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Dark nebulae in the winter skies

Introduction

Dark nebulae are galactic nebulae, that are not shining themselves or reflecting the light of stars, but appear as dark regions within the brighter stellar background. Only the dark clouds of highest density within the bright regions of the milky way are popular objects that can be seen even in binoculars, e.g. Barnard's "E" in the constellation eagle or the dark clouds within the brightest parts of the milky way in the constellations scorpion and archer (sagittarius). Many other dark nebulae are located in less dense regions of the sky or more transparent. Due to their week contrast the observation of those nebulae is limited to photography and to not light polluted sky. Therefore the most dark nebulae belong to the unknown, rarely observed deep sky objects. Important work for their investigation bas been done in the beginning of 20th century by E. E. Barnard. His astronomical work was dedicated to the photography of the sky, especially of regions of the milky way using lenses of small focal length, resulting in a wide angle of view. Analyzing the photographic plates, he discovered many dark nebulae, established a catalogue and investigated their nature. His catalogue of dark nebulae collects more than 300 entries - popular ones like the horse head nebula B33 or small objects of weak contrast.

Barnard Dark Objects in the winter skies

This collection of photographs aims to be a documentation of the 66 objects if the Barnard catalogue in the winter constellations using todays techniques. The photographs were taken using a digital single lens reflex camera (Nikon D50) and a tele lens (ED-Nikkor 2,8/180 at f/4) and 8 min exposure time for each shot. The conditions in the tirolean alps in austria were good (zodiacal light could be seen even in the late evening) but not unusual. For every image 2 to 3 single shots were averaged to reduce the noise. The contrast was drastically enhanced to make the dark nebulae visible even on usual computer monitors. Due to this procedure enhancement of blurring, distortion and inequalities in the background cound not be avoided. During the next years it is planned not only to extend this collection to the Barnard Dark Objects in the summer skies, but also to add high-quality photographs of selected, interesting dark nebulae.

Hopefully, this collection is not only able to anwer the question how the Barnard Dark Objects in the winter skies and their environment look like, but also may assist other observers that are interested in dark nebulae. The positions of the Barnard Dark Objects in star charts, tables and astronomical software should be carefully checked as they are sometimes systematically wrong. For this collection the positions from E. E. Barnards catalogue were transformed to the equinox J2000.0. The correct assignment of the objects on the photographs was manually checked. Except on B15-B17, that probably describe a single dark nebula, all Barnard Dark Objects in the winter constellations could be found and identified on the images. The labels were usually marked above the objekt on the photographs, in cases of large nebulae the labels are within their area. Dark nebulae from the LDN catalogue (Lynd's Dark Nebulae) were not listed and labelled (to keep the images clear) except on one prominent object in the field B12. The nebulae of the LDN catalogue are part of e.g. the astronomical software GUIDE 8.0.

Index pages:

• Index by field
• Index by object

Webpages of interest:

• A Photographic Atlas of Selected Regions of The Milky Way
• E. E. Barnard's Catalog of Dark Nebulae
• Lynd's Catalogue of Dark Nebulae