October 2, 2008

10pm – 1am

NGC 7635

Cassiopeia's famed “Bubble Nebula” is an emission nebula appearing not far from the open cluster M52. The conspicuous bubble feature results from “stellar wind,” a stream of charged gas, emanating from a nearby massive star. The gas from the star repels the nebula's own gas and dust creating the spherical structure, which uncannily resembles a soap bubble riding on the wispy froth of the rest of the gas cloud.

This image comprises 60, 30-second sub-exposures.

M74 

This is a spiral galaxy, seen face-on, about 35 million light years away in the constellation Picses.

This image comprises 80, 30-second sub-exposures.

M33

Another attempt at the Triangulum Galaxy (see September 23 post). 

This image comprised 80 21.2-second images.

M1

Better known to most amateur astronomers as the “Crab Nebula,” M1 is  remains of a star that went supernova (exploded) in 1054 AD. The supernova was observed on Earth by Chinese astronomers/astrologers who had no idea what they were actually seeing. The expanding cloud of gas, dust and other debris – now about ten light years across - was given its name by Lord Rosse, who sketched it in detail in 1844, noting an intricate filamentary structure.

In 1968, astronomers identified a pulsating radio source emanating from M1. This turned out to be one of  the first examples of a pulsar, a rapidly rotating neutron star. Neutron stars are composed of “degenerate matter” so densely packed that a spoonful would weigh 10,000 pounds. They result from the rapid collapse of matter under extreme gravitational forces during a supernova. A neutron star may only tens miles in diameter, but spins rapidly – 30 times per second, in the case of the Crab Nebula pulsar. 

This image comprises 30, 21.2 second images.

September 23, 2008

NGC 1491

This small emission nebula lies in the constellation Perseus and is illuminated by an 11^th magnitude star near is center. I imaged NGC 1491 using the .5 focal reducer, but the nebula's small size clearly demands another image taken at prime focus to provide more detail.

This image comprises 50, 15-second images.

M33

This is a large spiral galaxy located in the small – and usually unnoticed – constellation of Triangulum, which lies south of the better known constellations of Andromeda and Aries. M33 is often referred to as the Triangulum Galaxy.

After the Milky Way and Andromeda galaxies, M33 is the third largest member of the Local Group of galaxies, lying somewhat farther away than M31. Under very dark skies, it is possible to glimpse the large, but very faint light from this galaxy, making it perhaps the farthest object visible to the naked eye. But very, very dark skies and an exact knowledge of where to look is required to see it without optical aid. Even with a telescope or powerful binoculars, M33 is difficult to detect in light-polluted suburban skies.

This image comprises 80, 15-second images.

NGC 896

This a rather large emission nebula in the constellation Cassiopeia. The nebula is too large to be complete captured by the DSI Pro, even using the .5 focal reducer. Nevertheless, the camera did capture some of the brighter areas of the nebula, and some of the dark clouds of dust that run through it. The more diffuse parts of the nebula will likely require significantly longer exposure times. NGC 896 is actually a small part of a much larger complex of nebulae and open star clusters, whose other parts include IC 1805 and IC 1848.

This image is comprised of 60, 15-second sub-exposures.

NGC 891

This is a spiral galaxy seen edge-on. NGC 896 was first noticed by William Herschel in 1783; Herschel, of course, considered it simply another nebula. The galaxy, which can be easily detected in small telescopes as a faint cigar shaped smudge, lies about 27 million light years away in the constellation of Andromeda.

This image comprises approximately 80, 15-second sub-exposures.

M52

This wonderful open cluster is easily observed with binoculars as a faint cloud of light amid Cassiopeia's dense star fields. A small telescope will easily resolve the cluster into a glittering field of hundreds of stars. 

Charles Messier first noted the cluster in 1774 as he searched for comets in the skies over Paris. Modern estimates place the cluster about 5,000 light years away. It appears to span roughly 19 light years in diameter.  

The following image comprises 30, 15-second sub-exposures taken with the .5 focal reducer. Some vignetting is apparent.

NGC 205/M110 

This dwarf elliptical galaxy is a satellite of the much larger Andromeda Galaxy (M31). In small telescopes it can be seen as a small, fuzzy point next to the ghostly oval glow of M31 itself. Charles Messier noted the object in 1773 in his drawings of M31, but never officially added it to his catalog. Herschel recorded it ten years later. It was posthumously added to Messier's great catalog in 1966.

Elliptical galaxies assume a generally spherical shape. They display a marked lack of dust and gas. This means that elliptical galaxies exhibit  very little star formation; this, coupled with the radial rather than rotational motion of stars within these galaxies lends them a relatively featureless appearance. Large numbers of globular star clusters are often associated with older elliptical galaxies. 

NGC 869 & 884

If you poured diamonds of varying sizes into two piles close together on a dark velvet surface, you would be recreating, in miniature, the glorious appearance of the justly famed Perseus Double Cluster.

The double cluster is visible to the naked eye as a faint patch on the Cassiopeia-Perseus border and is easily seen on dark, chill autumn evenings. Binoculars can resolve the clusters into hundreds of glittering stars. The double cluster is best view with good binoculars or small scopes at low magnification (or using wide-field eyepieces) whose fields of view can easily encompass both clusters at once for the optimal visual effect.

Even with the .5 focal reducer, the DSI Pro cannot completely fit both clusters in its FOV. The following image, however, manages to capture the center of both clusters. It comprises 30, 15-second images.