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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

8293 results found.

  1. GRB 060110: Mitsume optical observations
  2. GRB 060110: Swift-BAT refined analysis
  3. GRB 060110: IR Candidate Afterglow
  4. GRB 060110: Super-LOTIS observations
  5. GRB 060110: Optical observation
  6. GRB 060110: Correction
  7. GRB 050110: IR Observations
  8. GRB 060110: Optical limit
  9. GRB 060110: Swift-BAT detection of a burst
  10. GRB 060109: Swift Detection of a long burst
  11. GRB060108: Faulkes Telescope observation
  12. GRB060108: Swift detection of its 100th GRB
  13. GRB 060105: Swift/UVOT upper limits
  14. GRB 060102 - no XRT afterglow
  15. GRB060105 : Kiso optical observation
  16. GRB060105: Swift detection of a bright long burst
  17. Swift-BAT trigger 175653 is not an astrophysical source
  18. GRB051211B: optical observations
  19. GRB 051221B: Optical Observations with Kuiper 1.54m
  20. GRB 051227: optical observation
  21. GRB 051227: P60 Observations
  22. GRB 051227: R-band object in the XRT error circle
  23. GRB 051227: Further analysis of the Swift-BAT burst
  24. GRB 051227: Swift detection of a burst
  25. GRB051117B: optical observation
  26. GRB 051221: Continued fading of optical afterglow
  27. GRB 051221A: RAPTOR Fading Counterpart Constraint
  28. Swift-BAT detection of a possible burst
  29. GRB 051221: Swift/UVOT upper limits
  30. GRB 051221: Swift detection of a bright short burst
  31. GRB051211A: possible optical candidate
  32. GRB 051215: A short GRB in a cluster?
  33. GRB 051211B: Swift XRT confirmation of the afterglow
  34. GRB051211B: Liverpool Telescope observation
  35. GRB 051211b: RTT150 optical observations
  36. GRB 051211B: Swift XRT Observations
  37. GRB 051211B: a possible optical detection by TAROT
  38. An extraordinary long burst on December 3 from SGR1806-20
  39. Possible resuming of the SGR 1806-20 activity
  40. GRB051111: Suzaku WAM observation of the prompt emission
  41. GRB051111: Rc optical observations
  42. GRB 051117A: Refined analysis of the Swift-BAT burst
  43. GRB 051117B: Swift detection of a burst
  44. GRB050925: analysis of the XMM-Newton observation
  45. GRB 051111: Swift-BAT refined analysis
  46. Faulkes Telescope R-band detection of GRB051111
  47. GRB 051109a: IR Detections
  48. GRB051103: MASTER: OT limit and host galaxy candidates
  49. GRB 051105A, 2nd epoch optical observations
  50. GRB051103:_MASTER_optical_observations
  51. GRB 051105: Optical limit
  52. GRB051016B: optical observation
  53. GRB051028: optical observations
  54. GRB051028: confirmation of the afterglow
  55. GRB051028: WHT optical candidate
  56. GRB051028:MASTER observations
  57. GRB051028:MASTER optical observations
  58. GRB051012: Swift-XRT analysis
  59. GRB051021A: Swift XRT refined analysis
  60. GRB051022: Optical Observations
  61. GRB051021b: Magellan IR Imaging
  62. GRB 051021, SMARTS optical/IR observations
  63. GRB 051021B: Swift detection of a burst
  64. GRB 051021: Optical observations
  65. GRB 051021: Optical observations and candidate afterglow
  66. GRB051021.63
  67. GRB051021.6: MASTER optical observation
  68. GRB 051016b: Optical limit
  69. Afterglow candidate of GRB 051016B observed at Lulin
  70. GRB 051016b: Gemini Near IR Observations
  71. GRB 051016: Swift-BAT refined analysis
  72. Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
  73. GRB050805A: Rc optical observations
  74. GRB051008: optical candidate
  75. GRB051011: MASTER optical observation
  76. GRB051008 - Swift UVOT upper limits
  77. GRB 051008, optical observations
  78. GRB 051008: Swift UVOT Candidate
  79. GRB050925: Swift/XRT limits
  80. GRB050925: Faulkes Telescope North R-band limit
  81. GRB050922C: Optical Observations
  82. GRB050911: Upper limit on X-ray afterglow
  83. Swift-BAT trigger 155072 is probably not a GRB
  84. GRB050914: XRT position probably due to cosmic ray
  85. GRB 050911, optical content of Swift/XRT error box
  86. GRB050911: Swift-XRT position
  87. GRB 050906: Possible X-ray Counterpart
  88. GRB050908 : Swift-XRT refined analysis
  89. GRB 050908: Optical observations
  90. Gemini Spectroscopy of GRB 050908
  91. GRB 050908: P60 Confirmation of Optical Afterglow
  92. GRB 050908: Optical Observations
  93. GRB 050904: Subaru Optical Spectroscopy
  94. GRB 050904: Keck I-band Imaging
  95. GRB 050906: Bright galaxy in BAT error box
  96. GRB 050904: TAROT optical measurements
  97. GRB 050827: Optical Limit
  98. GRB 050826 : Lulin R band observation
  99. GRB 050826: Optical Candidate
  100. GRB050824: MASTER final analysis of the OT observations

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