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This article from Sky & Telescope discusses the accidental deep-sky discoveries made by American astronomer David Todd. While searching for a distant planet beyond Neptune, Todd stumbled upon several galaxies in the Leo and Virgo constellations. The article provides historical context, including predictions of a trans-Neptunian planet by other scientists, and describes Todd's visual search process. It also highlights the galaxies he discovered and their subsequent rediscovery by other astronomers. The article concludes with a brief mention of Todd's advocacy for the existence of intelligent life on Mars. [Extracted from the article]

Are you up for a deep-sky challenge? Start with this list of planetary nebulae. While a Caltech graduate student in the early 1950's, George O. Abell was given a research [...]

Halton Arp's Atlas of Peculiar Galaxies (1966) and Boris Vorontsov-Velyaminov's Atlas and Catalogue of Interacting Galaxies (1959) offer a sample of several hundred interacting and merging galaxies. Unlike symmetrical spiral [...]

Rare Red Planetaries In 1890, Fleming noted the unusual emission lines of Campbell's Hydrogen Star. FEATURES Snagging Planetary Nebulae Most of Fleming's planetaries are small - less than 15" in diameter - with high surface brightnesses. Many articles and books describe the rise to fame of maid-turned-astronomer Williamina "Mina" Paton Fleming (1857-1911) and her contributions to stellar classification. On a glass plate dated September 2, 1904, Mina discovered Fleming's Triangular Wisp, the third most prominent section of the Veil Nebula supernova remnant (see S&T: Sept. 2021, p. 28). [Extracted from the article]

What's the best-known star in the sky? Although it barely cracks the list of the 50 brightest stars, Polaris is certainly a top candidate. The 'North Star' has been an [...]

Observing the Fornax Dwarf presents a similar visual challenge as the Sculptor Dwarf, including the galaxy's very low surface brightness and southerly declination. OBSERVING In 1938, Harvard astronomer Harlow Shapley announced the discovery of a large but inconspicuous galaxy in Sculptor with an unusually low luminosity. Sculptor and Fornax The Sculptor Dwarf is a low-mass satellite of the Milky Way at a distance of 270,000 light-years. [Extracted from the article]

Rich galaxy clusters vary significantly in the distribution of galaxy types, the degree of central concentration, and whether there is a single dominant member. In some clusters a central ultra-luminous [...]

Galaxies all shine with a constant luminosity, right? That assumption was shown to be false in 1965 when California Institute of Technology astronomer Fritz Zwicky discovered an unusual, variable object [...]

Galaxies are social creatures--they'll congregate in groups of any size from pairs and threesomes, to clusters and superclusters. Dedicated observers of galaxy groups are familiar with Paul Hickson's Compact Groups [...]

The FEBRUARY SKY IS HOME to several of the season's top planetary nebulae. These ephemeral celestial gas bubbles are among the most beautiful and fascinating objects in the sky. Many [...]

USEFUL SOURCES Halton Arp's Atlas of Peculiar Galaxies (1966) and Boris Vorontsov-Velyaminov's The Atlas and Catalogue of Interacting Galaxies (1959) contain many examples of photogenic M2 and M3 mergers such as The Antennae (NGC 4038-39) and The Mice (NGC 4676). The northern galaxy's infrared emission surpasses 500 billion times that of our Sun's, while massive star clusters line the spiral arms of the southern galaxy. ARP 240 This glorious duo in Virgo comprises NGC 5257 (right) and NGC 5258 (left), spirals that are very similar both in mass and size. FEATURES Galactic mergers play a key role in the formation and evolution of galaxies, with the most spectacular examples involving massive, gas-rich spirals. [Extracted from the article]

M101 shows a wealth of detail through moderate- and large-aperture telescopes under dark skies. AT A DISTANCE of about 25 million light-years, M101 in Ursa Major is one of the [...]

The NGC/IC Project is cleaning up vast numbers of mistaken identities, lost objects, and other mysteries in astronomy's most important deep-sky catalogs. LIKE MOST AMATEURS CUTTING their teeth on visual [...]

The Palomar observatory Sky Survey, conducted from 1949 to 1956 using the 48-inch Oschin Schmidt Telescope, recorded stars as faint as 21st magnitude, along with countless deep-sky objects. The 936 [...]

The Sagittarius Dwarf Galaxy Stream Three Milky Way globular clusters, two open clusters, and a planetary nebula are one-time members of the dwarf galaxy and are now sailing along its stream. Planetary Nebulae Astronomer-turned-astronaut Karl Henize discovered Hen 2-436 in 1954 during an Ha survey of emission stars and nebulae in the southern Milky Way. NOT ONE OF OUR OWN Charles Messier discovered M54 in 1778, but it wasn't until 1994 that astronomers realized that the globular cluster didn't originate in the Milky Way but was in fact formerly a member of another galaxy. [Extracted from the article]

An exotic collection of galaxies awaits observers willing to tackle the southern sky. WILLIAM HERSCHEL, POSSIBLY history's greatest deep-sky observer, began a systematic visual survey of the heavens in late-18th-century […]

I ENJOY SEEING A LOT OF GALAXY ACTION in the eyepiece. From interacting pairs to rich clusters spilling over several eyepiece fields--the more galaxies in view, the merrier! Galaxies like [...]

