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2001 Q4 NEAT NEAT计划1.2米斯密特望远镜8月24.40拍摄的CCD照片上发现一颗20等彗星,24、26、27日的照片显示为均匀的星云状,直径8",总亮度17.3-17.8等。 IAU Circular No. 7695 (2001 August 28)首次公布了这颗彗星,但是给出了一个不是很确定的轨道,彗星可能在2005年8月25日通过近日点,近日距稍超过4AU,这是因为彗星移动非常缓慢,马斯登的轨道显示彗星发现时距离太阳可能超过11AU。Kazuo Kinoshita9月5日在他的网站发布了新的轨道根数,使用了8月24-31日的25个观测数据,表明彗星将在2004年5月23日从0.99AU通过近日点,这个轨道显示彗星有可能会成为一个比较明亮的目标。9月10日IAU Circular No. 7711确定了Kazuo Kinoshita的计算,彗星于2004年5月26日通过1AU的近日点。格林还写道,近日点日期还有几个星期的不确定误差,但这颗彗星2004年5-6月期间可能成为一个普通双筒望远镜甚至肉眼目标,彗星发现时离太阳10.1AU。 2001年末到2002年,彗星慢慢增亮,2003年初,彗星仍暗于15等,但是稳定增长。5月底达到14等,7月初13等,9月中旬12等,从9月开始,南半球的天文爱好者开始目视跟踪观测,彗发直径在0.6-1.2弧分,爱好者7月的CCD照片也呈现指向北方的扇形短尾。9月底,这条尾巴向西北延伸出0.8弧分,2003年结束时,彗星亮度超过10等,直径约2弧分,一条微弱的扇形彗尾向东伸展4弧分。 CBAT预测彗星5月中旬亮度最大可到0.9等,虽然几个月都没有更新亮度参数,但一些有经验的天文爱好者密切监视着这颗彗星。德国的Andreas Kammerer查看了到2003年11月所有的观测数据,推测彗星的最大亮度可达2等,日本Seiichi Yoshida也根据过去的观测认为最大亮度可达到2等。 进入2004年,彗星继续稳步增亮,2月中旬8等,3月中旬7等,4月初6等,而在中旬前达到5等,这期间彗发也在变大,2月初2弧分,3月中旬5弧分,4月开始的时候10弧分,4月中旬15弧分。 彗星终于在5月3/4日晚上出现在北半球天文爱好者的视野,美国德克萨斯,新墨西哥,亚利桑那州,加利福尼亚南部,和夏威夷的观测者,在大犬座ε星下方很低的高度看到了彗星,大部分观测者形容彗星直径7到10弧分,很像个球状星团,尾巴很难看到。同时,南半球的观测者给出的亮度在3.2-3.6等之间,彗星在5月6日通过近地点,接下来的一周对北半球的观测者来说快速升高,在黑暗的环境下,观测者指出亮度达到2.8至3等,彗发直径一般估计为20-30弧分,最初尾巴很短,但很快变长并有活跃的丝状结构,此外,很多观测者指出,彗发向阳面的一侧异常明亮,很多处理后的数字照片显示出包围核心的壳状结构。5月中旬期间,因为彗星展现出很大的彗发,导致许多亮度估计的差异,星等数据有1等左右的差别,平均亮度约3.4等,彗发直径25-30弧分。之后彗星逐渐变暗,5月18日4等,5月25日大约5等,最后日期彗发直径估计10-15弧分。 英国的观测者描述,5月10日,20x80双筒镜中彗星亮度4等,彗发直径15弧分,凝聚度5,尾巴长0.5度,5月16-23日,在巴伐利亚阿尔卑斯山观测,16日使用10x25双筒镜看到2.7度长的彗尾,亮度3.5等,20日变暗到4.4等,1.5度长的尾巴,它继续缓慢变暗,6月12日6.1等,仍然有一条0.5度的暗弱彗尾。8月中旬变暗至8.5等,但仍然可以用双筒镜观测,9月中旬就需要使用望远镜观测了,9月18日用30厘米反射镜估计亮度10.2等。
Comet C/2001 Q4 (NEAT)
Credit & Copyright: Loke Kun Tan (StarryScapes)
The Tails of Comet NEAT (Q4)
Credit & Copyright: Chris Schur
Copyright © 2004 by Gianluca Masi and Franco Mallia (Las Campanas Observatory, Chile) This image was obtained on 2004 April 16.99, while using the SoTIE telescope in Las Campanas. A set of images were collected to create a mosaic, covering about 0.7 deg. Each area was imaged using a total integration time of 3 minutes. Then the frames have been shifted taking the comet motion into account, in order to keep the higher detail. The tail of the comet is clearly visible; the object was at about 25 deg above the horizon. On the bottom right, the region close to the false nucleus shows clear dust shells.
