Propeller nebulae-HOO-rgb<\/span> <\/span><\/p><\/h2><\/span> Commentaires sur l’objet photographi\u00e9<\/span><\/p><\/h1><\/span> Il aura fallu quasiment tout l’\u00e9t\u00e9, si on peut appeler cela un \u00e9t\u00e9 ! traitement classique en HOO-rvb avec 20% d’apport de RGB sur la couche HOO.<\/p>\n Donn\u00e9es techniques Object : Propeller nebuale Rouge 30 x 5′ \/ vert 30 x 5′ \/ bleu 30 x 5’<\/p>\n<\/div><\/div><\/div> The Propeller Nebula (Simeis 57 or DWB 111\/119) is an emission nebula within the giant molecular cloud of Cygnus X located about 4500-6000 (estimated) light years from Earth in Cygnus.\u00a0 It was first catalogued in the 1950s by astronomers working at Simeiz Observatory in Ukraine as the 57th object in their catalogue containing 306 HII regions.\u00a0 In 1969, astronomers H.R. Dickel, H. Wendker and J.H. Bieritz published a paper labeling the central part of the Propeller Nebula separately as DWB 111 (southern arm) and DWB 119 (northern arm) with the bright patch surrounding it as DWB 118.\u00a0 The DWB catalogue contains 109 emission nebulae related to the Cygnus X star forming region.\u00a0(credit:\u00a0 Gabor Toth Astrophotography and cosmicneighbors.net)<\/p>\n he entire complex was assigned Simeis 57 when it was discovered in the early 1950s by G.A Shajn and V.E. Hase at the Crimean Astrophysical Observatory at Simeis, Russia.\u00a0 Their results were published in the observatory’s\u00a0Bulletin of the Crimean Astrophysical Observatory<\/u>\u00a0(in Russian,\u00a0Izvestiya Krymskoi Astrofizicheskoi Observatorii<\/u>), although they did not become widely known outside of the Soviet Union at the time, probably due to the Cold War raging at the time.<\/p>\n Later, portions of Simeis 57 were assigned separate designations in various catalogs.\u00a0 The propeller’s southern blade is listed as DWB 111, after a\u00a01969 article<\/a>\u00a0detailing the Cygnus X region, written by H. R. Dickel, H. Wendker, and J.H. Bieritz that appeared in the journal\u00a0Astronomy & Astrophysics<\/u>\u00a0(A&A, vol. 1, p. 270 – 280).\u00a0 The same article listed the northern blade as DWB 119.\u00a0 Fainter sections were assigned other DWB numbers, although for our purposes here, we will concentrate on trying to see the propeller itself.\u00a0 That’s tough enough.\u00a0 (Sidebar: For a more up-to-date review of the physics behind Simeis 57, read\u00a0The peculiar nebula Simeis 57-I. Ionized gas and dust extinction<\/a>, also published in\u00a0Astronomy and Astrophysics<\/u>\u00a0[A&A vol. 398, p. 1063-1071].)<\/p>\n As with so many emission nebulae (or hydrogen-II regions, if you prefer), the Propeller Nebula is very difficult to see by eye alone.\u00a0 That’s because its primary emissions lie in the red portion of the visible spectrum, where our eyes are all but blind under dim light conditions.\u00a0 And they don’t come much dimmer than Simeis 57.<\/p>\n The blades of the propeller span about 20′, so in order to squeeze both into the same view, select an eyepiece with a real-field coverage of at least half a degree.\u00a0 A modern, ultra-wide design with an 80\u00b0-plus apparent field is better than, say, a more conventional Pl\u00f6ssl, since their wide apparent fields also produce a higher magnification for the given real field.\u00a0 That’s important consideration, since higher magnification will generate better image contrast.<\/p>\n To boost contrast further, experiment with various nebula filters.\u00a0 Not to plant any preconceived prejudices in your mind, but narrowband (UHC-type) and O-III filters seem to offer little positive effect on the Propeller.\u00a0 On the other hand, a Hydrogen-Beta (H\u03b2) filter, which rarely seems to help objects beyond the Horsehead Nebula, usually proves to be the top choice here.\u00a0 But again, try each filter in your cadre and see which produces the best results.<\/p>\n The Propeller is 5\u00b0 southwest of Deneb [Alpha (\u03b1) Cygni], and just to the west of a right triangle the 7th-magnitude stars SAO 49403, 49413, and 49418.\u00a0 While that triangle is obvious in the 8×50 finderscope attached to my 18-inch, the Propeller itself takes better skies than I can hope for from my suburban observatory.\u00a0 Under naked-eye limiting magnitude 6.5 skies, however, the 18-inch at 94x and with an H\u03b2 filter in place reveals a very soft glow after a concentrated search.<\/p>\n<\/div><\/div><\/div>![](\"http:\/\/outters.fr\/wp-content\/uploads\/2021\/09\/X_nebulae-HOO-rgb20-1.jpg\")
<\/a><\/span><\/div><\/div><\/div>Image HOO-RGB<\/h2><\/a><\/div><\/div><\/div>
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\n<\/span><\/p><\/h2><\/span>Donn\u00e9es techniques de prise de vue<\/h2><\/div>
\nDate images Du 29 juin\u00a0 au 7 aout 2021
\nOptics : Rcos 12.5″
\nMount : Paramount ME Num\u00e9ro 3
\nLocation : Sirene observatory
\nSeeing : fwhm :\u00a0 1.46 \u00e0 2.18 arc sec \/pixel
\nCcd : Apogee 16U
\nfilter wheel : Apogee
\nfilters : Astrodon
\nSIIHaOIII rvb
\nFocuser :TIM
\nGuiding : Atik 314L+
\nTemp. out : T\u00b0
\nTemp ccd : -25\u00b0
\nTotal exposure : 49 h
\ntout en binning 1×1
\nSII : 29 x 20′
\nOIII : 36\u00a0 x\u00a0 20′
\nHa : 54 x 20 ‘
\nRVB :\u00a0 37 x 5′ pour chaque filtre<\/p>\nDonn\u00e9es scientifiques<\/h2><\/div>