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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 061109: Swift detection of a possible burst
  2. GRB061028: MAGIC telescope GeV observation
  3. GRB 061027: TAROT La Silla observatory optical observations
  4. GRB 061007: Third Epoch ATCA Radio Observations
  5. GRB061019: second epoch CrAO observations
  6. GRB 061028: Swift/XRT Astrometry Correction
  7. GRB 061102: Swift/UVOT Magnitude Upper Limits
  8. GRB 061102, XRT refined analysis
  9. GRB 061004: Further VLT/NTT observations
  10. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  11. GRB061102B: Super-LOTIS observations
  12. GRB 061028: Optical R passband observations
  13. GRB 061102B: Swift detection of a possible burst
  14. GRB 061102, Swift-BAT refined analysis
  15. GRB 061102: Swift detection of a burst
  16. GRB 061028: VLA Observation
  17. GRB 061004: Swift/XRT Astrometry Correction
  18. GRB 060801: Swift/XRT Astrometry Correction
  19. GRB 061028: Futher P200 Observations
  20. GRB 061028: MDM Observations
  21. GRB 061028: P200 Observations
  22. GRB 061028: SARA upper limit
  23. GRB 061028: z band imaging
  24. GRB061028: XRT refined analysis
  25. GRB 061028: Swift/UVOT Observations
  26. GRB 061028, Swift-BAT refined analysis
  27. GRB 061028: TAROT Calern observatory late optical observations
  28. GRB 061028: TAROT Calern observatory optical observations
  29. GRB 061028: Swift detection of a burst
  30. GRB 061027, Swift refined analysis of a possible burst
  31. GRB 061027: Swift detection of a possible burst
  32. GRB061025: ROTSE-III Confirmation of Optical Counterpart
  33. GRB061025: Swift XRT refined analysis
  34. GRB061025: Swift/UVOT observations
  35. GRB 061019: MITSuME upper limits
  36. GRB 061025: REM observations
  37. GRB 061025: Gemini-S observations
  38. GRB061025: Swift XRT position
  39. GRB 061025: ROTSE-III Optical Limits
  40. GRB 061025: a long GRB detected by INTEGRAL
  41. Swift XRT boresight update
  42. GRB 061021, Swift-BAT Lag analysis
  43. Konus-Wind observation of GRB 061021
  44. GRB 061021 - VLT spectrum without lines
  45. GRB 061021: Swift-XRT refined analysis
  46. GRB 061021: Swift/UVOT Observation
  47. GRB 061021, Swift-BAT refined analysis
  48. GRB 061021: Swift detection of a burst
  49. GRB 061019: Super-LOTIS upper limit
  50. GRB060904b: optical observations
  51. GRB061019: optical observations
  52. GRB061019: optical observations
  53. GRB 061019: SARA upper limit
  54. GRB 061019: dust-scattered X-ray halo detected in Swift/XRT
  55. GRB 060930: MARGE Optical Limits
  56. GRB 061019: Swift/UVOT upper limit
  57. GRB 061019: SMARTS afterglow confirmation
  58. GRB061019: Swift XRT refined analysis
  59. GRB 061019, Swift-BAT refined analysis
  60. GRB 061019: TAROT La Silla observatory optical observations
  61. GRB 061019: REM K-band candidate afterglow
  62. GRB061019: Swift/XRT position
  63. GRB 061019: Swift-BAT detection of a burst
  64. GRB 060825: GORT Observations
  65. GRB 061007: Second Epoch ATCA Radio Observations
  66. GRB 061007: RHESSI Spectral Fit
  67. GRB 061007: Suzaku/WAM observation of the prompt emission
  68. GRB 061006: astrometry-corrected XRT position
  69. Konus-Wind observation of GRB 061007
  70. GRB 060928: Confirmation of the X-ray afterglow detected by Swift
  71. GRB 061007: ATCA Radio Observations
  72. GRB061007: Swift UVOT followup observations
  73. GRB 061006: optical afterglow
  74. GRB 061006 : Suzaku/WAM observation of the prompt emission
  75. GRB 061007: OA fading and VLT redshift
  76. GRB 061007: Magellan Spectroscopy
  77. GRB 061007: Correction to GCN 5712
  78. GRB 061007: Swift-BAT refined analysis
  79. GRB 061007: Swift XRT refined analysis
  80. GRB 061006: Swift/UVOT optical observations
  81. Konus-Wind observation of the short hard GRB 061006
  82. GRB 061007 - FTS early brightening and power law decay
  83. GRB 061007 - Faulkes Telescope South Afterglow Confirmation
  84. GRB 061007: Swift detection of a burst with an optical counterpart
  85. GRB 061007: ROTSE-III Detection of Optical Counterpart
  86. GRB 061006: VLT observation
  87. GRB 061006: Swift-BAT refined analysis of the short-hard burst
  88. GRB 061006: Swift-XRT Team Refined Analysis
  89. GRB061006 (Swift 232585) might be a short-hard GRB
  90. GRB 060930: near-IR afterglow candidate retraction
  91. GRB061006: Faulkes Telescope South Observations
  92. GRB 061006: Swift detection of a burst
  93. GRB 061004: Optical afterglow candidate and redshift
  94. GRB 061004: Las Campanas Optical/NIR Observations
  95. GRB061004: Swift/UVOT optical observations
  96. GRB 061004: Swift-XRT Team Refined Analysis
  97. GRB 061004, Swift BAT refined analysis
  98. GRB 061004: Nearby 2MASS Galaxy
  99. GRB 060928: Correction to GCN 5690
  100. GRB 061004: Swift detection of a burst

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