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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: Gemini observations
  2. GRB 051221: Improved astrometry of the IR counterpart
  3. GRB051221: K-band source
  4. GRB 051221: XRT position
  5. GRB 051221: Refined analysis of the Swift-BAT short hard burst
  6. GRB 051221: IR Observations at GRB+1hr
  7. GRB 051221: Swift detection of a bright short burst
  8. Refined analysis of the SWIFT J1626.6-5156
  9. Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156
  10. Refined analysis of the Swift-BAT detection of the RS CVn star II Peg
  11. GRB051211A (=H3979): Refined Analysis
  12. GRB 051211B: optical afterglow
  13. Swift detection of an RS CVn flare star
  14. GRB051211A: possible optical candidate
  15. Swift Trigger 172767 is not a GRB
  16. GRB 051215: near-infrared observations
  17. GRB051215 - SDSS pre-burst observations
  18. GRB 051215: Swift detection of a possible burst
  19. GRB 051215: A short GRB in a cluster?
  20. GRB051211B: Probable radio afterglow
  21. GRB051105: optical observations
  22. GRB 051213: Swift-BAT refined analysis
  23. GRB051211B: XRT refined analysis
  24. GRB 051211B, optical observation
  25. GRB 051213: Swift-BAT detection of a burst
  26. GRB 051211a: RTT150 optical observations
  27. GRB051211B, RBO optical observations
  28. GRB 051211A: Swift/UVOT upper limits
  29. GRB 051211B: Swift/UVOT upper limits - correction
  30. GRB 051211B: Swift/UVOT upper limits
  31. GRB 051211A,optical observation
  32. GRB 051211B: Swift XRT confirmation of the afterglow
  33. GRB051211B: Liverpool Telescope observation
  34. GRB 051211b: RTT150 optical observations
  35. GRB051211b: P60 Observations
  36. GRB 051211A and GRB051211B: BOOTES simultaneous observations
  37. GRB 051211B: Swift XRT Observations
  38. GRB 051210: Swift/UVOT upper limits
  39. GRB 051210: Magellan Imaging
  40. GRB 051211: TAROT optical limits
  41. GRB 051211B: a possible optical detection by TAROT
  42. GRB 051211B: a long GRB detected by INTEGRAL
  43. GRB 051211: Swift XRT upper limit
  44. GRB 051211:IAC80 optical observations
  45. HETE SXC localization of GRB 051211 (=H3979)
  46. GRB 051210: Optical imaging from Las Campanas
  47. GRB 051210: SALT detection limit
  48. GRB 051210: BAT further refined analysis of the short burst
  49. GRB 051210: Swift XRT refined analysis
  50. GRB 051210: FRAM early limit
  51. GRB 051210: Swift-BAT refined analysis of a short burst
  52. GRB051210: Swift UVOT Observation
  53. GRB 051210: A short GRB in a cluster?
  54. GRB 051210: Swift detection of a burst
  55. IPN observations of SGR1806-20
  56. Swift XRT positions
  57. An extraordinary long burst on December 3 from SGR1806-20
  58. IBAS Alert 2706 : not a real GRB
  59. Possible resuming of the SGR 1806-20 activity
  60. Swift UVOT Calibration Documentation
  61. GRB051117B: optical observation
  62. GRB051111: optical observaion
  63. Swift-BAT trigger 165579 is not a GRB
  64. GRB 051127: Swift-BAT detection of a possible burst
  65. GRB051117B: Swift XRT refined analysis
  66. GRB051117b: No Swift/UVOT Detection
  67. GRB051111: Rc optical observations: correction
  68. GRB 051117A: Swift/UVOT Detection of an Afterglow: Correction
  69. GRB 051117A: Swift/UVOT Detection of an Afterglow
  70. GRB051111: Suzaku WAM observation of the prompt emission
  71. GRB051111: Rc optical observations
  72. GRB051008: Suzaku WAM observation of the prompt emission
  73. GRB 051109B: GAO 150cm telescope Optical limit
  74. GRB 051109A : GAO 150cm telescope Rc-band detection
  75. GRB 051021 Optical Observations
  76. GRB 051117B: MARGE Optical Limits
  77. GRB 051117A and B: Radio Observations
  78. GRB 051117B: R and I observations of possible host galaxy
  79. GRB 051117b: NIR observations
  80. GRB 051117A: Refined analysis of the Swift-BAT burst
  81. GRB 051117B: Refined analysis of the Swift-BAT burst
  82. GRB051117A : XRT refined analysis
  83. GRB 051117B,optical observation
  84. GRB 051117B: Lulin R and I band observation
  85. GRB 051117B: Optical observations
  86. GRB 051117B: ROTSE-III Optical Limits
  87. GRB051117B: Swift XRT position
  88. GRB 051117B: Swift detection of a burst
  89. GRB 051117: Swift detection of a bright burst
  90. GRB051114: results of the Swift-XRT observation
  91. GRB 051028 Optical Observations
  92. GRB 051109B : Nainital upper limits
  93. GRB 051114: Radio Observations
  94. GRB 051114: Swift-BAT refined analysis
  95. GRB050925: analysis of the XMM-Newton observation
  96. GRB051109A optical observations
  97. GRB 051114: Swift-BAT detection of a short burst
  98. GRB 051111: Further spectroscopic analysis
  99. GRB 051111: Radio afterglow
  100. GRB 051113: Swift-BAT refined analysis

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