Object of the Season Archive

Jenni Kay and Wolfgang Steinicke

With this issue (DSO 138) we start a new series called “Object of the Season”.  The reader is requested to turn his/her telescope to selected prominent objects.  But observing is one thing, sending us the results is the essential.  This can be a textual description, a simple sketch (or even a fine drawing), or a photo (analogue, digital) – or any mix of these.  Ore work is to collect and publish your contributions, accompanied by information on the physical and historical background of the object.  The announcement (see this issue)  will only be a short appetizer, including the position and main data, needed for your observation.

To feature both hemispheres, we actually select two objects.  While my task will be managing the northern target, Jenni Kay is responsible for the southern.  The criteria are quite simple:  the object must be visible during the next quarter and should be observable in small telescopes.  Among the many possible targets we concentrate on those, which are interesting due to their appearance, type, nature, or history.  Finding the object should only require a standard sky atlas or common software.  Although easily visible, the object should bear features for a wide range of apertures, so every observer gets his won challenge.  Galactic and planetary nebulae, galaxies or clusters are good examples.  Less interesting might be quasars, although physically fascinating, their only feature is brightness.

For selecting a northern object there is a source, that fits best to our society: Webb’s “Celestial Objects for Common Telescopes”!  The idea for the southern sky is to use the catalogues of Bennett, Dunlop and various others.  With time the column “Objects of the season” will generate a useful collection of fine nebulae and clusters.

Your contribution (textual description, sketch or photo)  should include the main facts of your observation: location (elevation) , date/time size/type of telescope (focal length, aperture), eye-piece (magnification, filter), camera and exposure time (if used), sky condition (e.g. faintest star) and any other useful information.

First northern “Object of the Season” (Summer): The Planetary Nebula NGC 7027 in Cygnus Updated

The new column seems to be a success. The feedback is very positive – looks like, that many have waited for such a feature in DSO. I got 11 observations – quite a good number in view of this tiny object! Remember, that it was a natural choice, being discovered – at least independently – by the Rev. Thomas William Webb. The full story will be told in DSO 139, followed by some astrophysical facts, and your observations – fascinating to read!

As an example, the drawing illustrates Martin Lewis’ observation made near Llanafan, mid-Wales, UK (elevation ~500 m). He uses a 250 mm Newtonian, f/5.8, 368x (8 mm Super Wide Plössl and 2x Barlow), no filters. Faintest visual star was 6.0 mag, object altitude >70°.

Sketch courtesy of Martin Lewis

Northern Object of the Season (Autumn): The edge-on galaxy NGC 891 in Andromeda New

Our autumn object is NGC 891, ranking as one of the finest edge-on galaxies in the northern sky (see image). Located in Andromeda, 3° east of Almach (γ And), it is one of Caroline Herschel’s few objects. She found it on Aug. 27, 1783 with her 4.2" Newtonian comet seeker and was later catalogued by William Herschel as V 19.

At a visual magnitude of 10.1 mag this Sb galaxy is quite large (11.7' x 1.6'), resulting in a fairly low surface brightness of 13.1 mag/arcmin². Under best conditions it can be seen as a small elongated patch in a 4" telescope, but its striking feature, the dark absorption band, bisecting the galaxy, needs at least 8". NGC 891 is an object for a wide range of apertures. In large Dobsonians it shows fascinating details, like the dark “chimneys”. But don’t search for any globular clusters – there are non known.

Basic data:

Position (2000.0)                    02 22 33.0 +42 20 50

Type                                     Sb

Visual magnitude                   10.1 mag

Visual surface brightness        13.1 mag/arcmin²

Size                                      11.7' x 1.6' (PA 22°)

Other designations                 UGC 1831, MCG 7-5-46

Uranometria                           62 (old), 43 (new)

Please send your observations – which will be presented in DSO 140 – to:

Wolfgang Steinicke

Gottenheimerstr. 18

D-79224 Umkirch, Germany

steinicke-zehnle@t-online.de

Credits: X-ray (NASA/CXC/M. Karovska et al.); Radio 21-cm image (NRAO/VLA/J.Van Gorkom/Schminovich et al.), Radio continuum image (NRAO/VLA/J.Condon et al.); Optical (Digitized Sky Survey U.K. Schmidt Image/STScI)

Jenni Kay

NGC 5128, commonly known as Centaurus A. is a must see galaxy for any southern observer (Fig. 2 & 3).  It can be picked out easily through a 9x50mm finderscope as a bright, small, hazy spot and with ever increasing telescope aperture there is so much ore detail to be revealed.  A view through the 30-inch shows structure as fine as any picture I have ever seen of it.  James Dunlop first discovered the galaxy in 1826 with a 9-inch reflecting telescope from Paramatta, New South Wales, Australia. Centaurus A is also a powerful radio source with radio jets shooting out from the centre of it. It is also very energetic in X-rays, Gamma rays and infrared.  Some 100 million years ago it devoured a small spiral galaxy, causing a burst of star formation which is still going on.  This is no docile galaxy!  So point you r telescopes towards this galaxy, and feast on the beast, and then please let me know what you see.  How many stars can you see superimposed over the galaxy?  Can you detect anything within the dark rift?

Please can you send your observations before September 30^th 2005 to me at …..

Jenni Kay

PO Box 74,

Lobethal, SA. 5241, Australia.

jenni@esc.net.au