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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 051221: IR Observations at GRB+1hr
  2. GRB 051221: Swift detection of a bright short burst
  3. Refined analysis of the SWIFT J1626.6-5156
  4. Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156
  5. Refined analysis of the Swift-BAT detection of the RS CVn star II Peg
  6. GRB051211A (=H3979): Refined Analysis
  7. GRB 051211B: optical afterglow
  8. Swift detection of an RS CVn flare star
  9. GRB051211A: possible optical candidate
  10. Swift Trigger 172767 is not a GRB
  11. GRB 051215: near-infrared observations
  12. GRB051215 - SDSS pre-burst observations
  13. GRB 051215: Swift detection of a possible burst
  14. GRB 051215: A short GRB in a cluster?
  15. GRB051211B: Probable radio afterglow
  16. GRB051105: optical observations
  17. GRB 051213: Swift-BAT refined analysis
  18. GRB051211B: XRT refined analysis
  19. GRB 051211B, optical observation
  20. GRB 051213: Swift-BAT detection of a burst
  21. GRB 051211a: RTT150 optical observations
  22. GRB051211B, RBO optical observations
  23. GRB 051211A: Swift/UVOT upper limits
  24. GRB 051211B: Swift/UVOT upper limits - correction
  25. GRB 051211B: Swift/UVOT upper limits
  26. GRB 051211A,optical observation
  27. GRB 051211B: Swift XRT confirmation of the afterglow
  28. GRB051211B: Liverpool Telescope observation
  29. GRB 051211b: RTT150 optical observations
  30. GRB051211b: P60 Observations
  31. GRB 051211A and GRB051211B: BOOTES simultaneous observations
  32. GRB 051211B: Swift XRT Observations
  33. GRB 051210: Swift/UVOT upper limits
  34. GRB 051210: Magellan Imaging
  35. GRB 051211: TAROT optical limits
  36. GRB 051211B: a possible optical detection by TAROT
  37. GRB 051211B: a long GRB detected by INTEGRAL
  38. GRB 051211: Swift XRT upper limit
  39. GRB 051211:IAC80 optical observations
  40. HETE SXC localization of GRB 051211 (=H3979)
  41. GRB 051210: Optical imaging from Las Campanas
  42. GRB 051210: SALT detection limit
  43. GRB 051210: BAT further refined analysis of the short burst
  44. GRB 051210: Swift XRT refined analysis
  45. GRB 051210: FRAM early limit
  46. GRB 051210: Swift-BAT refined analysis of a short burst
  47. GRB051210: Swift UVOT Observation
  48. GRB 051210: A short GRB in a cluster?
  49. GRB 051210: Swift detection of a burst
  50. IPN observations of SGR1806-20
  51. Swift XRT positions
  52. An extraordinary long burst on December 3 from SGR1806-20
  53. IBAS Alert 2706 : not a real GRB
  54. Possible resuming of the SGR 1806-20 activity
  55. Swift UVOT Calibration Documentation
  56. GRB051117B: optical observation
  57. GRB051111: optical observaion
  58. Swift-BAT trigger 165579 is not a GRB
  59. GRB 051127: Swift-BAT detection of a possible burst
  60. GRB051117B: Swift XRT refined analysis
  61. GRB051117b: No Swift/UVOT Detection
  62. GRB051111: Rc optical observations: correction
  63. GRB 051117A: Swift/UVOT Detection of an Afterglow: Correction
  64. GRB 051117A: Swift/UVOT Detection of an Afterglow
  65. GRB051111: Suzaku WAM observation of the prompt emission
  66. GRB051111: Rc optical observations
  67. GRB051008: Suzaku WAM observation of the prompt emission
  68. GRB 051109B: GAO 150cm telescope Optical limit
  69. GRB 051109A : GAO 150cm telescope Rc-band detection
  70. GRB 051021 Optical Observations
  71. GRB 051117B: MARGE Optical Limits
  72. GRB 051117A and B: Radio Observations
  73. GRB 051117B: R and I observations of possible host galaxy
  74. GRB 051117b: NIR observations
  75. GRB 051117A: Refined analysis of the Swift-BAT burst
  76. GRB 051117B: Refined analysis of the Swift-BAT burst
  77. GRB051117A : XRT refined analysis
  78. GRB 051117B,optical observation
  79. GRB 051117B: Lulin R and I band observation
  80. GRB 051117B: Optical observations
  81. GRB 051117B: ROTSE-III Optical Limits
  82. GRB051117B: Swift XRT position
  83. GRB 051117B: Swift detection of a burst
  84. GRB 051117: Swift detection of a bright burst
  85. GRB051114: results of the Swift-XRT observation
  86. GRB 051028 Optical Observations
  87. GRB 051109B : Nainital upper limits
  88. GRB 051114: Radio Observations
  89. GRB 051114: Swift-BAT refined analysis
  90. GRB050925: analysis of the XMM-Newton observation
  91. GRB051109A optical observations
  92. GRB 051114: Swift-BAT detection of a short burst
  93. GRB 051111: Further spectroscopic analysis
  94. GRB 051111: Radio afterglow
  95. GRB 051113: Swift-BAT refined analysis
  96. GRB 051113: Swift-BAT detection of a burst
  97. GRB 051111: AEOS optical observations
  98. GRB051103: Radio Observations
  99. GRB 051109A Milagro GeV/TeV Observations
  100. GRB/SGR 050925: XMM-Newton ToO observation

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