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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 061201: Correction to GCN 5944
  2. GRB 061201: Magellan Redshift of nearby Abell cluster
  3. GRB 061218: TAROT La Silla observatory optical observations
  4. GRB 061217: TAROT Calern observatory optical observations
  5. GRB 061218: TORTOREM optical upper limits
  6. GRB 061218, Swift-BAT refined analysis
  7. GRB061217: VLT NIR observations
  8. GRB 061218, SMARTS optical/IR observations
  9. GRB 061218: REM prompt observations
  10. Swift triggers (#251863) on a possible burst
  11. GRB 061217, SMARTS optical observations
  12. GRB061217: Swift/UVOT refined analysis.
  13. GRB 061217: optical observations at Calar Alto
  14. GRB061217 - Swift/XRT refined analysis
  15. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  16. GRB 061217, Swift-BAT refined analysis
  17. GRB 061217: Magellan Observations
  18. GRB 061217: REM prompt observations
  19. GRB 061217: ROTSE-III Optical Limits
  20. GRB 061217: Swift detection of a short hard burst
  21. GRB 061210: MDM Follow-up Observation
  22. GRB061210: Swift/UVOT observations
  23. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  24. GRB 061210: Optical sources near XRT positions
  25. GRB 061210: Swift XRT analysis - Possible counterparts
  26. GRB 061210 : Faulkes North Telescope optical limit
  27. GRB 061214(?): ROTSE-III Optical Limits
  28. GRB 061214(?): Swift detection of a possible burst
  29. GRB 061210: Suzaku WAM observation of the prompt emission
  30. Swift/BAT trigger #250033 is due to a known source during loss of
  31. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  32. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  33. GRB 061213: MASTER-VWF-Kislovodsk observations
  34. GRB 061210: Gemini/GMOS Observations
  35. GRB 061126: Radio Observations
  36. GRB061210: Radio Observations
  37. GRB061201, VLT optical decay: correction
  38. GRB 061126: a GRB detected off-axis by INTEGRAL
  39. GRB 061202: Suzaku WAM observation of the prompt emission
  40. GRB 061210: MDM Observation
  41. GRB 061210, Swift-BAT refined analysis of the SHB
  42. GRB 061210: Swift-BAT detection of a short burst
  43. Optical Afterglow observations of GRB 061126
  44. GRB061126: optical observations
  45. GRB 060926: MASTER: discovery of the optical flare
  46. GRB061126: update on the Swift-XRT afterglow light curve
  47. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  48. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  49. GRB 061202: TORTOREM optical upper limits
  50. GRB 061201: VLT optical decay
  51. GRB 061201: SOAR Confirmation of Candidate Afterglow
  52. GRB061126 : NMSU 1.0m observations
  53. GRB 061202: Swift XRT refined analysis
  54. GRB061202: FRAM early follow-up limit
  55. GRB061202 optical limit by "Pi of the Sky"
  56. Konus-Wind observation of GRB 061201
  57. GRB061202: optical/NIR observations with REM
  58. GRB061202: Swift/UVOT Upper Limits
  59. GRB 061202, Swift-BAT refined analysis
  60. GRB 061202: Swift detection of a burst
  61. GRB 061201: Swift XRT Team refined analysis
  62. GRB 061201: VLT optical observations
  63. GRB 061201: Initial UVOT Observations
  64. GRB 061201, Swift-BAT refined analysis of the SHB
  65. GRB 061201: Swift detection of a short hard burst
  66. GRB 061201: Coincidence with a Galaxy Cluster
  67. GRB 061122: GETS observation
  68. GRB 061121, SMARTS optical/IR observations
  69. GRB 061121: flattening of the decay
  70. INT+WFC observations of GRB 061126
  71. GRB 061126: Possible Jet Break
  72. GRB 061121: Second Epoch ATCA Radio Observations
  73. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  74. Swift XRT on-board boresight update
  75. GRB 061121: ATCA & WSRT Radio Observations
  76. GRB061121: optical observations
  77. GRB 061126: Early Super-LOTIS Observations
  78. GRB 061126: optical observation
  79. RHESSI Spectrum of GRB061126
  80. GRB 061126: Tautenburg afterglow observations
  81. GRB061126: Optical afterglow observations from MIRO
  82. GRB061126: Optical afterglow observations from MIRO
  83. GRB 061126 : SDSS Pre-Burst Observations
  84. GRB 061126: Swift-XRT refined analysis
  85. GRB 061126: Swift/UVOT Observations
  86. GRB 061126, Swift-BAT refined analysis
  87. GRB 061126: SARA Observations
  88. GRB 061126: Early Detection of the IR Afterglow
  89. GRB 061126: Faulkes Telescope North Optical Observations
  90. GRB 061126: Swift/UVOT Afterglow Detection
  91. GRB 061126: XRT position
  92. GRB 061126: Swift detection of a burst
  93. GRB 061121: MDM Continued Monitoring
  94. GRB 061122: Confirmation of X-ray/Optical Afterglow
  95. GRB 061121: MDM Continuing Optical Decay
  96. GRB061121: optical observations
  97. GRB 061122: Candidate Optical Afterglow
  98. GRB 061121: Ep,i - Eiso correlation
  99. GRB 061121: MDM Optical Decay
  100. GRB061122: Swift/UVOT Optical Observations

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