

Mapman Mike