Giovanni Maria Cassini  

Planisfero Celeste Meridionale, calcolato per il corrente anno MDCCXC, Aggiuntevi le 14 nuove Costellazioni osservate dal Sig.r de la Caille al Capo di Buona Speranza.  Roma, presso la Calcografia Camerale, 1790  

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Giovanni Maria Cassini (1745-1824), Chierico Regolare Somasco, discepolo di Giovanni Battista Piranesi,   fu geografo, cartografo e incisore operante a Roma nei decenni a cavallo tra il diciottesimo e il diciannovesimo secolo. A lui si deve l'invenzione di un nuovo metodo di proiezione, detto appunto di Cassini, utilizzato anche per la realizzazione dell’atlante geografico del regno di Napoli in 32 fogli firmato da Giovanni Antonio Rizzi Zannoni.

Tra le sue opere maggiori, oltre ad  una carta generale dell'Italia in 15 fogli pubblicata nel 1793, troviamo il Nuovo Atlante Geografico Universale in tre volumi edito a Roma dal 1792  al 1801 le cui tavole del primo volume sono precedute da un breve saggio introduttivo sullo studio della geografia e che si propone inoltre lo scopo di  delineare il metodo seguito per la realizzazione dell'atlante stesso. L' opera venne commissionata dalla Calcografia Camerale di Roma  al fine di sostituire l'ormai superato Mercurio Geografico in uso nei decenni precedenti. Il Cassini firma tutte le carte come incisore.

 Le tavole introduttive del primo volume trattano argomenti di geografia generale e astronomica, tra queste si evidenziano per la loro bellezza  i due planisferi celesti editi già nel 1790.

Sono invece del 1792 le cinque tavole (43,7 x 57,7 cm ), attualmente rarissime e ricercate opere d’antiquariato, che riproducono i dodici spicchi di 30 gradi di A. R. d’ampiezza che, una volta ritagliati e incollati su di una sfera di legno e cartone, compongono l’intero globo celeste; nel cartiglio posto al centro di uno degli spicchi, tra Boote e il Monte Menalo, si legge “GLOBO CELESTE Calcolato per il corrente anno sulle Osservazioni de’ Sigg. Flamsteed, e de la Caille. ROMA presso la Calc.a Cam.le 1792

Il Planisfero Celeste Meridionale è una tavola di 33 x 45,6 cm ,  tutti i testi riportati sono in lingua italiana dell’epoca. Il cielo è incluso entro un cerchio di 29,4 cm avente per centro la proiezione del Polo Sud Celeste e per circonferenza  quella dell’equatore celeste. Le costellazioni sono riprodotte tramite una proiezione stereografica polare concava e comprendono stelle, posizionate per l’anno 1790, distinte in sei classi di grandezza oltre ad alcune nebulose. Il reticolo di riferimento, incentrato sul Polo Sud Celeste, comprende cerchi di declinazione disegnati ogni 10 gradi, tra questi sono evidenziati  il Circolo Polare Antartico ed il Tropico del Capricorno, le linee di ascensione retta partenti dal Polo Sud intersecano la circonferenza dell’ equatore ogni 10 gradi e sono numerate progressivamente, l’equatore è distinto in tacche di un grado di A. R. di ampiezza. Anche la parte di eclittica visibile è suddivisa in tacche di un grado di longitudine; la numerazione che va  di dieci in dieci ricomincia da capo ogni 30 gradi onde identificare con precisione la zona di appartenenza delle diverse costellazioni zodiacali identificate anche dal loro simbolo grafico.

Nella tavola vengono disegnate numerose costellazioni non tolemaiche, Antinoo, la Colomba, la Croce, con il termine la Nuvola le due nubi di Magellano, il Liocorno, il Sestante, lo Scudo di Sobieski, le dodici costellazioni di Bayer-Keyser-Houtman, le quattordici (quindici se gli si accredita la Musca) di Lacaille e il Solitarius di Le Monnier denominato in italiano il Passero. Anche alcune stelle vengono segnalate con il loro nome proprio: Antares nello Scorpione, Spica nella Vergine, Phomalaut nel Pesce Australe, Achernar nel Rodano (con questo nome l’autore dà una sua interpretazione dell’Eridanus), Canopo nella Nave, Rigel in Orione e Sirio nel Cane Maggiore. Differentemente da quanto avviene per il Planisfero Settentrionale sono numerose le nebulose segnalate, come quelle in Scorpione, Indiano, Toucan, Centauro, Nave, Altare.  Le stelle più luminose sono identificate da lettere greche secondo il metodo di Bayer. La Via Lattea è nominata e disegnata con precisione.

