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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: Astrometry-Corrected XRT Position
  2. GRB 061201: Magellan redshift of nearby galaxy
  3. GRB 061217: Confirmation of host candidate
  4. GRB 061217: Object ib GCN 5948 is a star
  5. GRB 061217: Extended object in the revised XRT error circle
  6. GRB 061217, Candidate host galaxy
  7. GRB 061217 - Swift/XRT position correction
  8. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  9. GRB 061201: Correction to GCN 5944
  10. GRB 061201: Magellan Redshift of nearby Abell cluster
  11. GRB 061218: TAROT La Silla observatory optical observations
  12. GRB 061217: TAROT Calern observatory optical observations
  13. GRB 061218: TORTOREM optical upper limits
  14. GRB 061218, Swift-BAT refined analysis
  15. GRB061217: VLT NIR observations
  16. GRB 061218, SMARTS optical/IR observations
  17. GRB 061218: REM prompt observations
  18. Swift triggers (#251863) on a possible burst
  19. GRB 061217, SMARTS optical observations
  20. GRB061217: Swift/UVOT refined analysis.
  21. GRB 061217: optical observations at Calar Alto
  22. GRB061217 - Swift/XRT refined analysis
  23. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  24. GRB 061217, Swift-BAT refined analysis
  25. GRB 061217: Magellan Observations
  26. GRB 061217: REM prompt observations
  27. GRB 061217: ROTSE-III Optical Limits
  28. GRB 061217: Swift detection of a short hard burst
  29. GRB 061210: MDM Follow-up Observation
  30. GRB061210: Swift/UVOT observations
  31. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  32. GRB 061210: Optical sources near XRT positions
  33. GRB 061210: Swift XRT analysis - Possible counterparts
  34. GRB 061210 : Faulkes North Telescope optical limit
  35. GRB 061214(?): ROTSE-III Optical Limits
  36. GRB 061214(?): Swift detection of a possible burst
  37. GRB 061210: Suzaku WAM observation of the prompt emission
  38. Swift/BAT trigger #250033 is due to a known source during loss of
  39. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  40. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  41. GRB 061213: MASTER-VWF-Kislovodsk observations
  42. GRB 061210: Gemini/GMOS Observations
  43. GRB 061126: Radio Observations
  44. GRB061210: Radio Observations
  45. GRB061201, VLT optical decay: correction
  46. GRB 061126: a GRB detected off-axis by INTEGRAL
  47. GRB 061202: Suzaku WAM observation of the prompt emission
  48. GRB 061210: MDM Observation
  49. GRB 061210, Swift-BAT refined analysis of the SHB
  50. GRB 061210: Swift-BAT detection of a short burst
  51. Optical Afterglow observations of GRB 061126
  52. GRB061126: optical observations
  53. GRB 060926: MASTER: discovery of the optical flare
  54. GRB061126: update on the Swift-XRT afterglow light curve
  55. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  56. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  57. GRB 061202: TORTOREM optical upper limits
  58. GRB 061201: VLT optical decay
  59. GRB 061201: SOAR Confirmation of Candidate Afterglow
  60. GRB061126 : NMSU 1.0m observations
  61. GRB 061202: Swift XRT refined analysis
  62. GRB061202: FRAM early follow-up limit
  63. GRB061202 optical limit by "Pi of the Sky"
  64. Konus-Wind observation of GRB 061201
  65. GRB061202: optical/NIR observations with REM
  66. GRB061202: Swift/UVOT Upper Limits
  67. GRB 061202, Swift-BAT refined analysis
  68. GRB 061202: Swift detection of a burst
  69. GRB 061201: Swift XRT Team refined analysis
  70. GRB 061201: VLT optical observations
  71. GRB 061201: Initial UVOT Observations
  72. GRB 061201, Swift-BAT refined analysis of the SHB
  73. GRB 061201: Swift detection of a short hard burst
  74. GRB 061201: Coincidence with a Galaxy Cluster
  75. GRB 061122: GETS observation
  76. GRB 061121, SMARTS optical/IR observations
  77. GRB 061121: flattening of the decay
  78. INT+WFC observations of GRB 061126
  79. GRB 061126: Possible Jet Break
  80. GRB 061121: Second Epoch ATCA Radio Observations
  81. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  82. Swift XRT on-board boresight update
  83. GRB 061121: ATCA & WSRT Radio Observations
  84. GRB061121: optical observations
  85. GRB 061126: Early Super-LOTIS Observations
  86. GRB 061126: optical observation
  87. RHESSI Spectrum of GRB061126
  88. GRB 061126: Tautenburg afterglow observations
  89. GRB061126: Optical afterglow observations from MIRO
  90. GRB061126: Optical afterglow observations from MIRO
  91. GRB 061126 : SDSS Pre-Burst Observations
  92. GRB 061126: Swift-XRT refined analysis
  93. GRB 061126: Swift/UVOT Observations
  94. GRB 061126, Swift-BAT refined analysis
  95. GRB 061126: SARA Observations
  96. GRB 061126: Early Detection of the IR Afterglow
  97. GRB 061126: Faulkes Telescope North Optical Observations
  98. GRB 061126: Swift/UVOT Afterglow Detection
  99. GRB 061126: XRT position
  100. GRB 061126: Swift detection of a burst

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