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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"

28081 results found.

  1. GRB 061217: Magellan Observations
  2. GRB 061217: REM prompt observations
  3. GRB 061217: ROTSE-III Optical Limits
  4. GRB061210: Swift/UVOT observations
  5. GRB 061210: Swift XRT analysis - Possible counterparts
  6. GRB 061210: Gemini/GMOS Observations
  7. GRB 061126: Radio Observations
  8. GRB061210: Radio Observations
  9. GRB 061202: Suzaku WAM observation of the prompt emission
  10. GRB 061210, Swift-BAT refined analysis of the SHB
  11. Optical Afterglow observations of GRB 061126
  12. GRB 060926: MASTER: discovery of the optical flare
  13. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  14. GRB 061202: TORTOREM optical upper limits
  15. GRB 061201: VLT optical decay
  16. GRB 061201: SOAR Confirmation of Candidate Afterglow
  17. GRB061202: FRAM early follow-up limit
  18. GRB061202 optical limit by "Pi of the Sky"
  19. GRB061202: optical/NIR observations with REM
  20. GRB061202: Swift/UVOT Upper Limits
  21. GRB 061202, Swift-BAT refined analysis
  22. GRB 061202: Swift detection of a burst
  23. GRB 061201: VLT optical observations
  24. GRB 061201: Initial UVOT Observations
  25. GRB 061201, Swift-BAT refined analysis of the SHB
  26. GRB 061201: Swift detection of a short hard burst
  27. INT+WFC observations of GRB 061126
  28. Swift XRT on-board boresight update
  29. GRB 061126: optical observation
  30. GRB 061126: Tautenburg afterglow observations
  31. GRB061126: Optical afterglow observations from MIRO
  32. GRB061126: Optical afterglow observations from MIRO
  33. GRB 061126 : SDSS Pre-Burst Observations
  34. GRB 061126: Swift-XRT refined analysis
  35. GRB 061126: Swift/UVOT Observations
  36. GRB 061126, Swift-BAT refined analysis
  37. GRB 061126: Early Detection of the IR Afterglow
  38. GRB 061126: Swift/UVOT Afterglow Detection
  39. GRB 061122: Candidate Optical Afterglow
  40. GRB 061121: Ep,i - Eiso correlation
  41. GRB061122: Swift/UVOT Optical Observations
  42. GRB061121: P60 Observations
  43. Radio detection of GRB 061121
  44. GRB061122: Swift-XRT position
  45. INTEGRAL results on GRB 061122
  46. Swift-BAT trigger 239987 is not a GRB
  47. GRB 061121: Swift/UVOT Observations
  48. GRB 061121: Swift-XRT Team Refined Analysis
  49. GRB 061121, Swift-BAT refined analysis
  50. GRB061121, optical observation
  51. GRB 061121: Optical observation at the KANATA 1.5m telescope
  52. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  53. GRB 061121: Swift detection of a bright burst with an optical counterpart
  54. GRB 060605: NIR Observations
  55. GRB 050915B: optical afterglow
  56. Swift-BAT triggers 238544 and 238546 are not GRBs
  57. Swift/UVOT Upper Limits for GRB061110b
  58. Swift/UVOT Upper Limits for GRB061110a
  59. GRB 061110B, Swift-BAT refined analysis
  60. GRB061110B: Optical observations at Crni Vrh
  61. GRB 061110A: Swift XRT refined analysis
  62. GRB 061110A, Swift-BAT refined analysis
  63. GRB 061110B: TAROT Calern observatory optical observations
  64. GRB 061110B: Swift detection of a burst
  65. GRB 061110: Candidate confirmed
  66. GRB 061110 : Optical afterglow candidate
  67. GRB 061110: ROTSE-III Optical Limits
  68. GRB 061110: Swift detection of a burst
  69. GRB061110A - Optical Non-detection
  70. GRB 061109: optical observation
  71. GRB 061109: TAROT Calern observatory optical observations
  72. GRB 061027: TAROT La Silla observatory optical observations
  73. GRB 061028: Swift/XRT Astrometry Correction
  74. GRB 061102: Swift/UVOT Magnitude Upper Limits
  75. GRB 061102, XRT refined analysis
  76. GRB061102B: Super-LOTIS observations
  77. GRB 061028: Optical R passband observations
  78. GRB 061102B: Swift detection of a possible burst
  79. GRB 061102, Swift-BAT refined analysis
  80. GRB 061102: Swift detection of a burst
  81. GRB 061028: VLA Observation
  82. GRB 061004: Swift/XRT Astrometry Correction
  83. GRB 060801: Swift/XRT Astrometry Correction
  84. GRB 061028: Futher P200 Observations
  85. GRB 061028: P200 Observations
  86. GRB 061028: SARA upper limit
  87. GRB 061028: z band imaging
  88. GRB061028: XRT refined analysis
  89. GRB 061028: Swift/UVOT Observations
  90. GRB 061028, Swift-BAT refined analysis
  91. GRB 061028: TAROT Calern observatory optical observations
  92. GRB 061028: Swift detection of a burst
  93. GRB 061027, Swift refined analysis of a possible burst
  94. GRB 061027: Swift detection of a possible burst
  95. GRB061025: Swift XRT refined analysis
  96. GRB061025: Swift/UVOT observations
  97. GRB 061025: REM observations
  98. GRB 061025: ROTSE-III Optical Limits
  99. GRB 061025: a long GRB detected by INTEGRAL
  100. Swift XRT boresight update

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