All’esterno del planisfero, agli angoli della carta, probabilmente su ispirazione delle tavole incise poco più di un ventennio prima da G. Zuliani a Venezia per conto di Antonio Zatta, sono disegnate le facciate degli edifici di quattro dei maggiori osservatori europei: la Specola di Parigi, la Specola di Cassel, la Specola di Greenwich e la Specola di Coppenaghen. Oltre alla scala delle grandezze delle stelle Cassini predispone infine tre barre che hanno la funzione di essere colorate con gli stessi colori che il pittore  utilizzerà per  distinguere le costellazioni antiche da quelle recenti e da quelle di La Caille, le carte infatti erano stampate in bianco e nero e soltanto successivamente venivano colorate a mano, generalmente con acquerelli.   

LE NEBULOSE

(in costruzione)

Cassini indica almeno dodici oggetti con il simbolo dedicato alle Nebulose, otto dei quali dislocati nella Via Lattea. Nel planisfero seguente sono sottolineati con un tratto rosso.   

Ho cercato di identificare gli oggetti indicati dal Cassini confrontando gli ingrandimenti della sua tavola con altrettante ricostruzioni operate con il programma Perseus. Il centro di ogni carta di Perseus, costruite per l'equinozio del 1790, coincide con le coordinate del relativo oggetto in questione che ho rilevato graficamente dalla Mappa di Cassini. Non ci sono stati problemi per le declinazioni, per l'Ascensione Retta ho dovuto invece trasformare in ore e minuti  il valore che l'autore indica in gradi sessagesimali.

 Nebulosa tra la Poppa della Nave e il Cane Maggiore

Coordinate del Cassini: Declinazione 37° Sud circa. Ascensione Retta 113,5° circa

Coordinate Perseus: Declinazione 37° Sud circa. Ascensione Retta 113,5° =7h 33'circa

 La Nebulosa in oggetto  potrebbe pertanto essere l'Ammasso Aperto NGC 2451 di Mv 2,79 scoperto da Hodierna nel 1654 oppure l'Ammasso Aperto NGC 2477 di Mv 5,79 scoperto da Lacaille tra il 1751 e il 1752.

NGC 2451

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Last Modification: March 12, 1998

 

Open Cluster NGC 2451 (= Collinder 161) in Puppis

Right Ascension	07 : 45.4 (h:m)
Declination	-37 : 58 (deg:m)
Distance	0.85 (kly)
Visual Brightness	2.8 (mag)
Apparent Dimension	45 (arc min)

Discovered by Hodierna before 1654.

This cluster was probably another one discovered by Hodierna. Because of its southern declination, northern observers including Charles Messier and William Herschel could not find it.

NGC 2451 consists of 40 stars, the brightest of which (c Puppis) is a yellowish giant of magnitude 3.6, and the hottest of which is of spectral type B8. Its age was estimated at 36 million years, and it is receding from us at 26 km/sec. At only about 850 light years, this cluster is quite close to us.

The image in this page was obtained by Matt BenDaniel. It was cropped from a larger image which shows NGC 2451 together with its apparent neighbor, NGC 2477. This is a 60-minutes exposure on Kodak E 200 film, taken with a Tele Vue 85 refractor at f/5.6, on December 31, 2000 at 00:23 PST. More information on this image (Matt BenDaniel) More images from Matt BenDaniel

In John Caldwell's List and in the Astronomical League's Southern Sky Binocular Club List.

• Jean-Claude Mermilliod's WEBDA cluster page for NGC 2451
• SIMBAD Data of NGC 2451
• Publications on NGC 2451 (NASA ADS)
• Observing Reports for NGC 2451 (IAAC Netastrocatalog)
• NGC Online data for NGC 2451
• 
  

NGC 2477

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Open Cluster NGC 2477 (= Lacaille I.3 = Dunlop 535), type 'g', in Puppis

Right Ascension	07 : 52.3 (h:m)
Declination	-38 : 33 (deg:m)
Distance	4.2 (kly)
Visual Brightness	5.8 (mag)
Apparent Dimension	27 (arc min)

Discovered by Lacaille 1751-52.

This cluster was discovered by Abbe Lacaille when he was in South Africa during 1751-1752.

Burnham states this is "probably the finest of the galactic clusters in Puppis," but not in Messier's catalog and many other observing lists as it is situated to much south. However, where it comes sufficiently high over the horizon, it is a splendid rich cluster of over 300 stars, crowded in a 20' field, situated about 2.5 deg NW from 2.25 mag, extremely hot O5 supergiant Zeta Puppis (this star, at 2,400 light years distance, is one of the brightest stars known, with absolute mag -7.1, corresponding to 60,000 solar luminosities).

