A nice clear night last night (May 8 UT) motivated me to pack up my wife's 5" scope and head out to Doug Snyder's observatory for some deep sky observing. After setting up, I knocked off all the Messier objects and bright NGC galaxies on Tirion chart 2, on the understanding that you have to do something while you are dark adapting. About fifty minutes later, a run at several fainter galaxies in the area convinced me I was dark adapted sufficiently to try pushing the limits of scope and sky - with an observation of PK164+31.1 = Jones-Emberson 1.
The only hitch in the observation was that Mr. Brilliant forgot to mirror the finder charts he made for this object before printing them out. (The 5" scope is an AP-130 and is used with a diagonal for purposes of sanity and back health. Since it offers well over a 3 degree field with a low power eyepiece, the main scope is its own finder; only a Telrad is attached.) Although I used to be fluent at flipping, mirroring, and rotating charts mentally, too many years of computer charting software have apparently spoiled me.
Once the area of the planetary was found with a 28x/1.8 degree eyepiece, I looked casually for the planetary and couldn't scare it up. Switching to a 62x/42 minute eyepiece with a Lumicon UHC brought it out immediately. At first visible as only a faint, roughly circular smear, I took the time to guzzle some water (incipient dehydration does horrible things to my vision), get into a comfortable position, and center the object in the higher power field. Almost immediately it was clearly visible as a fat horseshoe, with the north side open, and the "ends" of the horseshoe somewhat fatter and brighter than the rest of it. Post facto it is pretty clear that the horseshoe ends were the brighter knots in the annulus, at pa 131 from each other.
Doug Snyder then walked over and came up with the "horseshoe" description on his own and agreed it looked fatter than the normal grade of horseshoe you see hanging (for good luck) in local restaurants of dubious quality.
Switching to an 87x/30 minute eyepiece with the UHC brought the planetary out in much of its detail, but only part of the time. The entire planetary was visible as an annulus about eighty percent of the time, and the brighter knots in the annulus were persistently visible at that magnification.
Increasing the magnification to 130x/20 minutes field did nothing for the planetary, with or without a filter, except making it harder to see.
We also tried a Lumicon OIII in various eyepieces (52x, 62x, 78x). This was an exercise in futility; the filter was probably too strong for the aperture and this particular object. Though the planetary was visible through it at 52x, it was on the fringes of visibility and no detail whatever was visible. Just focusing was a chore of prodigious difficulty.
Doug and I then had a peek at this planetary with his 20" scope and found that it is a really nice target at that aperture, being conspicuously visible, with a clear central star, some striation in the fainter parts of the annulus, and very clear knots which were more than just brightenings and thickenings of the annulus, one of which was definitely brighter or more compact than the other.
During these observations, stars of 15.4 V magnitude were visible in the 5" in the same general area of the sky as the planetary.
A good deal of my motive for posting this report is to respond to what was written about this object in June 2002 S&T, particularly the caption to the phot on pg. 104: "... Jones-Emberson 1 in Lynx is within reach of an 8" telescope. A larger scope, however, is needed to show the distinctive knots in the nebula's annulus." (I will note that the esteemed author properly hedged his bets in the actual article text.)
In addition to this challenging planetary and a bunch of stuff I've seen before, I logged observations of the following galaxies, also with the 5":
I failed at several others. I am trying to get an invisibility baseline worked up for this scope, and I definitely found the boundary last night. But I packed up satisfied that I had seen more with a 5" than most observers see with four times the diameter, and once again reflected that visibility limits are still - even after two decades of rolling them back - often expressed too conservatively.
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