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BAA Gallery Picture of the Week

DWB 111 - The "Propellor Nebula"


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About this observation
Graham Roberts
Time of observation
07/09/2019 - 22:30
DWB 111
Observing location
Redhill, Surrey, UK
William Optics GT81 + Focal Reducer FL 382mm f4.72
ZWO1600MM camera
22 x 300 sec Ha, 8 x 300 sec OIII & SII

In a quest to find and image new targets Graham's curiosity was drawn towards a more obscure catalogue of HII emission nebula, in particular DWB 111, AKA Simeis 57 or The Propellor Nebula.  The object was first catalogued in the early 1950s by the Crimean Astronomical Observatory at Simeiz, Ukraine as number 57 of a total of 306 HII regions!  Then in 1969 H.R. Dickel, H. Wendker and J. H. Bieritz (DWB) developed a catalogue of 193 optically visible HII objects in the Cygnus-X region of the Cygnus constellation, which included DWB 111.  Strictly speaking the Propellor consists of DWB 111 & 119 with other close-by features DWB 107,108, 118, 125 & 126.

Whatever the nomenclature, locating DWB 111 was difficult but Graham eventually found and installed the necessary data.  The target is located between Vega and Deneb, which at this time of the year tracks northwest directly above his observatory, meaning imaging is confined to just about 2 hours due to local obstructions.  Graham concentrated on imaging the Ha wavelength, with only a few SII and OIII subs, which are both weak in nature.  However, the results speak for themselves and Graham has presented three separate versions for consideration.  I chose the SHO version, but the others show a wealth of additional information and they can be seen on his website at

Numerous filament-like threads produce fascinating structures which run throughout the nebulosity, making for a truly exciting image. Additional integration time is planned for the future.

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