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Comet ISON - Back From The Brink! PDF Print E-mail
Written by Dave Grennan   
Friday, 29 November 2013 21:29

Reports are still flooding in surrounding the fate of Comet ISON.  The icy wanderer made its closest approach to the Sun on November 28th at 18:35UT.  As it passed, it endured temperatures exceeding 2000C and was literally being torn apart by the Sun's gravity.  As astronomers worldwide waited with baited breath, anticipation turned to heartache as only a faint streak was seen emerging. It seemed very likely that the head of the comet which is about the size of a small city had disintegrated completely and that ISON's 6 billion year journey to the inner solar system was over in the blink of an eye.

However comets are nothing if not surprising beasts.  Suddenly heart began to flutter again as the faint streak turned into a coherent point and began to brighten.  As the hours passed views from the spacebased Solar and Heliospheric Observatory (SOHO) made it abundantly clear that at least some part of comet ison had survived. Whether the comet has survived mostly intact or only a fraction remains is still being hotly debated.  My view is that Comet ISON has indeed shattered into many fragments.  I base this view on some subtle evidence.  The animation below is from SOHO's LASCO C3 view.  What we see is a comet which does not have a very sharp head.  This is partly due to the rotation of the axis of the dust tail but I do not beleive entirely so.  The comet almost looks slightly "out of focus".  This leads me to suspect that the comet is now not just one source but multiple sources.


Also consider the following enhanced image (also from LASCO C3)  highlighted are points which just might be multiple sublimation points

So what does this mean for the prospects of Comet ISON putting on a good show in early December?  A fragmented comet has more surface area exposed to the elements which could result in higher sublimation rates and thus a brighter apparition.  However that is highly dependent on just how much material remains in its icy and dusty core.  The simple answer is that nobody knows.  We will simply have to wait and see what happens in the next few days.  We astronomers are an optimistic bunch.  So lets assume that comet ISON puts on a half decent show and will be visible to the naked eye in early December.  The chart below shows where to look for it.  It's plotted for about 20 minutes before sunrise (just before 8:00am)  As the days pass the comet rises higher into the morning sky.  Also keep note that as it rises earlier each subsequent morning, you will be able to spot it earlier in a darker sky.  Binoculars will always be a help.  However care is needed to ensure that you DO NOT use any optical aid when the Sun is above the horizon.  In fact dont even stare in that direction evenb without optical aid.  You have been warned.  Please send me details about what you see and I'll do my best to compile your observations/drawings/photos on this page.  If you have kids why not get them to draw the scene.

Click for larger view

The above finder may be used on your own website/publication with appropriate credit.  Please contact me for an unmarked version.



Last Updated on Friday, 29 November 2013 22:02
New Telescope for Raheny PDF Print E-mail
Written by Dave Grennan   
Friday, 12 July 2013 20:20

Since last December, a new telescope for Raheny Observatory has been under construction.  Much of that time was taken grinding and polishing the main mirror.  A 14" f/3.85 precision optic which will deliver crisp a clear wide views of the night sky.  Much of the survey work done at Raheny involves covering as much sky as possible in a clear sky window.  This telescope, when complete will enable me to cover significantly more in an evenings work and hopefully increase the number of discoveries made by me ar Raheny.  A major milestone was reached this week when the main mirror returned to Raheny after making a visit to a specialist coating plant to have it's reflective coating deposited.

The following is a detailed article discussing the grinding and polishing and figuring of the mirror.



Last Updated on Friday, 12 July 2013 20:40
Jupiter image from Balbriggan. PDF Print E-mail
Written by Dave Grennan   
Sunday, 16 December 2012 21:31

Carl O'Beirnes sent this wonderful image of Jupiter taken Friday 14th December.

(Click for larger image)

Carl Says - "The processing on this image was done differently. First of all each image was loaded into autostakkert and processed. All the sharping was done in Registax v6. Once all the images are sharpened each set of Reds Greens and Blues where analysed and de-rotated in Winjupos.  Final processing was done in Adobe Photoshop.

The images where captured using a C14 OTA on an AP1200 mount. Lumenera Skynyx 2.0m CCD camera, Astronomik RGB filters and a 2X Barlow."


All in all I think this is a really exceptional image.  Note the swan like feature in the centre of the image.

Last Updated on Sunday, 16 December 2012 21:59
Scopes and Space PDF Print E-mail
Written by Dave Grennan   
Monday, 10 June 2013 21:19

Webtreatz.com are delighted to recommend Ireland's newest astronomy superstore.  Scopes and Space are located in swords as a brand new venture.  They stock a huge amount of quality astronomical equipment.  Check out their website and drool over the largest range of telescopes and accessories available to Irish and European astronomers.  The founders are regular contributors here at webtreatz.com and so I am happy to recommend the guys for everything you may need for your astronomy pursuits.

Memories of Sir Patrick Moore. PDF Print E-mail
Written by Dave Grennan   
Monday, 10 December 2012 22:16

We learned with the deepest sadness of the passing of our friend and inspiration, Sir Patrick Moore CBE.   No doubt many will testify that Patrick inspired so many people's interest in astronomy.  In particular his show "The Sky at Night" became an institution not only in Britain but all over the world. On many occassions Patrick welcomed his Irish friends into his home.  His hospitality was as immense as his encyclopaedic knowledge of all things space related.  Patrick had a particular interest in the moon and his detailed maps were used by NASA during the Apollo preparations.

It is hard to imagine that this great man played piano with Albert Einstein, was close friends with the late Neil Armstrong and was always up to speed with the latest space missions.  He literally inspired generations and for that we should be forever grateful.

Sir Isaac Newton was of course long passed before Patrick was even born but when he said "If I have seen farther, it is because I stood on the shoulders of giants", he must have been invisaging a man such as Patrick.  For Patrick was just that.  One of the very few true giants of astronomy, who will be sorely missed.


On one of our visits to his home in Selsey in 2008, we made a short documentary.  A kind of behind the scen's look at "The Sky at Night" and a tribute to the great man himself.

Rest in Peace Patrick from your friends in Ireland.

Click here to watch the video tribute.

Last Updated on Sunday, 16 December 2012 21:51
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