编辑“︁NGC 6118”︁（章节）

== 超新星 SN 2004dk ==
2004年8月1日，James Graham 和李衛東提出在NGC 6118發現[[超新星]]SN 2004dk的第一篇報告。他們在[[利克天文台]]超新星巡天（Lick Observatory Supernova Search，LOSS）計畫中口徑76公分[[卡茨曼自动成像望远镜]]拍攝的影像中發現該超新星<ref name="iauc8377">{{cite web
  | title = Supernova 2004dk in NGC 6118
  | work = International Astronomical Union Circular 8377
  | name = 
  | publisher = Smithsonian Astrophysical Observatory
  | date = 2004-08-02
  | url = http://www.cbat.eps.harvard.edu/iauc/08300/08377.html#Item2
  | accessdate = 2011-07-05
  | archive-date = 2017-11-16
  | archive-url = https://web.archive.org/web/20171116185411/http://www.cbat.eps.harvard.edu/iauc/08300/08377.html#Item2
  | dead-url = no
  }}</ref>。
<!-- NEED to find info on max magnitude.<ref name="rajala04">
{{cite web
  | title = Prompt photometric identification of young SNe using the robotic Palomar 60" telescope
  | work = SN 2004dk
  | name = Anne Rajala, Derek Fox, Avishay Gal-Yam
  | publisher = California Institute of Technology
  | date = 2004-08-03
  | url = http://www.astro.caltech.edu/~avishay/phototyping/
  | accessdate = 2008-12-07
}}</ref> -->

SN 2004dk起初被欧洲南方天文台的天文學家 Fernando Patat 等人於2004年8月4日歸類為[[Ib和Ic超新星|Ic超新星]]<ref name="iauc8379">{{cite web
  | title = Supernova 2004dk in NGC 6118
  | work = International Astronomical Union Circular 8379
  | name = 
  | publisher = Smithsonian Astrophysical Observatory
  | date = 2004-08-04
  | url = http://www.cbat.eps.harvard.edu/iauc/08300/08379.html#Item3
  | accessdate = 2011-07-05
  | archive-date = 2017-11-16
  | archive-url = https://web.archive.org/web/20171116185214/http://www.cbat.eps.harvard.edu/iauc/08300/08379.html#Item3
  | dead-url = no
  }}</ref>。這型超新星是質量超過太陽8倍的恆星核心耗盡了可以核融合的元素後的恆星死亡。一般來說超新星爆炸時會觀測到氫和氦存在的證據，但[[聯星]]系統內因為另一顆恆星的重力會將超新星前身星的外層剝離一定程度，這樣的超新星爆炸將只剩下[[金屬量|重元素]]。Ib超新星沒有氫，而Ic超新星沒有氫和氦。

接下來數個星期[[加州大學柏克萊分校]]的[[阿列克謝·菲利潘科]]等人在SN 2004dk的光譜中發現了明顯的[[譜線|He I吸收線]]，因此該超新星的分類被改為Ib<ref name="iauc8404">{{cite web
  | title = Supernovae 2004dk, 2004dw, 2004dy, AND 2004eg
  | work = International Astronomical Union Circular 8404
  | name = 
  | publisher = Smithsonian Astrophysical Observatory
  | date = 2004-09-11
  | url = http://www.cbat.eps.harvard.edu/iauc/08400/08404.html#Item1
  | accessdate = 2011-07-05
  | archive-date = 2017-11-16
  | archive-url = https://web.archive.org/web/20171116185530/http://www.cbat.eps.harvard.edu/iauc/08400/08404.html#Item1
  | dead-url = no
  }}</ref>。