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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 061222A: Observation with the KANATA 1.5m telescope
  2. GRB 061222B: BOOTES-IR optical observations
  3. GRB 061222B: SARA upper limit
  4. GRB 061222A: Swift-XRT refined analysis
  5. GRB 061217: Magellan host galaxy redshift
  6. GRB 061222A, Swift-BAT refined analysis
  7. GRB 061222B: REM NIR/optical observations
  8. GRB 061222b: Refined redshift
  9. GRB 061222b, SMARTS optical/IR afterglow observations
  10. GRB 061222B: TAROT La Silla observatory afterglow observation
  11. GRB 061222B: TAROT La Silla observatory optical observations
  12. GRB 061222b: Magellan redshift
  13. GRB 061222B: Swift detection of a burst
  14. GRB 061222b: optical afterglow
  15. GRB 061222A: Prompt ROTSE-III Optical Limits
  16. GRB 061222: Swift detection of a burst
  17. GRB 061217: Astrometry-Corrected XRT Position
  18. GRB 061201: Magellan redshift of nearby galaxy
  19. GRB 061217: Confirmation of host candidate
  20. GRB 061217: Object ib GCN 5948 is a star
  21. GRB 061217: Extended object in the revised XRT error circle
  22. GRB 061217, Candidate host galaxy
  23. GRB 061217 - Swift/XRT position correction
  24. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  25. GRB 061201: Correction to GCN 5944
  26. GRB 061201: Magellan Redshift of nearby Abell cluster
  27. GRB 061218: TAROT La Silla observatory optical observations
  28. GRB 061217: TAROT Calern observatory optical observations
  29. GRB 061218: TORTOREM optical upper limits
  30. GRB 061218, Swift-BAT refined analysis
  31. GRB061217: VLT NIR observations
  32. GRB 061218, SMARTS optical/IR observations
  33. GRB 061218: REM prompt observations
  34. Swift triggers (#251863) on a possible burst
  35. GRB 061217, SMARTS optical observations
  36. GRB061217: Swift/UVOT refined analysis.
  37. GRB 061217: optical observations at Calar Alto
  38. GRB061217 - Swift/XRT refined analysis
  39. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  40. GRB 061217, Swift-BAT refined analysis
  41. GRB 061217: Magellan Observations
  42. GRB 061217: REM prompt observations
  43. GRB 061217: ROTSE-III Optical Limits
  44. GRB 061217: Swift detection of a short hard burst
  45. GRB 061210: MDM Follow-up Observation
  46. GRB061210: Swift/UVOT observations
  47. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  48. GRB 061210: Optical sources near XRT positions
  49. GRB 061210: Swift XRT analysis - Possible counterparts
  50. GRB 061210 : Faulkes North Telescope optical limit
  51. GRB 061214(?): ROTSE-III Optical Limits
  52. GRB 061214(?): Swift detection of a possible burst
  53. GRB 061210: Suzaku WAM observation of the prompt emission
  54. Swift/BAT trigger #250033 is due to a known source during loss of
  55. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  56. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  57. GRB 061213: MASTER-VWF-Kislovodsk observations
  58. GRB 061210: Gemini/GMOS Observations
  59. GRB 061126: Radio Observations
  60. GRB061210: Radio Observations
  61. GRB061201, VLT optical decay: correction
  62. GRB 061126: a GRB detected off-axis by INTEGRAL
  63. GRB 061202: Suzaku WAM observation of the prompt emission
  64. GRB 061210: MDM Observation
  65. GRB 061210, Swift-BAT refined analysis of the SHB
  66. GRB 061210: Swift-BAT detection of a short burst
  67. Optical Afterglow observations of GRB 061126
  68. GRB061126: optical observations
  69. GRB 060926: MASTER: discovery of the optical flare
  70. GRB061126: update on the Swift-XRT afterglow light curve
  71. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  72. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  73. GRB 061202: TORTOREM optical upper limits
  74. GRB 061201: VLT optical decay
  75. GRB 061201: SOAR Confirmation of Candidate Afterglow
  76. GRB061126 : NMSU 1.0m observations
  77. GRB 061202: Swift XRT refined analysis
  78. GRB061202: FRAM early follow-up limit
  79. GRB061202 optical limit by "Pi of the Sky"
  80. Konus-Wind observation of GRB 061201
  81. GRB061202: optical/NIR observations with REM
  82. GRB061202: Swift/UVOT Upper Limits
  83. GRB 061202, Swift-BAT refined analysis
  84. GRB 061202: Swift detection of a burst
  85. GRB 061201: Swift XRT Team refined analysis
  86. GRB 061201: VLT optical observations
  87. GRB 061201: Initial UVOT Observations
  88. GRB 061201, Swift-BAT refined analysis of the SHB
  89. GRB 061201: Swift detection of a short hard burst
  90. GRB 061201: Coincidence with a Galaxy Cluster
  91. GRB 061122: GETS observation
  92. GRB 061121, SMARTS optical/IR observations
  93. GRB 061121: flattening of the decay
  94. INT+WFC observations of GRB 061126
  95. GRB 061126: Possible Jet Break
  96. GRB 061121: Second Epoch ATCA Radio Observations
  97. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  98. Swift XRT on-board boresight update
  99. GRB 061121: ATCA & WSRT Radio Observations
  100. GRB061121: optical observations

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