Spice up your observing sessions by taking a tour of a dozen often overlooked springtime galaxies. These objects are just as impressive at the eyepiece as those with a Messier [...]

English astronomer William Herschel began his survey of the heavens in 1783. He encountered several small, striking, symmetrical nebulae. They looked similar to Uranus' blue-green disk Herschel had discovered in [...]

The nebula is probably not an emission nebula, but a reflexion nebula which obscures the peculiar star by which it is illuminated." OBSERVING Before producing the beautiful glowing shells of planetary nebulae, low- to intermediate-mass stars (0.8 to 8 solar masses) eventually exhaust their core fuel supply of hydrogen and helium. One Tiny Footprint In 1946, German-American Germa astronomer mer Rudolph Minkowski began a survey of planetary nebulae using objective-prism survey plates at Mount Wilson Observatory. The nebula lies in a dense Milky Way field, but an orange 10th-magnitude star just 30" to the west highlights the spot. [Extracted from the article]

A violent event called a supernova happens in a galaxy once or twice a century. A star heavier than about 12 solar masses ends its brief life span in a [...]

In 1867, Paris Observatory astronomers Charles Wolf and Georges Rayet uncovered a mystery they could not solve. While scanning the constellation Cygnus with a visual-prism spectroscope, they discovered three 8th-magnitude [...]

M83, THE GORGEOUS Southern Pinwheel, ranks high on my all-time favorites list. Shining at magnitude 7.5, M83 is the 4th-brightest Messier galaxy after M31, M33, and M81. And at a [...]

Any list of favorite summer deep-sky objects is certain to include globular clusters such as M4, M5, M13, M15, and M22. However, adventurous observers willing to dig deeper will find [...]

These are exciting times for deep-sky observers. Many objects rarely observed just a few decades ago have become familiar telescopic sights at today's star parties. For example, the Veil, Eagle, [...]

Galaxies are gregarious. On every scale they tend to huddle with neighbors, beginning with pairs and small groups and extending on up to rich clusters containing hundreds of members and [...]

THE SPIRAL GALAXY NGC 6946 is the most productive supernova factory of the past century. Since the last Milky Way supernova explosion 140 years ago, NGC 6946 has churned out [...]

WHAT'S THE BRIGHTEST northern galaxy not included in the Messier catalog? You might be surprised to hear that distinction belongs to 8.4-magnitude NGC 2403, a prominent spiral that would be [...]

SADR (GAMMA CYGNI) may have won a celestial lottery for one of the prime locations in the sky. It marks the breast of the celestial Swan and the center of [...]

WOLF-RAYET STARS are extremely massive, hot, and luminous, with spectra dominated by unusually strong emission lines. Only 300 have been discovered in our galaxy, and their ultimate fate is to [...]

TUCKED IN the southeastern corner of Cassiopeia are the immense H II regions IC 1805 and IC 1848, popularly known as the Heart and Soul Nebulae. These faintly glowing clouds [...]

When the plane of a spiral galaxy tilts directly toward our line of sight, the edge-on perspective can provide a breathtaking view of the bright central bulge and equatorial dust [...]

The article discusses the Hydra I Cluster or the Abell 1060 which is one of the nearest rich galaxy clusters beyond the Virgo Cluster with having the same resemblance. It states that Hydra I is three times as distant as the Virgo cluster and that each cluster contains 50 galaxies within two magnitudes of their dominant members, M87 in Virgo and NGC 3311 in Hydra and with supergiant ellipticals with comparable absolute magnitudes.

March begins the season for galaxy hunting in the Northern Hemisphere with a countless supply of targets stretching from Ursa Major in the north to Centaurus in the south. As [...]

The article cites George O. Abell who published a list of 73 Abell planetaries in 1955. A comprehensive study titled "Properties of Some Old Planetary Nebulae," has been published by Abell in the Astrophysical Journal in 1966 as a follow up to his list. There are 86 objects north of -35 degrees declination in Abell's final catalog, and some turned out to be plate flaws and imposters.

The article discusses images of interacting and merging galaxies including tidal tails, bridges and starbursts captured using the 48-inch f/4 telescope of Jimi Lowrey in West Texas and featured in the "Atlas of Peculiar Galaxies," by Halton Arp and "Atlas and Catalogue of Interacting Galaxies," by Boris Vorontsov-Velyaminov. Topics include the Arp 142 (VV 316), the Arp 188 that shows a severely deformed 13.7-magnitude Theta Draconis, and the Arp 242 (VV 224).

The article focuses on the Corona Borealis Cluster that features several hundred elliptical (E) and lenticular (S0) galaxies packed into a 30′ circle, the size of the full Moon. It mentions a study using the Gemini South telescope revealed ESO 146-5 has gravitationally lensed a background galaxy at 2.5 billion light-years. It informs that CTA 102 is classified as an optically violent variable quasar as it contains high-energy plasma jets launched from a supermassive black hole.

If you're looking to expand your observing horizons beyond the standard cast of star-party favorites, consider compact galaxy groups. They form challenging yet rewarding observing projects for those with fairly [...]

Photographs of galaxies, such as those gracing this magazine, show some of the most beautiful and intriguing objects in the universe. The majestic whorls of spirals, the vast gatherings of [...]

Spend an enjoyable spring night getting to know some of the sky's tightest galaxy groupings. For many deep-sky observers, compact galaxy groups are a special source of fascination. Who can [...]