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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 061217: TAROT Calern observatory optical observations
  2. GRB 061218: TORTOREM optical upper limits
  3. GRB 061218, Swift-BAT refined analysis
  4. GRB061217: VLT NIR observations
  5. GRB 061218, SMARTS optical/IR observations
  6. GRB 061218: REM prompt observations
  7. Swift triggers (#251863) on a possible burst
  8. GRB 061217, SMARTS optical observations
  9. GRB061217: Swift/UVOT refined analysis.
  10. GRB 061217: optical observations at Calar Alto
  11. GRB061217 - Swift/XRT refined analysis
  12. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  13. GRB 061217, Swift-BAT refined analysis
  14. GRB 061217: Magellan Observations
  15. GRB 061217: REM prompt observations
  16. GRB 061217: ROTSE-III Optical Limits
  17. GRB 061217: Swift detection of a short hard burst
  18. GRB 061210: MDM Follow-up Observation
  19. GRB061210: Swift/UVOT observations
  20. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  21. GRB 061210: Optical sources near XRT positions
  22. GRB 061210: Swift XRT analysis - Possible counterparts
  23. GRB 061210 : Faulkes North Telescope optical limit
  24. GRB 061214(?): ROTSE-III Optical Limits
  25. GRB 061214(?): Swift detection of a possible burst
  26. GRB 061210: Suzaku WAM observation of the prompt emission
  27. Swift/BAT trigger #250033 is due to a known source during loss of
  28. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  29. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  30. GRB 061213: MASTER-VWF-Kislovodsk observations
  31. GRB 061210: Gemini/GMOS Observations
  32. GRB 061126: Radio Observations
  33. GRB061210: Radio Observations
  34. GRB061201, VLT optical decay: correction
  35. GRB 061126: a GRB detected off-axis by INTEGRAL
  36. GRB 061202: Suzaku WAM observation of the prompt emission
  37. GRB 061210: MDM Observation
  38. GRB 061210, Swift-BAT refined analysis of the SHB
  39. GRB 061210: Swift-BAT detection of a short burst
  40. Optical Afterglow observations of GRB 061126
  41. GRB061126: optical observations
  42. GRB 060926: MASTER: discovery of the optical flare
  43. GRB061126: update on the Swift-XRT afterglow light curve
  44. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  45. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  46. GRB 061202: TORTOREM optical upper limits
  47. GRB 061201: VLT optical decay
  48. GRB 061201: SOAR Confirmation of Candidate Afterglow
  49. GRB061126 : NMSU 1.0m observations
  50. GRB 061202: Swift XRT refined analysis
  51. GRB061202: FRAM early follow-up limit
  52. GRB061202 optical limit by "Pi of the Sky"
  53. Konus-Wind observation of GRB 061201
  54. GRB061202: optical/NIR observations with REM
  55. GRB061202: Swift/UVOT Upper Limits
  56. GRB 061202, Swift-BAT refined analysis
  57. GRB 061202: Swift detection of a burst
  58. GRB 061201: Swift XRT Team refined analysis
  59. GRB 061201: VLT optical observations
  60. GRB 061201: Initial UVOT Observations
  61. GRB 061201, Swift-BAT refined analysis of the SHB
  62. GRB 061201: Swift detection of a short hard burst
  63. GRB 061201: Coincidence with a Galaxy Cluster
  64. GRB 061122: GETS observation
  65. GRB 061121, SMARTS optical/IR observations
  66. GRB 061121: flattening of the decay
  67. INT+WFC observations of GRB 061126
  68. GRB 061126: Possible Jet Break
  69. GRB 061121: Second Epoch ATCA Radio Observations
  70. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  71. Swift XRT on-board boresight update
  72. GRB 061121: ATCA & WSRT Radio Observations
  73. GRB061121: optical observations
  74. GRB 061126: Early Super-LOTIS Observations
  75. GRB 061126: optical observation
  76. RHESSI Spectrum of GRB061126
  77. GRB 061126: Tautenburg afterglow observations
  78. GRB061126: Optical afterglow observations from MIRO
  79. GRB061126: Optical afterglow observations from MIRO
  80. GRB 061126 : SDSS Pre-Burst Observations
  81. GRB 061126: Swift-XRT refined analysis
  82. GRB 061126: Swift/UVOT Observations
  83. GRB 061126, Swift-BAT refined analysis
  84. GRB 061126: SARA Observations
  85. GRB 061126: Early Detection of the IR Afterglow
  86. GRB 061126: Faulkes Telescope North Optical Observations
  87. GRB 061126: Swift/UVOT Afterglow Detection
  88. GRB 061126: XRT position
  89. GRB 061126: Swift detection of a burst
  90. GRB 061121: MDM Continued Monitoring
  91. GRB 061122: Confirmation of X-ray/Optical Afterglow
  92. GRB 061121: MDM Continuing Optical Decay
  93. GRB061121: optical observations
  94. GRB 061122: Candidate Optical Afterglow
  95. GRB 061121: Ep,i - Eiso correlation
  96. GRB 061121: MDM Optical Decay
  97. GRB061122: Swift/UVOT Optical Observations
  98. GRB 061121: ART detection in Ic
  99. GRB061121: P60 Observations
  100. Radio detection of GRB 061121

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