The brightest star of NGC 2477 is of mag 9.81, the hottest of spectral type B8. The cluster's age has been estimated at about 700 million years (Sky Catalog 2000.0).

The image in this page was obtained by Matt BenDaniel. It was cropped from a larger image which shows NGC 2477 together with its much nearer apparent neighbor, NGC 2451. This is a 60-minutes exposure on Kodak E 200 film, taken with a Tele Vue 85 refractor at f/5.6, on December 31, 2000 at 00:23 PST. More information on this image (Matt BenDaniel) More images from Matt BenDaniel

In the Astronomical League's Southern Sky Binocular Club list. Caldwell 71 in Patrick Moore's list.

Investigations of the stars of NGC 2477 has lead, in November 2003, to the discovery of the Canis Major Dwarf, the closest dwarf galaxy to us and our Milky Way.

• Jean-Claude Mermilliod's WEBDA cluster page for NGC 2477
• SIMBAD Data of NGC 2477
• Publications on NGC 2477 (NASA ADS)
• Observing Reports for NGC 2477 (IAAC Netastrocatalog)
• NGC Online data for NGC 2477
  

Nebulosa presso la stella Epsilon (Avior Epsilon Carinae) della Nave

Coordinate del Cassini: Declinazione 58° Sud circa. Ascensione Retta 108° circa

Coordinate Perseus: Declinazione 58° Sud circa. Ascensione Retta 108°  = 7h 12'circa

La Nebulosa in oggetto  potrebbe pertanto essere l'Ammasso Aperto NGC 2516 di Mv 3,79 scoperto da Lacaille tra il 1751 e il 1752

NGC 2516

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Open Cluster NGC 2516 (= Lacaille II.3 = Melotte 82 = Collinder 172), in Carina

 

Right Ascension	07 : 58.3 (h:m)
Declination	-60 : 52 (deg:m)
Distance	1.3 (kly)
Visual Brightness	3.8 (mag)
Apparent Dimension	30 (arc min)

Discovered 1751-52 by Lacaille.

Southern open cluster NGC 2516 was discovered by Abbe Lacaille in 1751-1752 from South Africa.

In the Astronomical League's Southern Sky Binocular Club list. In John Caldwell's List. Caldwell 96 in Patrick Moore's list.

Jean-Claude Mermilliod's WEBDA cluster page for NGC 2516 SIMBAD Data of NGC 2516 Publications on NGC 2516 (NASA ADS) Observing Reports for NGC 2516 (IAAC Netastrocatalog) NGC Online data for NGC 2516

Nebulosa presso le stelle Iota (Aspidiske o Iota Carinae) e Kappa (Kappa Velorum)  della Nave

Coordinate del Cassini: Declinazione 57° Sud circa. Ascensione Retta 137° circa

Coordinate Perseus: Declinazione 57° Sud circa. Ascensione Retta 137° = 9h 42' circa

Alle coordinate corrispondenti al punto indicato da Cassini non vi sono oggetti non stellari particolarmente luminosi. Nei pressi troviamo NGC 2867, una Nebulosa Planetaria piuttosto debole per essere la nostra candidata, inoltre venne scoperta da Herschel soltanto nel 1834, dopo la realizzazione della mappa del Cassini. Rimane pertanto IC 2488 di A. R. 9h 21', un ammasso aperto di Mv 7,40 scoperto da Lacaille nel 1752, accettando il quale dobbiamo però addebitare a Cassini un sensibile errore di precisione nel disegnarlo.

 

Right Ascension	09 : 27.6 (h:m)
Declination	-56 : 59 (deg:m)
Brightness	7.4p (mag)
Apparent Dimension	15 (arc min)

Discovered by Lacaille in 1752.

Southern open cluster IC 2488 was discovered by Abbe Lacaille on January 25, 1752 from South Africa and cataloged as Lacaille III.4.

Jean-Claude Mermilliod's WEBDA cluster page for IC 2488 SIMBAD Data of IC 2488 Publications on IC 2488 (NASA ADS) Observing Reports for IC 2488 (IAAC Netastrocatalog) NGC Online data for IC 2488

Nebulosa presso la stella Eta della Nave

Coordinate del Cassini: Declinazione 54° Sud circa. Ascensione Retta 164,5° circa

Coordinate Perseus: Declinazione 54° Sud circa. Ascensione Retta 164,5°  = 10h 58'circa

L' oggetto più vicino alla posizione indicata da Cassini è l'Ammasso Aperto NGC 3532 di Mv 3,0 scoperto da Lacaille nel 1752

NGC 3532

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NGC 3532

Dreyer's description: !!, Cl, eL, R, lC, st 8...12

Cross Identifications: GC 2308, h 3315, Lac 2.10, Dun 323. 5 Cen, Mel 103, Cr 238 .

