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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"

19595 results found.

  1. GRB 061210: MDM Observation
  2. GRB 061210, Swift-BAT refined analysis of the SHB
  3. GRB 061210: Swift-BAT detection of a short burst
  4. Optical Afterglow observations of GRB 061126
  5. GRB061126: update on the Swift-XRT afterglow light curve
  6. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  7. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  8. GRB061126 : NMSU 1.0m observations
  9. GRB 061202: Swift XRT refined analysis
  10. GRB061202: FRAM early follow-up limit
  11. GRB061202 optical limit by "Pi of the Sky"
  12. Konus-Wind observation of GRB 061201
  13. GRB061202: Swift/UVOT Upper Limits
  14. GRB 061202, Swift-BAT refined analysis
  15. GRB 061202: Swift detection of a burst
  16. GRB 061201: Swift XRT Team refined analysis
  17. GRB 061201: Initial UVOT Observations
  18. GRB 061201, Swift-BAT refined analysis of the SHB
  19. GRB 061201: Swift detection of a short hard burst
  20. GRB 061201: Coincidence with a Galaxy Cluster
  21. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  22. Swift XRT on-board boresight update
  23. GRB 061126: Early Super-LOTIS Observations
  24. GRB061126: Optical afterglow observations from MIRO
  25. GRB061126: Optical afterglow observations from MIRO
  26. GRB 061126: Swift-XRT refined analysis
  27. GRB 061126: Swift/UVOT Observations
  28. GRB 061126, Swift-BAT refined analysis
  29. GRB 061126: Faulkes Telescope North Optical Observations
  30. GRB 061126: Swift/UVOT Afterglow Detection
  31. GRB 061126: XRT position
  32. GRB 061126: Swift detection of a burst
  33. GRB 061122: Confirmation of X-ray/Optical Afterglow
  34. GRB 061122: Candidate Optical Afterglow
  35. GRB 061121: Ep,i - Eiso correlation
  36. GRB061122: Swift/UVOT Optical Observations
  37. GRB061122: Swift-XRT position
  38. GRB 061121 declared "Burst of Interest" by Swift team
  39. Konus-Wind and Konus-A observations of GRB 061121
  40. Swift-BAT trigger 239987 is not a GRB
  41. GRB 061121: Swift/UVOT Observations
  42. GRB 061121: Swift-XRT Team Refined Analysis
  43. GRB 061121, Swift-BAT refined analysis
  44. GRB061121, optical observation
  45. GRB 061121: Faulkes Telescope North Optical Observation
  46. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  47. GRB 061121: Swift detection of a bright burst with an optical counterpart
  48. GRB 060111B: Swift UVOT Refined Magnitudes
  49. Swift-BAT triggers 238544 and 238546 are not GRBs
  50. Swift TOO observations of GRB061110A
  51. Swift/UVOT Upper Limits for GRB061110b
  52. Swift/UVOT Upper Limits for GRB061110a
  53. GRB 061110B: Swift XRT refined analysis
  54. GRB 061110B, Swift-BAT refined analysis
  55. GRB061110B: Optical observations at Crni Vrh
  56. GRB 061110A: Swift XRT refined analysis
  57. GRB 061110B: Swift/XRT position
  58. GRB 061110B: Swift-UVOT Initial Observation
  59. GRB 061110A, Swift-BAT refined analysis
  60. GRB 061110B: TAROT Calern observatory optical observations
  61. GRB 061110B: Swift detection of a burst
  62. GRB 061110: ROTSE-III Optical Limits
  63. GRB 061110: Swift detection of a burst
  64. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  65. GRB 061109: TAROT Calern observatory optical observations
  66. GRB 061109: Swift detection of a possible burst
  67. GRB061028: MAGIC telescope GeV observation
  68. GRB 061027: TAROT La Silla observatory optical observations
  69. GRB 061028: Swift/XRT Astrometry Correction
  70. GRB 061102: Swift/UVOT Magnitude Upper Limits
  71. GRB 061102, XRT refined analysis
  72. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  73. GRB061102B: Super-LOTIS observations
  74. GRB 061028: Optical R passband observations
  75. GRB 061102B: Swift detection of a possible burst
  76. GRB 061102, Swift-BAT refined analysis
  77. GRB 061102: Swift detection of a burst
  78. GRB 061028: VLA Observation
  79. GRB 061004: Swift/XRT Astrometry Correction
  80. GRB 060801: Swift/XRT Astrometry Correction
  81. GRB 061028: MDM Observations
  82. GRB 061028: SARA upper limit
  83. GRB061028: XRT refined analysis
  84. GRB 061028: Swift/UVOT Observations
  85. GRB 061028, Swift-BAT refined analysis
  86. GRB 061028: TAROT Calern observatory optical observations
  87. GRB 061028: Swift detection of a burst
  88. GRB 061027, Swift refined analysis of a possible burst
  89. GRB 061027: Swift detection of a possible burst
  90. GRB061025: Swift XRT refined analysis
  91. GRB061025: Swift/UVOT observations
  92. GRB061025: Swift XRT position
  93. Swift XRT boresight update
  94. GRB 061021, Swift-BAT Lag analysis
  95. Konus-Wind observation of GRB 061021
  96. GRB 061021: Swift-XRT refined analysis
  97. GRB 061021: Swift/UVOT Observation
  98. GRB 061021, Swift-BAT refined analysis
  99. GRB 061021: Swift detection of a burst
  100. GRB 061019: Super-LOTIS upper limit

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