Aperture? Who needs it?

Montebello, Oct 22 1997

Despite threats of fog, the 10/22/97 TAC star party at Montebello OSP was well attended, perhaps ten people.

I had brought my 80mm Celestron/Vixen refractor, expecting an evening of mostly planetary observing with poor chances of dark-sky observing due to the light fog.

But when the seeing proved quite unsteady (I could barely make out Cassini's division in Saturn's rings), I thought about a recent 80mm owner's query on sci.astro.amateur, "Is my telescope useful for dark-sky observing?", and decided to find out, despite the fog, occasional clouds, and the silicon valley light dome.

My first deep-sky target was the ring nebula -- I bought the 80mm as a planetary 'scope, so why not look at a planetary? The ring was easily visible through a 7.5mm Tak eyepiece (121x), but not as sharp as I had hoped, probably due to the unsteady seeing. Adding a UHC filter didn't help at all, to my surprise.

I looked at a few of my favorite open clusters: M11 sparkled, though of course it showed fewer stars than are visible through a larger aperture; NGC 457, which I've always known as the "dragonfly", showed nicely; and with a 25mm Plossl, the Double Cluster in Perseus was gorgeous, with both clusters visible.

While I was in the area, I turned to M31. The main galaxy and M32 showed very well, though the dust lane wasn't obvious in the 80mm. M110 was also easily visible, and I could detect a trace of brightening in the area of the star cloud NGC 206.

A nearby observer with a 4.5" was looking at M22, low in the southwestern sky, so I pointed there as well, and was rewarded with an excellent view of the globular.

Then both of us moved to the Veil nebula, not expecting anything particularly impressive with our small-aperture telescopes. But we were mistaken -- the views of the Veil, even through the 80mm from a bright-sky site, were quite impressive. I was using a 20mm Erfle (45x) with a UHC filter; the 4.5" owner was using a 25mm Plossl (36x) with an OIII filter. We wondered how the different filters and magnifications might be affecting things, so we tried trading eyepieces (the 4.5" and the 80mm have almost the same focal length). I thought the OIII was doing slightly better on the Veil, which corresponds to my past impressions, though we both agreed that 20mm Erfle gave a better view than the 25mm Plossl (they have almost the same actual field size). The 4.5" showed more filamentary structure in the nebula, but the 80mm gave a darker sky background.

I rounded out my deep-sky observations with a look at the Dumbell with a 15mm Panoptic (60x) and the UHC filter -- the view was excellent, with the "apple core" shape clearly visible, as well as the fainter outer edges and the brightness variations outside the "core". Then I went back to the planets to see whether the seeing had improved any -- it had somewhat, and I was able to pump the 80mm up to 180x (5mm Ultrascopic) on Saturn and get a good look at Cassini's division and the bands on the planet, though I wasn't able to pick out the Crepe Ring, which is usually visible with this telescope on better nights.

The clouds were coming in again, so I packed up and called it a night, surprised and pleased at how well the little refractor had done. Aperture? Who needs it?

Akkana Peck ; last updated: 1997 Oct 24