More on NGC 3532

Right Ascension:	11 : 06.4 (hours : minutes)
Declination:	-58 : 40 (degrees : minutes)
Apparent Magnitude:	3.0
Apparent Diameter:	55. (arc minutes)

NGC Home NGC 3531 | NGC 3533

• Digital Sky Survey image
• Revised NGC/IC data
• NGC/IC data
• SIMBAD data
• HST Archive images
• NED data
• Publications and References (ADS)
• Observing Reports (IAAC Netastrocatalog)

Nebulosa presso le stelle Xi e Zeta Centauri 

Coordinate del Cassini: Declinazione 48° Sud circa. Ascensione Retta 197,5° circa

Coordinate Perseus: Declinazione 48° Sud circa. Ascensione Retta 197,5°  = 13h 9'circa

Si tratta dell'ammasso Globulare visibile senza strumenti Omega Centauri, NGC 5139, di magnitudine apparente 3,7 scoperto da E. Halley nel 1677.

NGC 5139

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Right Ascension	13 : 26.8 (h:m)
Declination	-47 : 29 (deg:m)
Distance	16.0 (kly)
Visual Brightness	3.68 (mag)
Apparent Dimension	36.3 (arc min)

Discovered by Edmond Halley in 1677.

This is the biggest of all globular clusters in our Milky Way galaxy. With its about 5 million solar masses, it is about 10 times as massive as other big globulars, and has about the same mass as the smallest whole galaxies. It is also the most luminous Milky Way globular, and the brightest globular cluster in the sky. In the Local Group, it is outshined only by the brightest globular cluster G1 in the Andromeda Galaxy M31.

In 1999, a team led by Young-Wook Lee of Yonsei University, South Korea, obtained a color-magnitude diagram (CMD) for 50,000 member stars of Omega Centauri with the 0.9-m telescope of CTIO in Chile. Studies of this CMD indicate that the stars of this cluster did not all form at once but over a 2-billion-year period of time, with several starburst peaks. This was the first time that multiple populations were found in a globular cluster. The team who carried out this work speculates that this result may indicate that Omega Centauri might be the remnant of a nucleus of a small galaxy which has merged with our Milky Way.

The image in this page was obtained by David Malin with the Anglo-Australian Telescope. This image is copyrighted and may be used for private purpose only. For any other kind of use, including internet mirroring and storing on CD-ROM, please contact the Photo Permissions Department (photo at aaoepp.aao.gov.au) of the Anglo Australian Observatory. More information on this image by David Malin

Omega Centauri had been listed in Ptolemy's catalog as a star. Halley was the first to document its nonstellar nature, and listed it as "luminous spot or patch in Centaurus" in his historical list of six such objects. Lacaille included it in his catalog as number I.5.

In the SAC 110 best NGC object list. In John Caldwell's observing list. In the Astronomical League's Southern Sky Binocular Club list. Caldwell 80.

• Multispectral Image Collection of Omega Centauri, SIRTF Multiwavelength Messier Museum
• Marco Castellani's data for NGC 5139
• SIMBAD Data of NGC 5139
• Publications on NGC 5139 (NASA ADS)
• Observing Reports for NGC 5139 (IAAC Netastrocatalog)
• NGC Online data for NGC 5139
  

Nebulosa tra le stelle Teta Centauri e Pi e Gamma Hydrae

Coordinate del Cassini: Declinazione 27,5° Sud circa. Ascensione Retta 200,5° circa

Coordinate Perseus: Declinazione 27,5° Sud circa. Ascensione Retta 200,5°  = 13h 22'circa

Si tratta della Galassia Spirale NGC5236 scoperta da Lacaille nel 1752 e introdotta da Messier nel suo catalogo con la classificazione M83

NGC 5236 M83

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Right Ascension	13 : 37.0 (h:m)
Declination	-29 : 52 (deg:m)
Distance	15000 (kly)
Visual Brightness	7.6 (mag)
Apparent Dimension	11x10 (arc min)

Discovered 1752 by Nicholas Louis de Lacaille.

Messier 83 (M83, NGC 5236) is one of the most conspicuous spiral galaxies in the sky. Situated in constellation Hydra, it is the southernmost galaxy in Messier's catalog.

