 Comet Pojmański photographed by John Drummond on 24 February 2006. | |
| Discovery[1] | |
|---|---|
| Discovered by | Grzegorz Pojmański |
| Discovery date | 2 January 2006 |
| Orbital characteristics[2][3] | |
| Epoch | 24 March 2006 (JD 2453818.5) |
| Observation arc | 247 days |
| Earliestprecovery date | 25 December 2005 |
| Number of observations | 600 |
| Aphelion | ~2,530 AU |
| Perihelion | 0.555 AU |
| Semi-major axis | ~2,380 AU |
| Eccentricity | 0.99977 |
| Orbital period | ~45,000 years |
| Inclination | 92.736° |
| 211.34° | |
| Argument of periapsis | 351.19° |
| Mean anomaly | 0.0003° |
| Last perihelion | 22 February 2006 |
| TJupiter | –0.042 |
| EarthMOID | 0.445 AU |
| JupiterMOID | 2.474 AU |
| Physical characteristics[4][5] | |
Mean radius | 0.867 km (0.539 mi)[a] |
| Comet total magnitude (M1) | 7.4 |
| Comet nuclear magnitude (M2) | 14.5 |
| 4.5 (2006 apparition) | |
Comet Pojmański, formally designated asC/2006 A1, is anon-periodic comet that became barely visible to the naked eye in early 2006. It is the only comet discovered by Polish astronomer,Grzegorz Pojmański.
Pojmański discovered the comet as a 12th-magnitude object in the night sky using theLas Campanas Observatory inChile as part of theAll Sky Automated Survey (ASAS).[6] Kazimieras Cernis at the Institute of Theoretical Physics and Astronomy atVilnius,Lithuania, located it the same night and before the announcement of Pojmański's discovery, in ultraviolet images taken a few days earlier by the SWAN instrument aboard theSOHO satellite.[7] A pre-discovery picture was later found from 29 December 2005.[1]
At the time of its discovery, the comet was roughly 181 million km (1.21 AU) from the Sun. But orbital elements indicated that on 22 February 2006, it would reachperihelion at a distance of 83 million km (0.55 AU).
The comet moved on a northward path across the night sky, and reached maximum brightness around the beginning of March. Comet Pojmański reached the very fringe of naked-eye visibility at aboutmagnitude 5, and was best visible throughbinoculars or atelescope. It could be found in the dawn sky within the constellationCapricornus, close to the horizon in the northern hemisphere, during late February, but viewing circumstances became better for the northern hemisphere as the comet departed southern skies and continued north.
By early March, the comet was located inAquila, theEagle, and by March 7 was located in the constellationDelphinus.[7]
Comet Pojmański brightened more than initially estimated, perhaps due to over-cautious estimates by astronomers. It had previously been estimated to reach a maximum brightness of around 6.5 magnitude, but became considerably brighter.
During the comet's appearance, it sported a tail of three to seven degrees (six to fourteen times the apparent lunar diameter) and acoma of up to about 10arcseconds.
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