Copyright © 2004 by Gianluca Masi and Franco Mallia (Las Campanas Observatory, Chile)
This image was obtained on 2004 April 16.99, while using the SoTIE telescope in Las Campanas. A set of images were collected to create a mosaic, covering about 0.7 deg. Each area was imaged using a total integration time of 3 minutes. Then the frames have been shifted taking the comet motion into account, in order to keep the higher detail. The tail of the comet is clearly visible; the object was at about 25 deg above the horizon. On the bottom right, the region close to the false nucleus shows clear dust shells. Look West for a NEAT Comet
Credit & Copyright: Jimmy Westlake (Colorado Mountain College)
Copyright © 2004 by Giovanni Sostero (Remanzacco Observatory, Italy)
Copyright © 2004 by Günter Kerschhuber (Oberösterreich, Austria)
This image was obtained by G. Kerschhuber on 2004 May 13.91. It is a composite of sixty-five 40-second exposures obtained with a Pentacon 300mm and a Starlight SXV-H9.
Copyright © 2004 by Jerry Armstrong (Winston, Georgia, USA) and Fernbank Science Center (Decatur, Georgia, USA)
This image showing detail within the inner coma was obtained by J. Armstrong on 2004 May 12.06. It is a 20-second exposure obtained with a Meade 14-inch LX200GPS Schmidt-Cassegrain Telescope and an SBIG ST-1001 CCD camera. North is up. The camera was on-loan from the Fernbank Science Center.
Copyright © 2004 by Rolando Ligustri, G. Degano, and L. Furlanetto (Talmassons, Italy)
Copyright © 2004 by Anthony Arrigo (Park City, Utah, USA)
This image of comet NEAT near the Beehive Cluster (M44) was obtained by A. Arrigo on 2004 May 15. It is a composite of eight 30-second exposures obtained with a Sony DSC-F717 digital camera and 1.7x teleconverter. The camera was piggy backed on a 120mm f/5 refractor sitting on a Losmandy G11 mount.
Copyright © 2004 by Carlos Vázquez Darias (Tenerife, Canary Islands)
This image was obtained by C. V. Darias on 2004 May 15.94. It is a 2.5-minute exposure using Fuji X-tra 400 film and a 20-cm Celestron Schmidt camera. The image shows the comet as it was moving past the open cluster M44 in Cancer.
Copyright © 2004 by Javier Alonso Labrador (Tenerife, Canary Islands)
This image was obtained by J. A. Labrador on 2004 May 15.94. It is a 2-minute exposure using a Canon D60 digital SLR camera set at 400 ASA, with an 85mm f/1.2 lens. The image shows the comet as it was moving past the open cluster M44 in Cancer. Copyright © 2004 by Jim Melka (St. Louis, Missouri, USA) This image was obtained by J. Melka on 2004 May 16.11. Four 1-minute exposures were obtained using a Canon D60 digital SLR camera set at 400 ASA, with 12-inch f/4.1 Newtonian reflector. These images were subsequently stacked using Registax 2.0 Freeware.
Copyright © 2004 by Luca Buzzi, Mauro Auteri, and Andrea Aletti (G. V. Schiaparelli Astronomical Observatory, Varese, Italy)
This image was obtained by L. Buzzi, M. Auteri, and A. Aletti on 2004 May 16.89. They were using a 14-inch Celestron Schmidt camera stopped down to 280mm. This 4-minute exposure was obtained with 400 ISO film.
Copyright © 2004 by Mikael Moeller, Leif Moeller and Mogens Winther (Val d'Aosta, Italy)
This image was obtained by M. Moeller, L. Moeller and M. Winther on 2004 May 19.95. It is a composite of eleven 60-second exposures obtained with a Canon EOS D10 camera mounted at prime focus on a 1140mm refractor.
Copyright © 2004 by Alessandro Cipolat Bares (Val d'Aosta, Italy)
This image was obtained by A. C. Bares on 2004 May 22.88. It is a composite of four 60-second exposures obtained with an FSQ 106 and an SXV-H9 CCD camera.
Copyright © 2004 by Giovanni Sostero (Remanzacco Observatory, Italy)
This image was obtained by G. Sostero on 2004 May 24.0. It is a 300-second exposure obtained with a Canon EOS D300 camera and an Intes 15-cm Maksutov astrograph. The field of view measures 1° by 1.4°.
Comet NEAT and the Beehive Cluster
Credit & Copyright: Jimmy Westlake (Colorado Mountain College)
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