M83 was discovered by Nicholas Louis de Lacaille at the Cape of Good Hope on February 23, 1752; it was his object Lacaille I.6. Thus it became the first galaxy to be discovered beyond the Local Group, and the third of all galaixes, after M31 and M32. It was next cataloged by Charles Messier on February 17, 1781; from his mid-northern location in Paris (at 49 degrees Northern latitude), it is such a difficult object that he stated that: "One is only able with the greatest concentration to see it at all." The present author can confirm it is one of the most difficult Messier objects from South Germany. Due to this fact, older Northern-compiled catalogs tended to underestimate its brightness considerably; e.g., Becvar has it at a mere 10.1 mag only.

Early 19th century Australian observer James Dunlop has it as No. 628 in his catalog. Its spiral structure was noted and sketched by William Lassell who described it as a "three-branched spiral."

M83 was classified as intermediate between normal and barred spiral galaxies by G. de Vaucouleurs, in his classification this is SAB(s)c. It is magnificient in our image, has very well defined spiral arms and displays a very dynamic appearance, appealing by the red and blue knots tracing the arms. The red knots are apparently diffuse gaseous nebulae in which star formation is just taking place, and which are excited to shine by its very hot young stars. The blue regions represent young stellar populations which have formed shortly (i.e., some million or some dozens of million years ago). Between the pronounced spiral arms are regions with fewer stars. Dark dust lanes follow the spiral structure throughout the disk, and may be traced well into the central region to the nucleus, which has only 20" diameter. This nucleus shows strong emission lines. It is composed of an older yellowish stellar population which dominates the whole central region, and extends along the barlike structure.

Our image was obtained by David Malin with the 3.9-meter Anglo-Australian Telescope of the Anglo-Australian Observatory. Interested parties can get more detailed information on this image. Also available are more images of M83 with the same telescope.

David Malin, in his older publications, always gave a distance of about 25 million light years, as he does in his book A View of the Universe in chapter 4, while in his Galaxies chapter 8, he joins the lot of those claiming a distance of about 10 million light years, and gives an argument, namely that the brightest stars can be viewed as individuals over this distance. M83 recedes at 337 km/sec, implying a bit larger distance from Hubble's law (H0=75 yields about 15 million light years, uncorrected for the disturbation by the Virgo cluster of galaxies, the Virgo centric flow, but in excellent agreement with the value of 15.3 million light years given in R. Brent Tully's Nearby Galaxies Catalog). Kepple/Sanner give another deviating distance value of 22 million ly.

This galaxy is sometimes called the "Southern Pinwheel". It forms a small physical group, the M83 group, with the peculiar radio galaxy Centaurus A (NGC 5128) and the unusual galaxy NGC 5253 in Centaurus. R. Brent Tully also lists the following smaller and fainter presumable (or possible) members of this group: NGC 4945, NGC 5102, NGC 5164, NGC 5408, ESO 381-20 (MCG-6-28-017; 1243-33), ESO 324-24 (MCG-6-30-003; 1324-41), ESO 444-84 (MCG-5-32-000; 1334-27), ESO 325-11 (1342-41), and ESO 383-87 (MCG-6-30-025; 1346-35).

Five or six supernovae were reported in M83 up to now:

• 1923A was observed by C.O. Lampland at Lowell Observatory at mag 14.
• 1945B appeared on July 13, 1945 and reached mag 14.2). This supernova was only detected in 1990 by W. Liller on photographic plates taken at Harvard's station at Bloemfontein (South Africa), and could be traced from July 13 to August 7 (see IAU Circular 5091).
• 1950B was observed by G. Haro and reached mag 14.5 in its maximum,
• 1957D was discovered by H.S. Gates on December 13, 1957 and reached only mag 15.0, it was about 3' NNE of the nucleus.
• Supernova 1968L was discovered visually by amateur astronomer Jack C. Bennett of Pretoria, South Africa, when sweeping for comets; this was a type I, located 5" preceding the nucleus and reached mag 11 to 12.
• 1983N appeared on July 3, 1983 and became as bright as 12.5 mag.

For years, M83 had been the galaxy with most discovered supernovae, but semi-recently NGC 6946 passed this mark and at the time of this writing (March 2009), holds the current record with a total number of 9. Moreover, M61 has now also caught up and equalled the mark of six supernovae in late 2008.

M83 is one of the showpieces in the southern deep sky, but difficult for mid-northern observers, as already stated. It is even rather difficult to find: First locate one of the stars Gamma or Pi Hydrae. It can be found either by star hopping from Gamma Hydrae (mag 3.00, spectral type G5 III) which is 6.5 deg N and 3deg 15' (19 min in RA) W, or from Pi Hydrae (3.27 mag, spectral type K2 III) from which M83 is about 3deg 15' S and 6deg 20' W. Following a trail of 5th to 7th mag stars, one arrives at a yellowish 5.83-mag star of spectral type F6 and a mag 7.0 white star (spectrum A5 V) which lie about 30' NE of M83. Star hopping from Gamma will bring you close to NGC 5061 (H 1.138), an elliptical galaxy of mag 10.2.

