Comet C/2002 C1 Ikeya-Zhang


Prospects for Ikeya-Zhang

Introduction

This comet is the first to reach naked eye brightness since the Hale-Bopp graced our skies back in 1997. It is in fact turning out to be slightly better than expected and should put on a respectable show towards the end of March and into April.

The comet reached perihelion, its nearest point to the sun, on 18 Mar 2002, and after this time starts to swing away from the sun and towards the Earth as this diagram shows. The last week of March and the first of April will probably be the best opportunity to see the comet in a dark sky. Although it is probably at maximum brightness about now, and will decline slowly from now on, visibility will actually improve: the moon moves past full so its light no longer interferes, and the comet's increasing separation from the sun as it moves north means that it will be seen long after the last vestiges of twilight have disappeared.

Where to Look

Ikeya-Zhang will be visible in the north-west in the evening, and adds to a plethora of planets already visible in the west after sunset. Please visit Spaceweather for a finder chart to help locate it in relation to the sky, and JPL for a plot of its course. Its brightness around this time is predicted to be magnitude 3.5 to 4, a reasonably easy naked eye object in a sufficiently dark sky, but otherwise binoculars or a small telescope will show it in all its glory!

The best time to start looking is at about 7.30pm, when the planet Venus, low but unmistakably bright to the WNW, will act as a guide. Tracing upwards along the line of the ecliptic for about 20 degrees you will find Mars, distinctly red but a lot fainter than the brilliance it displayed when it was at opposition low on the southern horizon last summer. Take that same distance and swing it round clockwise about 60 or 70 degrees and you will land almost on the comet. Ikeya-Zhang is moving northwards at about 1.5 degrees a day, so these directions hold approximately true over Easter, but each night it moves progressively further to the right so you should allow for this movement.

If you carry on up from Mars for another 20 degrees or so you will find Saturn, appearing as a reasonably bright (but non-twinkling) yellow star in the constellation of Taurus. It contrasts with the nearby red star of Aldebaran, and below and to the right of it is the beautiful star cluster of the Pleiades, or Seven Sisters. Continue on up from Saturn another 15 degrees and you will see Jupiter, still very bright in Gemini.

Saturday night (30 Mar), if clear, should prove rewarding as Ikeya-Zhang will be almost on top of beta-Andromedis, a bright star in the constellation of Andromeda. On Thursday 4th April it will be only a couple of degrees from the Andromeda Spiral Galaxy, which should make a fine binocular sight and photograph - it remains to be seen which will be the brighter at this stage.

4 planets and a comet make an easy challenge for a few minutes spent outside in the early evening - it's nice to have something accessible at a convenient hour for a change! Just let your eyes adapt to the dark for a few minutes and try and get away from city lights for a better view.


What we have seen...

As of the 28th March I have now seen the comet 4 times, on the March 22nd, 26th, 27th & 28th between 7.15 and 8pm. It is a fine sight in binoculars with a small star-like nucleus at the head of a slender tail that stretches up almost vertically for about 3 degrees.

The lights of London and moonlight have so far conspired to prevent my seeing it in a dark sky, so I find it only just discernable to the naked eye. However, I reckon it should be easily visible in a truly dark sky, and I hope that I can put this to the test in the dark skies of Hay-on-Wye over Easter. Camera will be at the ready too!

My first attempt to photograph the Ikeya-Zhang proves successful: despite horrendous light pollution from London the comet is easily visible to the left of this picture, with its fuzzy tail pointing upwards...

Ikeya-Zhang on 29 Mar 2002

Ikeya-Zhang on 29 Mar 2002 20:21UT, from Hurst Green, Surrey. The star above and to the right of the comet is Beta-Andromedis, which it will pass just beneath on the 30th, and will reach the third star in the row on April 4th. The comet is at an altitude of 20 degrees and lies in the thick of light pollution from London.

Minolta Dimage 7, 20.3mm, 16s @ f/3.5, running at ISO800

Easter unfortunately proved cloudy in Hay so I could not see Ikeya-Zhang until my return to London's blighted skies. There is no way that any of my attempts to photograph it could rival any of the excellent dark-sky pictures on the Spaceweather gallery.

Nevertheless it proved possible to track its progress across the sky from night to night (and on 7th April the comet was very near a star so it was possible to combine a series of pictures taken 1 minute apart into a movie). The rectangles on the path of the comet below represent the areas occupied by a succession of photographs - click on them or the dates to see them...

My more recent attempts at photography through an anti-light pollution filter have proved successful in tracking the comet's nucleus. However, the filter's general darkening effect requires longer exposure times, and with the camera having a 32s maximum exposure time and the tendency for electrical noise to interfere with long exposures taken at high sensitivity, the tail has proved stubbornly elusive.

 


External Links...

Link to Spaceweather picture gallery


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