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Popular Astronomy

March 2016

Four section members sent in sketches and images of deep sky objects during March, 16 reports in total:  11 images and 5 sketches.

Dale Holt drew 2 galaxies, a galaxy pair and 2 planetary nebulae.  From the left below and in a clockwise direction are M104 (the "sombrero" galaxy) in the constellation of Virgo, NGC4027 (also known as Arp 22), NGC4361, and NGC4782 & 3, all in Corvus. M104 owes its popular name to the dark lane of dust and prominent central bulge.  NGC4027 owes its place in Arp's catalogue of peculiar galaxies to the fact that one spiral arm has been drawn out in an encounter with a galactic neighbour.  Planetary nebula NGC4361 is unusual in that it has four lobes of ejected material, leading to speculation that there may be two stars inside, each producing a bipolar jet. 

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    Dale's fifth sketch (below right) is of a better known planetary nebula, NGC2392 or the "eskimo" nebula, in the  constellation of Gemini.                                  

                                                                                

This magnitude 10 object has a high surface brightness and can be readily seen in small telescopes, but is quite small at about 50 arcseconds angular diameter, so a bigger telescope is needed to see the detail present.

                                                                                   

For these sketches Dale used a 505mm f3.5 Newtonian telescope, with a Watec 120N+ cooled video camera in place of an eyepiece.

                                                                                                                                                                     

                                                                                  

                                                                                   

Mark Beveridge imaged 6 galaxies.  Below left is M64, the "black eye" galaxy, which has a very distinctive appearance due to a large band of light absorbing dust. It lies in the constellation of Coma Berenices.  Below right is NGC3938, a face-on spiral in Ursa Major.                                                  

                                                                                   
                                                                                        Mark's next four images are, from below left, clockwise:  NGC4228, an irregular galaxy in Canes Venatici containing large star forming regions;  NGC5033 also in Canes Venatici, which has an active nucleus, NGC3972 in Ursa Major;  and also in Ursa Major NGC2841, a giant spiral galaxy noted for large numbers of young, blue stars but few HII regions.                                                                             

      

David Davies sent in this image (right) of open cluster M45, the pleiades, in the constellation of Taurus.  He captured 100 minutes each of red, blue and green in 5 minutes subframes, using a Skywatcher ED80 refractor (working at f5.3) plus a QSI583 mono camera and red, green, and blue filters.

                                                                               

M45 is one of the nearest open clusters to the Earth, and is probably the easiest to identify without any optical aid.  The luminous blue stars in the cluster illuminate the dust clouds around them, through which the cluster is passing.  

                                                                                                                                                                   

Steve Norrie sent in four images, all of galaxies.  From below left, clockwise, the first three are in the constellation of Ursa major:   M108, M101 and M81 (also M82).  The fourth image is of M106 is Canes Venatici.  M108 is an almost edge-on barred spiral galaxy.  M101 is better known as the "pinwheel" galaxy;  it is face -on to us so has a fairly low surface brightness.  M81 is also known as Bode's galaxy, and with M82 38 arcminutes away may be seen in the same field of view in 10x50 binoculars.  M106 has an active nucleus and is classed as a Seyfert type II galaxy.

                                                                                                                                                                          

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