Southerners may find it easier by locating M83 from the constellation Centaurus, as it is just north of the border from Hydra to this constellation. From Iota and Theta Centauri, in the Head of the Centaurus figure, locate the stars i, h and k (mentioned by Messier) as well as g Centauri, all between mag 4 and 5; they are also known as 1 i Cen, 2 g Cen, 3 k Cen, and 4 h Cen. g and i just point to M83 (and further to Gamma Hydrae); the galaxy comes beyond i, at double distance from it than has g.

Historical Observations and Descriptions of M83 More Anglo-Australian Telescope images of M83 ESO/VLT images of M83 NRAO/VLA radio images of M83 Chandra X-ray Observatory images of M83 GALEX images of M83 in the ultraviolet light More images of M83 Amateur images of M83

• SIMBAD Data of M83
• NED Data of M83
• Publications on M83 (NASA ADS)
• Observing Reports for M83 (IAAC Netastrocatalog)
• NGC Online data for M83
  

Nebulosa tra le stelle Mi Scorpii e Eta Lupi

Coordinate del Cassini: Declinazione 39° Sud circa. Ascensione Retta 242° circa

Coordinate Perseus: Declinazione 39° Sud circa. Ascensione Retta 242°  = 16h 08'circa

Si tratta dell'ammasso aperto NGC 6124 di Mv 5,8 scoperto da Lacaille tra il 1751 e il 1752

Right Ascension	16 : 25.6 (h:m)
Declination	-40 : 40 (deg:m)
Distance	18.6 (kly)
Visual Brightness	5.8: (mag)
Apparent Dimension	29 (arc min)

Discovered by Lacaille in 1751-52.

The southern open cluster NGC 6124 was discovered by Abbe Lacaille during his 1751-1752 journey to South Africa.

The image in this page was obtained by Till Credner and Sven Kohle. It was cropped from a larger image, which they had obtained within their Constellations Triangulum Australe, Norma, Ara photography, which also covers parts of Scorpius. The image shown here is a magnification showing the region around open cluster NGC 6124. The original image, covering a celestial area of 27x39 deg in size, was obtained by Sven Kohle on June 11, 1994, 2:23 LT, from Cerro Tololo, Chile, using a 50mm f/2.8 photo lens. It is a 30 min exposure on Scotchchrome 400 film. More images from Till Credner and Sven Kohle

In the Astronomical League's Southern Sky Binocular Club list. Caldwell 75 in Patrick Moore's List.

• Jean-Claude Mermilliod's WEBDA cluster page for NGC 6124
• SIMBAD Data of NGC 6124
• Publications on NGC 6124 (NASA ADS)
• Observing Reports for NGC 6124 (IAAC Netastrocatalog)
• NGC Online data for NGC 6124
  

Nebulosa tra le stelle Lambda Scorpii (Shaula) e Epsilon Sagittarii (Kaus Australis)

Coordinate del Cassini: Declinazione 34° Sud circa. Ascensione Retta 263° circa

Coordinate Perseus: Declinazione 34° Sud circa. Ascensione Retta 263°  = 17h 32'circa

Si tratta dell'ammasso aperto NGC 6475 di Mv 3,3.  Già elencato nel catalogo di Tolomeo fu osservato da Hodierna nel 1654. E' presente nel catalogo di Messier come  M7

NGC 6475 Messier 7

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Open Cluster M7 (NGC 6475), type 'e', in Scorpius

The Scorpion's Tail, Ptolemy's Cluster

Right Ascension	17 : 53.9 (h:m)
Declination	-34 : 49 (deg:m)
Distance	0.8 (kly)
Visual Brightness	3.3 (mag)
Apparent Dimension	80.0 (arc min)

Known to Ptolemy 130 AD.

Messier 7 (M7, NGC 6475) is a large and brilliant group, easily detected with the naked eye. As Burnham describes it, "the cluster is seen projected on a background of numerous faint and distant Milky Way stars."

This splendid cluster was known to Ptolemy, who mentioned it about 130 AD and described it as the "nebula following the sting of Scorpius." The description may also include M6, but this is uncertain. Because of this presumable discovery, the present author [hf] has proposed the name "Ptolemy's Cluster" for M7 some years ago, a proposition which has found some acceptance meanwhile.

