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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 060605: NIR Observations
  2. GRB 050915B: optical afterglow
  3. GRB 060111B: Swift UVOT Refined Magnitudes
  4. Swift-BAT triggers 238544 and 238546 are not GRBs
  5. GRB061110A: Correction to GCN5817
  6. GRB 061110A: refined R-band analysis
  7. GRB 061110B: NIR Observations
  8. Swift TOO observations of GRB061110A
  9. Swift/UVOT Upper Limits for GRB061110b
  10. Swift/UVOT Upper Limits for GRB061110a
  11. GRB 061110A - VLT tentative redshift
  12. GRB 061110B: Swift XRT refined analysis
  13. GRB 061110B, Swift-BAT refined analysis
  14. GRB 061110B: VLT redshift
  15. GRB061110B: Optical observations at Crni Vrh
  16. GRB 061110B: NOT optical observations
  17. GRB 061110A: Swift XRT refined analysis
  18. GRB 061110B: Swift/XRT position
  19. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  20. GRB 061110B: Swift-UVOT Initial Observation
  21. GRB 061110A, Swift-BAT refined analysis
  22. GRB 061110B: TAROT Calern observatory optical observations
  23. GRB 061110B: Swift detection of a burst
  24. GRB 061110: NOT observations
  25. GRB 061110: Candidate confirmed
  26. GRB 061110 : Optical afterglow candidate
  27. GRB 061110: ROTSE-III Optical Limits
  28. GRB 061110: Swift detection of a burst
  29. GRB061110A - Optical Non-detection
  30. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  31. GRB 061109: optical observation
  32. GRB 061109: TAROT Calern observatory optical observations
  33. GRB 061109: Swift detection of a possible burst
  34. GRB061028: MAGIC telescope GeV observation
  35. GRB 061027: TAROT La Silla observatory optical observations
  36. GRB 061007: Third Epoch ATCA Radio Observations
  37. GRB061019: second epoch CrAO observations
  38. GRB 061028: Swift/XRT Astrometry Correction
  39. GRB 061102: Swift/UVOT Magnitude Upper Limits
  40. GRB 061102, XRT refined analysis
  41. GRB 061004: Further VLT/NTT observations
  42. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  43. GRB061102B: Super-LOTIS observations
  44. GRB 061028: Optical R passband observations
  45. GRB 061102B: Swift detection of a possible burst
  46. GRB 061102, Swift-BAT refined analysis
  47. GRB 061102: Swift detection of a burst
  48. GRB 061028: VLA Observation
  49. GRB 061004: Swift/XRT Astrometry Correction
  50. GRB 060801: Swift/XRT Astrometry Correction
  51. GRB 061028: Futher P200 Observations
  52. GRB 061028: MDM Observations
  53. GRB 061028: P200 Observations
  54. GRB 061028: SARA upper limit
  55. GRB 061028: z band imaging
  56. GRB061028: XRT refined analysis
  57. GRB 061028: Swift/UVOT Observations
  58. GRB 061028, Swift-BAT refined analysis
  59. GRB 061028: TAROT Calern observatory late optical observations
  60. GRB 061028: TAROT Calern observatory optical observations
  61. GRB 061028: Swift detection of a burst
  62. GRB 061027, Swift refined analysis of a possible burst
  63. GRB 061027: Swift detection of a possible burst
  64. GRB061025: ROTSE-III Confirmation of Optical Counterpart
  65. GRB061025: Swift XRT refined analysis
  66. GRB061025: Swift/UVOT observations
  67. GRB 061019: MITSuME upper limits
  68. GRB 061025: REM observations
  69. GRB 061025: Gemini-S observations
  70. GRB061025: Swift XRT position
  71. GRB 061025: ROTSE-III Optical Limits
  72. GRB 061025: a long GRB detected by INTEGRAL
  73. Swift XRT boresight update
  74. GRB 061021, Swift-BAT Lag analysis
  75. Konus-Wind observation of GRB 061021
  76. GRB 061021 - VLT spectrum without lines
  77. GRB 061021: Swift-XRT refined analysis
  78. GRB 061021: Swift/UVOT Observation
  79. GRB 061021, Swift-BAT refined analysis
  80. GRB 061021: Swift detection of a burst
  81. GRB 061019: Super-LOTIS upper limit
  82. GRB060904b: optical observations
  83. GRB061019: optical observations
  84. GRB061019: optical observations
  85. GRB 061019: SARA upper limit
  86. GRB 061019: dust-scattered X-ray halo detected in Swift/XRT
  87. GRB 060930: MARGE Optical Limits
  88. GRB 061019: Swift/UVOT upper limit
  89. GRB 061019: SMARTS afterglow confirmation
  90. GRB061019: Swift XRT refined analysis
  91. GRB 061019, Swift-BAT refined analysis
  92. GRB 061019: TAROT La Silla observatory optical observations
  93. GRB 061019: REM K-band candidate afterglow
  94. GRB061019: Swift/XRT position
  95. GRB 061019: Swift-BAT detection of a burst
  96. GRB 060825: GORT Observations
  97. GRB 061007: Second Epoch ATCA Radio Observations
  98. GRB 061007: RHESSI Spectral Fit
  99. GRB 061007: Suzaku/WAM observation of the prompt emission
  100. GRB 061006: astrometry-corrected XRT position

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