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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"
  1. GRB 091221, GROND observations
  2. GRB 091221: UVOT Confirmation of an Optical Afterglow
  3. GRB 091221: ROTSE-III Detection of Optical Counterpart
  4. GRB 091221: Swift detection of a burst
  5. Swift trigger 379449 (possible GRB) is not a burst
  6. GRB 091215: Faulkes Telescope North observations
  7. Trigger 379449: Swift detection of a possible burst
  8. GRB 091208B: Xinglong TNT optical observation
  9. GRB 091208A: Suzaku WAM observation of the prompt emission
  10. GRB 091208A: GAO 150cm telescope Optical Observation
  11. Konus-Wind observation of GRB 091208A
  12. GRB 091208B: GAO 150cm telescope Optical Observation
  13. GRB091208A: Swift/UVOT refined analysis
  14. GRB 091208B: optical observations
  15. GRB 091208B: Keck HIRES redshift confirmation
  16. GRB 091208B: GROND observations
  17. GRB 091208A: Swift-XRT observations
  18. GRB091208B: NOT optical observations
  19. GRB 091208B: Swift-XRT refined analysis
  20. GRB091208B: Swift/UVOT refined analysis
  21. GRB 091208B: Fermi GBM observation
  22. GRB 091208B, Swift-BAT refined analysis
  23. GRB 091208A Swift-BAT refined analysis
  24. GRB 091208B: Gemini-North redshift
  25. GRB 091208B: Faulkes Telescope North and South Optical Afterglow
  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. GRB 091208: ROTSE-III Optical Limits
  34. GRB 091208: Swift detection of a burst
  35. Short X-ray Transient, RIMOTS optical upper limits
  36. A small revision to the GRB-naming convention
  37. GRB 091123: Suzaku WAM observation of the prompt emission
  38. GRB 091127: Skynet/PROMPT Observations of Possible Host Galaxy
  39. GRB 091127: GAO 150cm telescope Optical Observation
  40. GRB 091202: GTC & CAHA optical/nIR afterglow candidate
  41. GRB 091109A: GROND confirmation of redshift z = 3.5
  42. GRB091127: Continuing Swift/UVOT Observations
  43. GRB 091127, SMARTS optical/IR afterglow observations
  44. GRB091202: Swift-XRT refined analysis
  45. GRB 091202: Swift/UVOT Upper Limits
  46. GRB 091202: Liverpool Telescope observations
  47. GRB 091202: Optical and NIR observations
  48. GRB 091202 - UVOT-enhanced XRT position
  49. GRB 091127: Zadko Telescope Observations
  50. GRB 091126A: Suzaku WAM observation of the prompt emission
  51. GRB 091202: TAROT Calern observatory optical observations
  52. GRB 091202: Liverpool Telescope Observations
  53. GRB 091202: a long GRB detected by INTEGRAL
  54. GRB 091127: redshift confirmation with X-shooter
  55. GRB 091117: Chandra Observations
  56. GRB 091020: MASTER-Net optical polarization observations
  57. GRB 091127: Skynet/PROMPT Continued Observations of Fading
  58. Short X-ray Transient Detection by MAXI/GSC
  59. Konus-Wind observation of very long GRB 091123
  60. GRB 091130A: Xinglong TNT upper limit
  61. GRB 091123: Fermi GBM detection of a very long burst
  62. GRB 091126B: Fermi GBM detection
  63. GRB 091127: Suzaku WAM observation of the prompt emission
  64. GRB 091126: Fermi GBM detection
  65. GRB 091130B: Swift-XRT team refined analysis
  66. GRB 091130B: Swift-BAT refined analysis
  67. GRB 091130B: Swift/UVOT Upper Limits
  68. GRB 091127: Skynet/PROMPT Observations of Fading
  69. GRB 091130B: Enhanced Swift-XRT position
  70. Swift trigger 377436 (possible GRB 091130A) is not a burst
  71. GRB 091130B: MASTER observations
  72. GRB 091130B: SDSS galaxy at XRT location
  73. GRB 091130B: Swift detection of a burst
  74. GRB 091130: MASTER observations
  75. GRB 091130: Swift detection of a possible burst
  76. GRB 091127: Radio observations
  77. GRB 091128: Fermi GBM detection
  78. Konus-Wind observation of GRB 091127
  79. GRB 091127: TAROT La Silla observatory optical observations
  80. GRB 091127: optical observations
  81. GRB 091127: LABOCA/APEX submm observations
  82. GRB 091127: Further NOT optical observations
  83. GRB 091127: Fermi GBM detection
  84. GRB 091127: MASTER early optical transient polarimetry
  85. GRB 091127: Gemini-N redshift
  86. GRB 091127: Swift-XRT afterglow detection and analysis
  87. GRB 091127: TAROT La Silla observatory optical decay
  88. GRB 091127: Swift/UVOT observations
  89. GRB 091127: CAHA 1.23m I-band observations
  90. GRB 091127: Swift-BAT refined analysis
  91. GRB 091127: NOT observations
  92. GRB 091127 : GROND observations
  93. GRB 091127: REM NIR afterglow detection
  94. GRB 091127: Swift/UVOT Detection of an Optical Afterglow
  95. GRB 091127: Liverpool Telescope afterglow candidate
  96. GRB 091127: Swift detection of a burst
  97. IPN Triangulation of GRB091120
  98. Konus-Wind observation of GRB 091120
  99. GRB 091120: MAXI GSC detection
  100. GRB 091120: Fermi GBM observation

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