M7 was observed by Hodierna before 1654, who counted 30 stars. Edmond Halley listed it as No. 29 in his catalog of southern stars of 1678, and Nicholas Louis de Lacaille added it to his catalog of southern objects as Lac II.14. Charles Messier included it as No. 7 in his catalog on May 23, 1764.

M7 consists of about 80 stars brighter mag 10 in a field of about 1.3 degrees apparent diameter which at its distance of perhaps 800 light years corresponds to a linear extension of 18 or 20 light years. It was classified as of Trumpler type I,3,m or I,3,r. This group is approaching us at 14 km/sec. The brightest star is a yellow giant (spectral type gG8, mag 5.6), the hottest main sequence star is of spectral type B6 (mag 5.89). M7's age was estimated at 220 million years, both according to the Sky Catalog 2000 and the new calculation of the Geneva Group of G. Meynet. Recent work suggests a slightly larger distance of 1000 light-years, which would increase the size to 25 light-years but would not affect the age.

Ake Wallenquist found that this is one of the clusters with the highest degree of concentration toward the center. Modern sources agree on M7's integrated apparent visual brightness at magnitude 3.3, while older estimates, mostly from northern observers, had this southern cluster significantly underestimated at mag 4.1 to 5.0.

Historical Observations and Descriptions of M7 More images of M7 Amateur images of M7 More images of M6 and M7

• WEBDA cluster page for M7
• SIMBAD Data of M7
• NED Data of M7
• Publications on M7 (NASA ADS)
• Observing Reports for M7 (IAAC Netastrocatalog)
• NGC Online data for M7
  

Nebulosa presso la stella Beta Arae

Coordinate del Cassini: Declinazione 53° Sud circa. Ascensione Retta 261,5° circa

Coordinate Perseus: Declinazione 53° Sud circa. Ascensione Retta 261,5°  = 17h 26'circa

Si tratta dell'ammasso globulare NGC 6397 di Mv 5,9 scoperto da Lacaille tra il 1751 e il 1752

Right Ascension	17 : 40.7 (h:m)
Declination	-53 : 40 (deg:m)
Distance	7.2 (kly)
Visual Brightness	5.9 (mag)
Apparent Dimension	26.0 (arc min)

Discovered by Lacaille in 1751-52.

This conspicuous globular is one of the two nearest to us (the other one is M4); currently it seems that M4 is a bit closer: M4 is at about 6,800 and NGC 6397 at 7,200 light years, but the uncertainty is large enough that the sequence may change..

NGC 6397 is one of the at least 20 globulars of our Milky Way Galaxy which have undergone a core collapse, i.e. its core has contracted to a very dense stellar agglomeration; this is the nearest such globular.

The image in this page was obtained by Till Credner and Sven Kohle. It is a magnification of a small region of a much larger (wider-field, 27x39 deg) photograph obtained within their Constellations Triangulum Australe, Norma, Ara photography, which was obtained by Sven Kohle on June 11, 1994, 02:23 LT from Cerro Tololo, Chile with a 50mm f/2.8 photo lens, exposed 30 min on Scotchchrome 400 film. More images from Till Credner and Sven Kohle

In John Caldwell's observing list. In the Astronomical League's Southern Sky Binocular Club list. Caldwell 86 in Patrick Moore's list.

The HST has investigated globular cluster NGC 6397 for faint red dwarf stars, in order to check the abundance of these "Dark Matter" candidates. Look at the first and second HST press release on this thread.

• Marco Castellani's data for NGC 6397
• SIMBAD Data of NGC 6397
• Publications on NGC 6397 (NASA ADS)
• Observing Reports for NGC 6397 (IAAC Netastrocatalog)
• NGC Online data for NGC 6397
  

Nebulosa presso  la stella Alfa Arae

Coordinate del Cassini: Declinazione 47° Sud circa. Ascensione Retta 262° circa

Coordinate Perseus: Declinazione 47° Sud circa. Ascensione Retta 262°  = 17h 28'circa

Non può che essere l'Ammasso Aperto IC 4651 di Mv 6,9  che Cassini indica con una notevole imprecisione ribaltandone la posizione rispetto  alla stella Alfa dell'Altare.

IC 4651

per cortesia di

Dreyer's description: Cl, pC

Cross Identifications: Bailey .

