SOHO Introduction
STEREO Introduction

Official Comet Hunting Guide
Report a SOHO Object
Report a STEREO Object
Recent Reports

Basics (via NASA)
Sungrazing Comets

SOHO Kreutz-group
SOHO Non-Kreutz
STEREO/SECCHI
Periodic Discoveries

Data
FAQs
LASCO C3 Transits
STEREO L4/L5 Campaign
STEREO JAVA Orbit Tool
C2/C3 Comet Tracks

NASA Citizen Science
SOHO Real-Time Images
Comet McNaught in 2007
15-years of SOHO Comets
@SungrazerComets
Other Links

SOHO/LASCO X-Comets


Definition of SOHO X-Comets

Occasionally, objects will appear in consecutive LASCO images that have some properties (velocity, appearance, brightness, etc.) that resemble past comets but lack sufficient evidence to be officially declared a comet. In these cases we declare the object to be a SOHO x-comet. A record of SOHO x-comets are kept internally in the rare case that new evidence emerges to convince us the object is indeed real. There are no concrete rules that must be satisfied for a comet to be declared real except that it must be observed in at least four consecutive images. The remaining criteria is based on how well the object resembles properties established by the greater than 800 comets LASCO has observed.

The two most common reasons why an object is declared a SOHO x-comet are:

  • 1) Comet is not visible in at least four consecutive images due to disintegration or data gaps.
  • 2) Comet appears too dim to make a doubtless confirmation (barely above the background noise level).

X-Comet List

The following list was compiled by Michael Oates, Jonathan Shanklin, Derek Hammer and Mr Sungrazer...

               Time of
#.    Date    First Image  #Images  Discoverer       Notes
=====================================================================
1.  1996/01/29   16:33 (C3)   8     X. Leprette
2.  1996/04/01   16:59        2     M. Meyer
3.  1996/04/03   02:24        2     M. Meyer
4.  1996/04/10   00:57        2     M. Meyer
5.  1996/04/13   09:50        1     M. Meyer
6.  1996/05/12   18:30        2     M. Oates
7.  1996/05/13   13:46        2     M. Oates
8.  1996/05/19   07:29        1     M. Oates
9.  1996/08/30   18:59  (C3)  5/6   R.Kracht  -- Inconsistent positions. Variable brightness. 
					         Needed more images.
10. 1997/04/14   19:06	      1     M. Oates
11. 1997/04/25   02:30        2     M. Oates
12. 1997/04/26   11:31	      2     M. Oates
13. 1997/06/19   17:23        4     X. Leprette
14. 1998/03/27   10:23        3     M. Meyer
15. 1998/03/27   23:07        3     M. Oates
16. 1998/04/28   14:45        4     M. Oates
17. 1998/06/02   22:04        3     M. Oates
18. 1998/11/07   05:18        4     M. Oates
19. 1998/12/01   13:32        2     M. Oates
21. 1999/03/31   03:30        4     M. Oates
22. 1999/06/24   08:54       3/4    M. Oates
23. 1999/09/21   03:06       3/4    M. Oates
24. 1999/09/21   12:54        4     M. Oates
25. 1999/12/14   10:31        9     M. Oates
26. 2000/06/10   19:31        8     M. Oates
27. 2000/06/23   07:54        8     M. Oates
28. 2001/03/21   11:50        3     M. Oates
29. 2001/04/02   14:06        4     X. Leprette
30. 2001/04/25   10:06       3/4    T. Scarmato
31. 2001/05/23   15:50        5     M. Boschat
32. 2001/05/27   16:50        7     M. Oates
33. 2001/06/06   13:31        3     M. Oates
34. 2002/04/26   10:26        3     X.-M. Zhou
35. 2002/05/13   00:06       3/4    X. Leprette
36. 2002/06/13   10:54       3/4    X. Leprette
37. 2002/06/23   18:06        3     R. Kracht
38. 2002/07/01   19:31        3     M. Boschat
39. 2002/11/24   10:56       3/4    R. Matson
40. 2002/12/06   10:06        3     R. Kracht
41. 2002/12/20   08:30        6     X. Leprette
42. 2003/05/05   17:26        3     R. Matson
43. 2003/05/19   23:50        3     D. Evans
44. 2003/05/31   01:54        5     T. Hoffman
45. 2003/05/31   02:30        6     P. Shkreby
46. 2003/07/06   13:18 (C3)  4/6    P. Shkreby
47. 2003/08/25   11:42 (C3)   5     M. Boschat
48. 2003/10/16   03:06        4     R. Matson
49. 2003/12/05   20:42 (C3)  4/5    R. Matson
50. 2004/08/07   04:18 (C3)  5/6    J. Danaher	
51. 2004/11/08   23:06       3/5    T. Hoffman  -- Probable non-group. Faded too quickly.
52. 2004/12/09   18:42 (C3)  5/6    R. Matson   -- Probable Kreutz. Not enough images due to data gap.
53. 2005/10/31   21:30	     3/4    T. Hoffman  -- Possible Kreutz. Inconsistent shape/brightness.
					           Too few images.
54. 2005/11/06   17:54       3/4    H.Su        -- Possible Kreutz. Too few images. Inconsistent shape.
55. 2006/04/08   09:32       3/4    J.Ruan      -- Probable Kreutz. Too few images. Inconsistent position(s).
56. 2006/07/14   04:30        3     T.Hoffman   -- Probable Kreutz. Looked good, but too few images.
57. 2003/10/17   05:54        4     B. Zhou     -- Probable Kreutz. Too faint/diffuse. 
All x-comets were visible in C2 images unless otherwise noted.