Monday, August 13, 2007

20070811 - 10" into the Fall sky

Session name: 20070811.1920

Arriving at TotL before sunset with the Teleport 10" reflector is a sure way to gather a crowd. A congregation grows gradually while I leave the scope to acclimate to the outside temperature. People stop and wonder. The silvery, reflective cover that's velcroed to the side draws comments from cold beer to hot pizza. Soon enough even before it's dark a crowd of people assemble in a line to see Jupiter and his four moons. Omega Ophiuchi sits closeby as a fooler. The pedestrian traffic remained pretty steady until midnight as I watched the summer sky travel across the Manhattan skyline carrying Jupiter along with it.

Seeing was poor. Jupiter appeared as if it's on the bottom of the brook. Yet, a semi-regular and one of the only females, Nedia and myself witnessed Io ingress onto the jovian disk. We would lose it as it left the interior of the limb. My experience with observing ingresses and egresses is that the satellites' sun-facing side is much brighter than the jovian limb. Later with another couple, we watched the shadow ingress on the jovian disk around a 6 o'clock position in our field of view.

My original plan was to mimic Charlie's session from last week where he covered a lot of ground in summer constellations, Scorpio and Ophiuchus. But the steady traffic prevented me from locating and showing these objects. Showing fainter, more challenging objects in the city sky would be casting pearls before the swine. Observing DSOs in an urban sky is an acquired taste.

It feels as if a long time passed since I've observed deep sky objects. Usually equipped an equatorial-mounted Takahashi refractor I stay inside the solar system, especially with hazy, humid skies and short summer evenings. However, the weather forecast was positive and I decided on bringing out the 10" reflector.

I think this may have been the first time seeing M57 this year. It was so "bright" (in urban terms) that most could clearly see the smoke ring. M57, Jupiter and M31 (NGC224)/M32 (NGC221) were the three bright objects I showed to the public. For some, I showed M39 (NGC7092) and M29 (NGC6913) but these are not so spectacular; yet, it provided an opportunity to diversify the type of objects on display.

Charlie would arrive around midnight and the pedestrian traffic had thinned out. The Fall sky had risen appreciably in a clear dark "Corridor" to the north - northeast. Using 10" of glass, we looked outside of the solar system to outer reaches of our galaxy, and occasionally looking at others.

My observing began in earnest around this time. Details of observations in my logbook begin at this time starting with Caroline's Cluster, NGC7789. It's no wonder that this object is difficult in the 4" refractor. It appears mostly as a soft unresolved glow of stardust. The 10" glass improves the observation by showing a bed of fainter stars beneath strings of brighter stars that crisscross like diagonal of a rectangle. The stardust is more concentrated to the south. While in Cassiopeia, I dropped in on M52 (NGC7654). Usually, I drop the scope right on top of this cluster but rusty muscle memory made for a few unsuccessful attempts. Persistence and PleiadAtlas succeeded by finding one of the prettier clusters in the sky. Charlie and I commented about three levels of stellar brightness.

Similar to M110 (NGC205), the light of NGC6946, a galaxy in Cygnus, is too feeble to stimulate the rods of the eye distinct from the background sky. Only 39 arc minutes away, open cluster NGC6939 sits within the boundary of Cepheus and is more revealing to the eye. In medium powers it is still faint with 8 ~12 stars resolving.

Other open clusters we would observe through the night included NGC752, M34 (NGC1039), and NGC1528. These open clusters ranged from large, bright and sparse to fine, dusty and challenging. NGC1528 is located just off the Fish Hook, an asterism in Perseus. We use the Fish Hook as a test of naked eye limiting magnitude and sky transparency.

The usual route to the asterism Kemble's Cascade which hosts NGC1502, a pretty, little open cluster at the bird's foot, is to starhop from the Steeple of Perseus past a naked eye pair magnitude ~4.2+ stars. As I am looking in the eyepiece during this pan I search for the bright trail of stars. On this session, I stumbled upon Pazmino's Cluster (Stock23). This cluster reminds a little of M29 but much larger and just as bright. I'm struck with the same impression of an open box.

After observing Kemble's and the cluster, the last object we sought for the night was a nearby planetary nebula, NGC1501. I have a few observations of this PNe but it os difficult. We had the field of view, one which Sebastian depicts as we saw. Try as we did, we couldn't get the planetary to reveal itself beside the quadrilateral of stars to to the right.

As usual we were packed and the scanned the our urban night sky before leaving it to the day just beyond the horizon in the middle Winter sky. This was the opportunity to correct a mistaken identity. Originally, we identified the bright red object in the treetops as Aldebaran. At 3:30AM, the red star had risen higher above the trees with another red star below it. It was at this time we noted that Mars was situated midway between Pleiades and the Hyades.

Other objects we stopped on included the double Mesarthim, gamma Ari and triple Struve2816 & double Struve 2819 in the open cluster Trumpler37, IC1396. Spreading from the Garnet Star, mu Cep, TR37 appears as a large sparse collection of brighter stars upon a dim, resolving bed. I wouldn't call it rich nor did I see any nebulosity but that is a pretty triple out there in space.

Didn't mimic Charlie's hop but we panned for gold and took home the rich sights harvested from the Summer and Fall skies. In short time we'd be back at it with slightly different targets.