Annual Meeting of the Deep Sky Section, 2011 March 12

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Annual Meeting of the Deep Sky Section, 2011 March 12

held at Ashford Village Hall, Ashford Hill, Berkshire

Dr Stewart Moore, Director of the Deep Sky Section, welcomed the audience to the meeting and thanked Newbury Astronomical Society for hosting it. He especially thanked Ann Davies and David Boyd for arranging the refreshments. He explained that this year marked the thirtieth anniversary of the Section's foundation, in September 1981, and so this year's meeting would be a timely opportunity for several talks reviewing the changes seen over those three decades, but first he presented his Annual Review of the Section's work.

Annual Review

Dr Moore reported that 44 observers had submitted images to the Section since its previous meeting in March 2010. Three newsletters had been produced in that time, in May, September and January. For the first time, these had been circulated electronically as pdfs, making it possible to do better justice to the fine colour images that could be obtained with modern CCD cameras than was possible within the Section's printing budget. Black-and-white photocopies remained available on request to those members without internet access. Dr Moore added that he was always keen to receive contributions for these newsletters, and that he particularly welcomed images which were accompanied by notes about the equipment used or the story behind the observer's choice of target; this additional context could add considerably to the interest of the images.

Several observing projects had also been publicised to a wider audience by articles in the news section of the BAA Journal. Owen Brazell1 and Grant Privett2 had recently written articles about NGC 40 and Gyulbudaghian's nebula respectively, and the Director encouraged others to consider contributing similar articles.

Turning to describe the observations which Section members had made over the year, Dr Moore noted that the weather had been particularly unfavourable across the UK over the past few months. This was reflected by a lull in supernova discoveries by UK amateurs of late. Nonetheless, Ron Arbour had made one discovery in the past year, 2010hi in NGC 6621, discovered on September 1, bringing his tally to 24. Tom Boles had made nine discoveries over the year, most recently 2010js in UGC 4924, discovered on November 7, bringing his tally to 138.

The Section's project to observe Abell planetary nebulae had received a few new observations over the year, of Abells 12, 33, 36, 37, 39 and 50. Three of these images, those of Abells 33, 36 and 37, represented the first amateur observations of these objects to be received by the Section; lying in the magnitude range 11.5–14, these objects presented considerable challenges. A couple of even more difficult planetary nebulae had also been observed by the Section's most dedicated observers. Both Grant Privett and Maurace Gavin had successfully captured images of the Necklace nebula, an object newly discovered3,4 in Sagitta in 2010 by the IPHAS survey5,6 . Privett had also captured an image of the Soap Bubble Nebula (PN G75.5+1.7), another relatively recent discovery, this time by American amateur astronomer Dave Jurasevich in 2008 July and lying in Cygnus. Details of all of these observations could be found in the Section's January newsletter. Within the past few weeks, Privett had turned his attention to faint local group galaxies, submitting images of Leo 2, Leo A and Sextans B.

Turning to variable nebulae, the Director opened with a pair of images of Hubble's variable nebula, taken by Nick James in 2010 March and Maurace Gavin in 2010 November, which showed clear changes to the structure of the nebula over those eight months. Hind's nebula presented a fainter, more challenging target, but Dale Holt and Maurace Gavin had submitted images. Few observations of McNeil's nebula had been received in recent years, since the initial flurry of interest which had followed its discovery in 2004; there was an ongoing need for the Section to monitor it, and negative observations would be as useful in this regard as positive detections.

Gyulbudaghian's nebula had been well observed over the course of the year. At the previous Section meeting in 2010 March, it had been reported faint at mag 16.5, but it had subsequently gone on to brighten rapidly, peaking at mag 15.8 in the early summer. It now seemed to have faded again. David Boyd had recorded systematic photometric measurements of both the nebula and the variable star PV Cephei, 11'' distant, thought to be the nebula's primary source of illumination. He had found that the nebula's lightcurve was a close match to that of PV Cephei, but shifted 32±4 days later. This shift could be explained if the physical separation of the star from the nebula was 32±4 lightdays, or 0.027±0.003 parsecs, which was consistent with other estimates of the nebula's distance and angular separation from PV Cephei. This work would be written up in full in a future issue of the BAA Journal.

Having reached the end of his Annual Review, the Director proceeded to deliver the next talk also, reviewing some of the changes in imaging technology seen over the 30-year history of the Section.




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