[BAA-ebulletin 00770] Comet C/2012 S1 (ISON)

[Rick]

[BAA-ebulletin 00770] Comet C/2012 S1 (ISON)
(c) 2013 British Astronomical Association    http://www.britastro.org/

This comet is now only 15 days from perihelion and it is currently 0.66 AU from the Sun. In recent days it has been seen to brighten as expected and it is now around magnitude 7. There has also been a noticeable increase in the level of activity within the tail. The rather bland and uniform dust tail has been supplemented by a number of straight gas streamers which are now relatively easy to image.

The main dust tail has broadened and is now around 1 degree long and today's observations show that the gas tail has undergone a disconnection event due to its interaction with the solar wind. This is clearly visible in images obtained by BAA observer Tony Angel:

http://britastro.org/baa/index.php?view=detail&id=1908&option=com_joomgallery&Itemid=200

The comet is currently a morning object low in the eastern dawn sky with a very short observing window before the onset of twilight. Despite the difficult conditions it would be very worthwhile to make an attempt to observe this object. We cannot reliably predict what will happen in the coming weeks since we have never before seen a comet with these characteristics pass so close to the sun. Only continued observations will help us to tell the final tale.

It is worth noting that due to the comet's brightness and tail length the most suitable imaging instruments are now the very popular (and fairly common) 80mm apochromatic refractors coupled to CCDs or DSLRs. This type of instrument tends to be portable so it can be taken to a site with a clear eastern horizon.

Drawings, images, written accounts and visual magnitude estimates are welcome and can be posted via email to cometobs at britastro.org. It would help greatly if you could conform to the file naming convention documented here:

http://www.ast.cam.ac.uk/~jds/cimgname.htm

Images of this comet taken by BAA observers and others up the present date can be seen on the BAA Comet Gallery:

http://britastro.org/baa/index.php?view=category&catid=74&option=com_joomgallery&Itemid=200

The increase in activity during the past week could be a sign that the comet may become a naked eye object at some point around perihelion or just after. Of course, at the time of perihelion the comet will not be observable using basic observing techniques due to its close proximity to the sun.

The best source of information about the comet during the next few weeks can be found at the NASA CIOC website:

http://www.isoncampaign.org/Present

There is another naked eye comet currently available in the night sky. This is C/2013 R1 (Lovejoy). This comet is best seen around midnight and onwards. It is presently in Leo and images of this comet taken by BAA observers can be found on the BAA Comet Gallery:

http://britastro.org/baa/index.php?view=category&catid=133&option=com_joomgallery&Itemid=200

Denis Buczynski
Secretary Comet Section
British Astronomical Association

[MarkS]

I reckon it was around 7.8 from my image on Saturday. 
Previous weekend was 10. 
So it's brightening quite rapidly.

[Mike]

I reckon it was around 7.8 from my image on Saturday. 
Previous weekend was 10. 
So it's brightening quite rapidly.

Great. Hopefully it should be naked eye visibility before too long.

[MarkS]

Trouble is, we're just about to lose it into the dawn skies until it re-emerges from its trip round sun. If it survives then surely it will be an naked eye object!  A very toasted comet.

[Rick]

[BAA-ebulletin 00771] Comet 2012 S1 (ISON)
(c) 2013 British Astronomical Association    http://www.britastro.org/

Comet 2012 S1 (ISON) has brightened dramatically by over two magnitudes and is now 5th magnitude or brighter.  It is not clear whether this brightening represents a terminal disruption or a rejeuvenation of the active areas. Only further observation will show which is the case.  On the one hand it may continue to show a well condensed inner coma, on the other hand the coma may steadily become more diffuse.  The brightness evolution is uncertain.

The inner coma region is particularly important, and imagers need to take many short exposures in order to avoid saturation of features.  These can be stacked to show detail both in the inner coma and the tail region as appropriate.  Many recent images are over-exposed in the inner coma region.

Comet 2013 R1 (Lovejoy) is nearing is likely peak brightness at around 5th magnitude.  Both comets are best seen just before dawn.  Unfortunately high cloud covers much of the UK (despite the weather forecast showing clear skies in the south) and this is likely to prevent observation.  Scotland looks better placed on Sunday morning, whilst clear skies may be more widespread on Tuesday morning.

Further information on the comet is on the Section web page at http://www.ast.cam.ac.uk/~jds

Jonathan Shanklin
Director, Comet Section

[Rick]

[BAA-ebulletin 00775] Comet 2012 S1 (ISON)
(c) 2013 British Astronomical Association    http://www.britastro.org/

It seems that the comet has survived its close encounter with the Sun, thus increasing the chances of there being something to see in the coming weeks. You will need to get up early as the comet is most likely to be seen between 06:30 and 07:00 low in the east-south-east over the next few days, most likely from December 3 onwards.  Tomorrow morning is probably too soon, but you never know, particularly if the comet is brighter than expected.  For the next week you will need a clear horizon as well as clear skies as the comet is very low down.  It gets higher in the sky, but will fade, though the tail may become more prominent.  The best views might come around 06:00 between December 7 and 14, and at the end of this period you might also see a few Geminid shooting stars.  By mid December it will be visible in the evening, and by Christmas it will be visible all night, though you may need binoculars to see it.   Sky & Telescope have some finder charts at http://www.skyandtelescope.com/observing/ataglance

There is another comet visible from the UK, 2013 R1 (Lovejoy), which may be seen in binoculars as a fuzzy patch, about half the size of the Moon, roughly 15 degrees west of the Plough near the top of Bootes.  It is at nearly the same altitude as the Plough at 18:00.  It continues to move west at two to three degrees per day.

Jonathan Shanklin
Director, Comet Section

[Rick]

[BAA-ebulletin 00776] Comet 2012 S1 (ISON)
(c) 2013 British Astronomical Association    http://www.britastro.org/

Sadly the comet appears not to have survived its ordeal after all.  It steadily faded and became more diffuse after its initial reappearance.  I've posted a movie showing its passage through the C3 field on the Section web page. Something might be visible as the remnant moves into darker skies, but this is likely to require deep imaging.

To compensate, 2013 R1 (Lovejoy) is quite a nice object, with the tail becoming more prominent.  This is visible soon after dark, in Bootes. Binoculars will help to find it, but if you have clear dark skies you may see it with the naked eye.  A better view will be had in the early morning when the comet is higher in the sky.

See http://www.ast.cam.ac.uk/~jds for updates on cometary activity, and links to other useful information such as the Computing Section finder charts.

Jonathan Shanklin
Director, Comet Section

[Rick]

Today's EPOD shows Comet Lovejoy