Mississauga Astronomical Society

56th Meeting

Speaker’s Night

Day:                February 10, 2006

Speaker:     Paul Gray

SuitSat Video

Randy Attwood showed the NASA video of the SuitSat launch, the ham radio in a Russian spacesuit.

Dark Nebulae: Observations from the Dark Side

Paul Gray from the Moncton Centre of the RASC writes the Dark Nebula section in the Observers Handbook and spoke about these objects.   Originally these were thought to be holes in space. E.E.Barnard purchased a 5” telescope in 1876 and began to search for comets in 1885, discovering 8.  In 1892 he discovered Jupiter’s moon Amalthea, and in 1916 discovered the fast proper motion of Barnard’s star.  He created and published a photographic atlas of selected regions of the Milky Way, cataloging dark regions.  The atlas is filled with detailed descriptions of the dark objects seen in the photographic plates.  After study of these, Barnard came to the realization that these were not holes in space but obscuring dust.  We now know that some dark nebulae are areas of voids though most are obscuring regions.  

In 1999, a copy of Barnard’s atlas found its way to Doug Pitcairn.  He selected dark nebulae to see which could be observed and made a list of about a dozen objects.  In 2000, Paul restarted the project and published a list of about 30 observable Barnard objects in the Observer’s Handbook of the RASC.  He described a number of these including some which are naked eye objects.  In some cases, subtle contrast changes need to be noticed. A dark sky with above average transparency, dark adaptation, observing the object when on the meridian, use of the proper field of view, utilization of a LPR filter when the object is on an emission nebula are all necessary for observing these objects.  Uranometria 2000.0 used to be the best atlas but it doesn’t list all the Barnard objects. As a result photographs are best for finding the objects.

Paul showed examples from Barnard’s atlas.  After seeing B132, 133 in Aquila, one can starhop to nearby B334, 335, 337.  In the Scutum star cloud B141, 137, 138 139 make a binocular object described by Barnard as a Lizard.  In the North America nebula he described B352, 353 and the difficult 355 which is equivalent to the winter Horsehead nebula.  He spoke about  the Lagoon nebula and its dark objects.  By going to the original sources, Paul was able to ascertain that B88 and the “dark comet” listed in Burnham’s Celestial Handbook are two separate objects, and they are listed as such in the RASC Observer’s Handbook.  Finally, Paul described the objects near the head of Orion including B223 (also known as vdB38) which is the only bright nebula in the Barnard catalogue.  Paul is on a project to visually observe all the Barnard objects and he encouraged others to observe them. 

Abbey Ridge Observatory Supernova Search

In the second part of his presentation, Paul Gray spoke about the search for supernovae that he and Dave Lane are conducting. The search program and Abbey Ridge Observatory were described by Dave on October 29, 2004 at a MAS meeting – please see the writeup of that meeting.

Paul described a supernova and went over the rationale for searching many galaxies in the northern sky in an automated manner.  The rewards for success are the thrill of discovery, feeling of accomplishment and prestige. The search program began in 1993/94 and ended after the discovery of SN 1995F. It re-started in 2003. 

Paul described the misses of SN 2004ET in NGC 6946 which was imaged 6 days prior to discovery and SN 2004FU in NGC 6949 imaged just days after discovery.  More disappointing were3 other supernovae (SN 2006N, 2005EJ and 2004ED) which were either not seen in images or missed within days of discovery by another team.  However, there were successes with SN2005b and 2005EA.  

There are rewards to making these discoveries.  Paul and Dave’s names were published in the IAU Circulars.  Observing time was scheduled for the 3 ½ meter Lick and 5 meter Palomar telescopes to image the supernovae.  They won the Ken Chilton Prize in 1995 and the Chant Medal in 1996, and the “Bring Home the Bacon Award” presented at Starfest 2005.   To date, Paul and Dave have 25,278 galaxy images with 2 supernova discoveries and 3 pre-discoveries, with 6 misses of only a few days.    

Submitted by Chris Malicki, Secretary  Chris Malicki, Secretary                               back to M.A.S. meeting reports page
Mississauga Astronomical Society