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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"

28061 results found.

  1. Swift Trigger 381434 is not a GRB
  2. Trigger 381434: Swift detection of a possible burst
  3. GRB 091221: Skynet/PROMPT Detections
  4. GRB 091221: Fermi GBM Observation
  5. GRB 091117: Swift-XRT late time observations
  6. GRB 091221 Swift-BAT refined analysis
  7. GRB 091221: Swift/UVOT refined analysis
  8. GRB 091221: Swift-XRT refined analysis
  9. GRB 091221: Enhanced Swift-XRT position
  10. GRB 091221: UVOT Confirmation of an Optical Afterglow
  11. GRB 091221: ROTSE-III Detection of Optical Counterpart
  12. GRB 091221: Swift detection of a burst
  13. Swift trigger 379449 (possible GRB) is not a burst
  14. GRB 091215: Faulkes Telescope North observations
  15. Trigger 379449: Swift detection of a possible burst
  16. GRB 091208A: Suzaku WAM observation of the prompt emission
  17. GRB 091208A: GAO 150cm telescope Optical Observation
  18. GRB091208A: Swift/UVOT refined analysis
  19. GRB 091208B: optical observations
  20. GRB 091208B: GROND observations
  21. GRB 091208A: Swift-XRT observations
  22. GRB091208B: NOT optical observations
  23. GRB 091208B: Swift-XRT refined analysis
  24. GRB 091208B, Swift-BAT refined analysis
  25. GRB 091208A Swift-BAT refined analysis
  26. GRB 091208A, RIMOTS optical upper limits
  27. GRB 091208B: MITSuME Akeno Optical Observation
  28. GRB 091208B: Enhanced Swift-XRT position
  29. GRB 091208B: MITSuME Okayama Optical Observation
  30. GRB 091208B, RIMOTS optical upper limits
  31. GRB 091208B: Swift detection of a burst with an optical afterglow
  32. GRB 091208B: BOOTES-3 optical afterglow
  33. Short X-ray Transient, RIMOTS optical upper limits
  34. GRB 091123: Suzaku WAM observation of the prompt emission
  35. GRB 091202: GTC & CAHA optical/nIR afterglow candidate
  36. GRB 091109A: GROND confirmation of redshift z = 3.5
  37. GRB 091127, SMARTS optical/IR afterglow observations
  38. GRB091202: Swift-XRT refined analysis
  39. GRB 091202: Swift/UVOT Upper Limits
  40. GRB 091202: Optical and NIR observations
  41. GRB 091202 - UVOT-enhanced XRT position
  42. GRB 091127: Zadko Telescope Observations
  43. GRB 091126A: Suzaku WAM observation of the prompt emission
  44. GRB 091202: TAROT Calern observatory optical observations
  45. GRB 091117: Chandra Observations
  46. Konus-Wind observation of very long GRB 091123
  47. GRB 091123: Fermi GBM detection of a very long burst
  48. GRB 091126B: Fermi GBM detection
  49. GRB 091127: Suzaku WAM observation of the prompt emission
  50. GRB 091126: Fermi GBM detection
  51. GRB 091130B: Swift-XRT team refined analysis
  52. GRB 091130B: Swift-BAT refined analysis
  53. GRB 091130B: Swift/UVOT Upper Limits
  54. GRB 091127: Skynet/PROMPT Observations of Fading
  55. GRB 091130B: Enhanced Swift-XRT position
  56. Swift trigger 377436 (possible GRB 091130A) is not a burst
  57. GRB 091130B: Swift detection of a burst
  58. GRB 091127: Radio observations
  59. GRB 091128: Fermi GBM detection
  60. GRB 091127: TAROT La Silla observatory optical observations
  61. GRB 091127: LABOCA/APEX submm observations
  62. GRB 091127: Further NOT optical observations
  63. GRB 091127: Fermi GBM detection
  64. GRB 091127: Swift-XRT afterglow detection and analysis
  65. GRB 091127: TAROT La Silla observatory optical decay
  66. GRB 091127: Swift/UVOT observations
  67. GRB 091127: Swift-BAT refined analysis
  68. GRB 091127: NOT observations
  69. GRB 091127 : GROND observations
  70. GRB 091127: REM NIR afterglow detection
  71. GRB 091127: Swift/UVOT Detection of an Optical Afterglow
  72. GRB 091127: Swift detection of a burst
  73. GRB 091120: Fermi GBM observation
  74. GRB 091117A: Suzaku WAM observation of the prompt emission
  75. GRB 091117: TNG optical observations
  76. GRB 091117A: Swift/UVOT followup observations
  77. GRB 091117: VLA radio observations
  78. GRB 091117: Swift-XRT observations
  79. GRB 091117 BAT refined analysis
  80. GRB 091117: Evidence for Variability of XRT Source #1
  81. GRB091117: Gemini South Observations
  82. GRB 091117: Swift XRT refined analysis
  83. GRB 091112: Suzaku WAM observation of the prompt emission
  84. GRB 091102A: Suzaku WAM observation of the prompt emission
  85. GRB 091109B: Suzaku WAM observation of the prompt emission
  86. GRB091111: Swift XRT refined analysis
  87. GRB 091112: Swift-BAT refined analysis
  88. GRB 091031: Fermi LAT detection of a faint burst
  89. GRB 091111: BOOTES-3 contemporaneous imaging
  90. GRB 091111: BOOTES-3 observations
  91. GRB 091109A: GROND and VLT observations
  92. GRB 091109B: Swift/UVOT Upper Limits
  93. GRB 091109B: Swift-XRT Team refined analysis
  94. GRB 091109B: Swift-BAT refined analysis
  95. GRB 091109B: Enhanced Swift-XRT position
  96. GRB 091109B: Optical limits from Watcher
  97. GRB 091109B: ROTSE-III Optical Limits
  98. GRB 091109B: Swift detection of a short burst
  99. GRB 091030: Fermi GBM detection
  100. GRB 091109: Swift-XRT refined analysis

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