Right Ascension:	17 : 24.7 (hours : minutes)
Declination:	-49 : 57 (degrees : minutes)
Apparent Magnitude:	6.9
Apparent Diameter:	12. (arc minutes)

NGC Home IC 4650 | IC 4652

Digital Sky Survey image Revised NGC/IC data NGC/IC data SIMBAD data HST Archive images NED data Publications and References (ADS) Observing Reports (IAAC Netastrocatalog)

Nebulosa posta al centro del triangolo formato dalle tre stelle Alfa Tucanae, Alfa Indi, Alfa Gruis (Alnair)

Coordinate del Cassini: Declinazione 56° Sud circa. Ascensione Retta 319,5° circa

Coordinate Perseus: Declinazione 56° Sud circa. Ascensione Retta 319,5°  = 21h 18'circa

All'esterno del tracciato della Via Lattea nel triangolo composto dalle stelle indicate appare un unico oggetto non stellare e visibile solo tramite uno strumento ottico : la Galassia NGC 7090 di Mv 10,7. Gli oggetti indicati da Cassini sono tutti tratti da osservazioni di Lacaille, in questa zona l'astronomo francese indica un asterismo formato da tre piccole stelline molto vicine di magnitudine 8.4, 8.2, 9.1 classificato come Lac III 14 che potrebbe coincidere con l'oggetto in questione. Confronta di Lacaille list of southern nebulous objects.

NGC 7090

per cortesia di

Dreyer's description: pB, pL, vmE 127deg , g, pslbM

Cross Identifications: GC 4679, h 3872. .

Right Ascension:	21 : 36.5 (hours : minutes)
Declination:	-54 : 33 (degrees : minutes)
Apparent Magnitude:	11. p
Apparent Diameter:	7.1 (arc minutes)

NGC Home NGC 7089 | NGC 7091

Digital Sky Survey image Revised NGC/IC data NGC/IC data SIMBAD data HST Archive images NED data Publications and References (ADS) Observing Reports (IAAC Netastrocatalog)

Nebulosa presso la Piccola Nube di Magellano

Coordinate del Cassini: Declinazione 74° Sud circa. Ascensione Retta 4,5° circa

Coordinate Perseus: Declinazione 74° Sud circa. Ascensione Retta 4,5°  = 0h 18'circa

Si tratta dell'ammasso globulare NGC 104 di Mv 3,83 scoperto da Lacaille  il 14 settembre 1751.

Right Ascension	00 : 24.1 (h:m)
Declination	-72 : 05 (deg:m)
Distance	13.4 (kly)
Visual Brightness	4.03 (mag)
Apparent Dimension	30.9 (arc min)

Discovered by Abbe Nicholas Louis de Lacaille on September 14, 1751.

NGC 104, better known as 47 Tucanae, is the second largest and second brightest globular cluster in the skies, outshone only by another southern globular, Omega Centauri (NGC 5139).

As its name "47 Tucanae" indicates, this object was first cataloged as a star and numbered the 47th in Tucana. Although a conspicuous naked-eye object, it is situated so much south at its declination of -72 deg, that it was not discovered as a deepsky object before 1751, when Abbe Lacaille cataloged it in his list of southern nebulous objects. Next to observe and catalog it were James Dunlop in 1826, and John Herschel in 1834.

The stars of 47 Tucanae are spread over a volume nearly 120 light years across. At their distance of 13,400 light years, they still cover an area of the sky of about the same apparent diameter as the full moon, about 30 minutes of arc. Globular cluster 47 Tucanae is approaching us at roughly 19 km/s.

The image in this page was obtained by David Malin with the 3.9-meter Anglo-Australian Telescope. This image is copyrighted and may be used for private purpose only. For any other kind of use, including internet mirroring and storing on CD-ROM, please contact the Photo Permissions Department (photo at aaoepp.aao.gov.au) of the Anglo Australian Observatory. More information on this image (David Malin); wider field

The Hubble Space Telescope has been used to investigate globular cluster 47 Tucanae:

• Image before and after COSTAR refurbishment mission [caption]

  The Chandra X-ray Observatory satellite has observed NGC 104 in X-rays:

• Chandra Reveals Nest of Tight Binaries in Dense Cluster 47 Tucanae

  The European Southern Observatory (ESO) has used its VLT to observe 47 Tucanae:

• Press Photo/Release ESO 20/06 (June 8, 2006)
• Photo Release ESO 20/06

  In John Caldwell's observing list. In the Astronomical League's Southern Sky Binocular Club list. Caldwell 106 in Patrick Moore's list.

   

• Marco Castellani's data for NGC 104
• SIMBAD Data of NGC 104
• Publications on NGC 104 (NASA ADS)
• Observing Reports for NGC 104 (IAAC Netastrocatalog)
• NGC Online data for NGC 104
  

Costruisci i

Globi di

Giovanni Maria Cassini

Cassini Globes (Christmas Balls).pdf

per cortesia di

Giuseppe (Pino) Civitarese

www.paperpino.net

www.atlascoelestis.com

di

FELICE STOPPA