13 April 2015 – First South African Comet Discovery in 35 Years
In the early hours of the 7th April, an un-manned robotic telescope, MASTER-SAAO, situated near Sutherland in the Karoo, discovered a new comet. This is the first comet to be discovered in South Africa since 1978.The Russian – South African run telescope has been scanning the southern skies since it began operating in late December 2014, looking for “transients” – new objects which appear in the sky for the first time. Since then, over 60 newobjects have been discovered, most of them being erupting or exploding stars. However, the MASTER-SAAO telescope has just discovered its first comet. Please go here to read all about the discovery and see pictures on the SAAO website
Gemini North Observatory has released new images of Comet C/2012 S1 (ISON) racing toward what promises to be an uncomfortably close rendezvous with the Sun. By late November the comet could present a stunning sight in the twilight sky and remain easily visible, or even brilliant, into early December of this year.
The images from Gemini Observatory are presented as a time-sequence, spanning early February through May 2013. They clearly show the comet’s unexpectedly high activity despite the fact that it is still a long way from the Sun and Earth. The information provided by this series gives vital clues as to the comet’s overall behavior and its potential to present a spectacular show when it comes closer to the Sun. Predictions about a comet’s brightness are notoriously difficult as they have to be made without knowing if the comet has the right composition to survive an extremely close brush with the Sun toward the end of November and go on to become the predicted early morning spectacle from Earth in early December 2013.
This time sequence from Gemini Observatory represents the comet while it was between roughly 730-580 million kilometers, or 4.9-3.9 astronomical units from the Sun, or just inside Jupiter’s orbit. Each image in the series, taken with the Gemini Multi-Object Spectrograph at the Gemini North telescope on Mauna Kea, Hawai‘i, shows the comet in the far red part of the optical spectrum, emphasizing that the comet’s dusty material is already escaping from what astronomers describe as a “dirty snowball.”
The images show the comet sporting a well-defined parabolic hood in the sunward direction that tapers into a short and stubby tail pointing away from the Sun. These features form when dust and gas escape from the comet’s icy nucleus and surround that main body to form a relatively extensive atmosphere called a coma. Solar wind and radiation pressure push the coma’s material away from the Sun to form the comet’s tail, which is seen here at a slight angle.
At last I got my pictures of the beastly thing! Not very good but I got them, that’s the main thing. I also experienced the very brief but intense thrill of thinking that I had photographed the comet breaking up. Unfortunately it hadn’t and I had to come down to Earth very quickly again.
Comet PANSTARRS’s closest approach to Earth will be on 5 March 2013 when a mere 1.09 au will separate us from this visitor from the outermost reaches of the Solar System. It’s closest approach to the Sun (perihelion) will be on 10 March 2013. Original estimates predicted that it would brighten to an apparent magnitude of 0 (roughly the brightness of Alpha Centauri A in Centaurs or Vega in Lyra). Optimistic estimates in October 2012 predicted a magnitude of -4 (roughly equivalent to Venus). In January 2013 brightening slowed down and revised estimates suggested it might only brighten to magnitude +1 (roughly Spica in Virgo). During February the increase in brightness has slowed even further, so that the magnitude at perihelion is now predicted to be between +2.5 and + 3.0 (Markab in Pegasus and Deneb in Aquila).
This comet is now visible with binoculars from down here in the Cape, reports Dieter Willasch. It is very close to the Sun and Southern Sky viewers have to look very carefully to find it.. Dieter managed to get a good shot of the comet shortly after 18:30 on Thursday the 28th February from Somerset West. The image can be viewed on his website Astro-Cabinet, which also has many other excellent examples of his astrophotography.
Comet C/2012 S1 (ISON) was discovered on the 21st September.2012 by two Russian astronomers using the 40 cm telescope of the International Scientific Optical Network (ISON) near Kislovodsk. Kislovodsk is a spa city in the Stavropol Krai, in the North Caucasus region of Russia, between the Black and Caspian Seas.
