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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 061110B: NOT optical observations
  2. GRB 061110A: Swift XRT refined analysis
  3. GRB 061110B: Swift/XRT position
  4. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  5. GRB 061110B: Swift-UVOT Initial Observation
  6. GRB 061110A, Swift-BAT refined analysis
  7. GRB 061110B: TAROT Calern observatory optical observations
  8. GRB 061110B: Swift detection of a burst
  9. GRB 061110: NOT observations
  10. GRB 061110: Candidate confirmed
  11. GRB 061110 : Optical afterglow candidate
  12. GRB 061110: ROTSE-III Optical Limits
  13. GRB 061110: Swift detection of a burst
  14. GRB061110A - Optical Non-detection
  15. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  16. GRB 061109: optical observation
  17. GRB 061109: TAROT Calern observatory optical observations
  18. GRB 061109: Swift detection of a possible burst
  19. GRB061028: MAGIC telescope GeV observation
  20. GRB 061027: TAROT La Silla observatory optical observations
  21. GRB 061007: Third Epoch ATCA Radio Observations
  22. GRB061019: second epoch CrAO observations
  23. GRB 061028: Swift/XRT Astrometry Correction
  24. GRB 061102: Swift/UVOT Magnitude Upper Limits
  25. GRB 061102, XRT refined analysis
  26. GRB 061004: Further VLT/NTT observations
  27. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  28. GRB061102B: Super-LOTIS observations
  29. GRB 061028: Optical R passband observations
  30. GRB 061102B: Swift detection of a possible burst
  31. GRB 061102, Swift-BAT refined analysis
  32. GRB 061102: Swift detection of a burst
  33. GRB 061028: VLA Observation
  34. GRB 061004: Swift/XRT Astrometry Correction
  35. GRB 060801: Swift/XRT Astrometry Correction
  36. GRB 061028: Futher P200 Observations
  37. GRB 061028: MDM Observations
  38. GRB 061028: P200 Observations
  39. GRB 061028: SARA upper limit
  40. GRB 061028: z band imaging
  41. GRB061028: XRT refined analysis
  42. GRB 061028: Swift/UVOT Observations
  43. GRB 061028, Swift-BAT refined analysis
  44. GRB 061028: TAROT Calern observatory late optical observations
  45. GRB 061028: TAROT Calern observatory optical observations
  46. GRB 061028: Swift detection of a burst
  47. GRB 061027, Swift refined analysis of a possible burst
  48. GRB 061027: Swift detection of a possible burst
  49. GRB061025: ROTSE-III Confirmation of Optical Counterpart
  50. GRB061025: Swift XRT refined analysis
  51. GRB061025: Swift/UVOT observations
  52. GRB 061019: MITSuME upper limits
  53. GRB 061025: REM observations
  54. GRB 061025: Gemini-S observations
  55. GRB061025: Swift XRT position
  56. GRB 061025: ROTSE-III Optical Limits
  57. GRB 061025: a long GRB detected by INTEGRAL
  58. Swift XRT boresight update
  59. GRB 061021, Swift-BAT Lag analysis
  60. Konus-Wind observation of GRB 061021
  61. GRB 061021 - VLT spectrum without lines
  62. GRB 061021: Swift-XRT refined analysis
  63. GRB 061021: Swift/UVOT Observation
  64. GRB 061021, Swift-BAT refined analysis
  65. GRB 061021: Swift detection of a burst
  66. GRB 061019: Super-LOTIS upper limit
  67. GRB060904b: optical observations
  68. GRB061019: optical observations
  69. GRB061019: optical observations
  70. GRB 061019: SARA upper limit
  71. GRB 061019: dust-scattered X-ray halo detected in Swift/XRT
  72. GRB 060930: MARGE Optical Limits
  73. GRB 061019: Swift/UVOT upper limit
  74. GRB 061019: SMARTS afterglow confirmation
  75. GRB061019: Swift XRT refined analysis
  76. GRB 061019, Swift-BAT refined analysis
  77. GRB 061019: TAROT La Silla observatory optical observations
  78. GRB 061019: REM K-band candidate afterglow
  79. GRB061019: Swift/XRT position
  80. GRB 061019: Swift-BAT detection of a burst
  81. GRB 060825: GORT Observations
  82. GRB 061007: Second Epoch ATCA Radio Observations
  83. GRB 061007: RHESSI Spectral Fit
  84. GRB 061007: Suzaku/WAM observation of the prompt emission
  85. GRB 061006: astrometry-corrected XRT position
  86. Konus-Wind observation of GRB 061007
  87. GRB 060928: Confirmation of the X-ray afterglow detected by Swift
  88. GRB 061007: ATCA Radio Observations
  89. GRB061007: Swift UVOT followup observations
  90. GRB 061006: optical afterglow
  91. GRB 061006 : Suzaku/WAM observation of the prompt emission
  92. GRB 061007: OA fading and VLT redshift
  93. GRB 061007: Magellan Spectroscopy
  94. GRB 061007: Correction to GCN 5712
  95. GRB 061007: Swift-BAT refined analysis
  96. GRB 061007: Swift XRT refined analysis
  97. GRB 061006: Swift/UVOT optical observations
  98. Konus-Wind observation of the short hard GRB 061006
  99. GRB 061007 - FTS early brightening and power law decay
  100. GRB 061007 - Faulkes Telescope South Afterglow Confirmation

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