In September 2012 Vitali Nevski loaded the images of a routine survey he was conducting, into a computer program designed to detect asteroids and comets moving between images. The results turned up a rather bright object with unusually slow movement, which suggested to him it was located way beyond the orbit of Jupiter, but he couldn’t tell if the object was a comet or not. His colleague, Artyom Novichonok, then booked time on a larger telescope to take another look and, a day or so later the new images revealed that Nevski and Novichonok had, in fact, discovered a comet which was named Comet ISON. A database search showed it had already been seen in images taken by other telescopes earlier that year and, in fact, as far back as late 2011 but nobody had identified it as a comet.
On the other side of the world, a team from the University of Maryland and NASA’s Jet Propulsion Laboratory are employing NASA’s Deep Impact spacecraft to track ISON and gather more detailed information. Deep Impact, as you might remember, smashed a probe into comet Tempel ! in June 2005, subsequently executed a close flyby of comet Hartley 2 and then carried out detailed scientific observations of comet Garradd. The Deep Impact team now has its sights set on comet ISON which, although it is still more than 700 million km from the Sun, is apparently already active, because in January 2013 it had a tail more than 64 000 km long. At present comet, ISON can barely be distinguished from the stars in the constellation of Cancer.
Comet ISON is expected to reach perihelion on the 28th November 2013 when it passes within 1,2 million km (0,012 AU) of the Sun’s surface and at its closest approach to earth on the 26th December 2013 it will be about 64 million km away (0,427 AU) from the surface of our planet. It is thought that this is Comet ISON’s first visit to the Sun and the fact that it is a “new” comet probably means it will contain larger than usual amounts of volatile material, so its close approach to the Sun could result in an enormous outgassing of this material, providing a visual display of note, as seen from Earth. The close approach could also cause the comet to break up, but nobody can predict that with any certainty, as was shown by comet Elenin in 2012.
The comet is currently very faint, but as it approaches the Sun, it will steadily brighten and should be easily picked up by experienced amateur astronomers with CCD equipment in the coming months. It will be a binocular object by September/October 2013, and eventually become visible to the naked eye in early November. Depending on its eventual brightness, which cannot be accurately predicted, the comet should remain visible to the naked eye from early November 2013 to mid-January 2014. Some estimates say it will have a very long tail and should be as bright as the Full Moon, making it potentially visible during the day!
And here we finally have it, comet Lemmon snapped as it moves past the South Celestial Pole. Camera: Nikon 5000D,
Lens: Nikkor Vr 18-2– mm, F3.5-5.6G,
Focal length 200 mm, manual, VR off, White balance: Daylight,
Stacked: 20 frames.
Post-production Auke Slotegraaf.
Comet C2012 F6, commonly known as comet Lemmon, is proving rather difficult to find and even more difficult to photograph from my location. In a week from now I might be able to get a better view from the northern Cederberg, but I have a sneaking suspicion the southern horizon is going to be too high from our location there. It should be very well placed for photographing then, as it is expected to be just a hairsbreadth west of NGC 104 (47 Tucana) so I will hold thumbs and wait and see.
Comet Lemmon was discovered on 23rd March 2012 by Alex Gibbs of the Mount Lemmon Survey while routinely scanning for near earth objects. At that point it was very faint at magnitude 20,7 and the prediction was that it would not improve to more than magnitude 7,7 but comet Lemmon has surprised everyone and looks as if it might reach magnitude 2 by the 21st March and be a naked eye object from dark sites.
Comet PANSTARRS, officialy known as Comet C/2011 L4 was first spotted in in June 2011 by the Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) telescope near the summit of Haleakala in the island of Maui in Hawaii. Initially it was at magnitude 19 but has brightened to magnitude 13,5. Its closest approach to the Sun (perihelion) will be on the 10th March and its closest distance to the Earth on the 5th March will be 1,09 astronomical units (au).
First estimates of its brightness were that it might reach an apparent magnitude of 0 (comparable to alpha-Centauri A or Vega). A revised estimate in October 2012 predicted that it might brighten to magnitude -4 (more or less Venus) and the current estimates are more conservative, predicting a magnitude of +1. For a comparison, Capella B is +0,96 & Spica 1,04.
Comet C/2011 L4 has come a long way as it is estimated thet it probably left its home in the Oort Cloud about a million years ago. Currently it is visible about 15 degrees above the horizon between Telescopium and Microscopium.
More about comet C/212 S1 (ISON) which is expected to be a major spectacle in an upcoming post.