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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: Swift XRT refined analysis
  2. GRB 051221: Swift/UVOT upper limits
  3. GRB 051221: Possible nearby cluster
  4. GRB 051221: No variability in Gemini data
  5. GRB 051221: Correction to GCN #4368
  6. GRB 051221: Gemini observations
  7. GRB 051221: Improved astrometry of the IR counterpart
  8. GRB051221: K-band source
  9. GRB 051221: XRT position
  10. GRB 051221: Refined analysis of the Swift-BAT short hard burst
  11. GRB 051221: IR Observations at GRB+1hr
  12. GRB 051221: Swift detection of a bright short burst
  13. Refined analysis of the SWIFT J1626.6-5156
  14. Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156
  15. Refined analysis of the Swift-BAT detection of the RS CVn star II Peg
  16. GRB051211A (=H3979): Refined Analysis
  17. GRB 051211B: optical afterglow
  18. Swift detection of an RS CVn flare star
  19. GRB051211A: possible optical candidate
  20. Swift Trigger 172767 is not a GRB
  21. GRB 051215: near-infrared observations
  22. GRB051215 - SDSS pre-burst observations
  23. GRB 051215: Swift detection of a possible burst
  24. GRB 051215: A short GRB in a cluster?
  25. GRB051211B: Probable radio afterglow
  26. GRB051105: optical observations
  27. GRB 051213: Swift-BAT refined analysis
  28. GRB051211B: XRT refined analysis
  29. GRB 051211B, optical observation
  30. GRB 051213: Swift-BAT detection of a burst
  31. GRB 051211a: RTT150 optical observations
  32. GRB051211B, RBO optical observations
  33. GRB 051211A: Swift/UVOT upper limits
  34. GRB 051211B: Swift/UVOT upper limits - correction
  35. GRB 051211B: Swift/UVOT upper limits
  36. GRB 051211A,optical observation
  37. GRB 051211B: Swift XRT confirmation of the afterglow
  38. GRB051211B: Liverpool Telescope observation
  39. GRB 051211b: RTT150 optical observations
  40. GRB051211b: P60 Observations
  41. GRB 051211A and GRB051211B: BOOTES simultaneous observations
  42. GRB 051211B: Swift XRT Observations
  43. GRB 051210: Swift/UVOT upper limits
  44. GRB 051210: Magellan Imaging
  45. GRB 051211: TAROT optical limits
  46. GRB 051211B: a possible optical detection by TAROT
  47. GRB 051211B: a long GRB detected by INTEGRAL
  48. GRB 051211: Swift XRT upper limit
  49. GRB 051211:IAC80 optical observations
  50. HETE SXC localization of GRB 051211 (=H3979)
  51. GRB 051210: Optical imaging from Las Campanas
  52. GRB 051210: SALT detection limit
  53. GRB 051210: BAT further refined analysis of the short burst
  54. GRB 051210: Swift XRT refined analysis
  55. GRB 051210: FRAM early limit
  56. GRB 051210: Swift-BAT refined analysis of a short burst
  57. GRB051210: Swift UVOT Observation
  58. GRB 051210: A short GRB in a cluster?
  59. GRB 051210: Swift detection of a burst
  60. IPN observations of SGR1806-20
  61. Swift XRT positions
  62. An extraordinary long burst on December 3 from SGR1806-20
  63. IBAS Alert 2706 : not a real GRB
  64. Possible resuming of the SGR 1806-20 activity
  65. Swift UVOT Calibration Documentation
  66. GRB051117B: optical observation
  67. GRB051111: optical observaion
  68. Swift-BAT trigger 165579 is not a GRB
  69. GRB 051127: Swift-BAT detection of a possible burst
  70. GRB051117B: Swift XRT refined analysis
  71. GRB051117b: No Swift/UVOT Detection
  72. GRB051111: Rc optical observations: correction
  73. GRB 051117A: Swift/UVOT Detection of an Afterglow: Correction
  74. GRB 051117A: Swift/UVOT Detection of an Afterglow
  75. GRB051111: Suzaku WAM observation of the prompt emission
  76. GRB051111: Rc optical observations
  77. GRB051008: Suzaku WAM observation of the prompt emission
  78. GRB 051109B: GAO 150cm telescope Optical limit
  79. GRB 051109A : GAO 150cm telescope Rc-band detection
  80. GRB 051021 Optical Observations
  81. GRB 051117B: MARGE Optical Limits
  82. GRB 051117A and B: Radio Observations
  83. GRB 051117B: R and I observations of possible host galaxy
  84. GRB 051117b: NIR observations
  85. GRB 051117A: Refined analysis of the Swift-BAT burst
  86. GRB 051117B: Refined analysis of the Swift-BAT burst
  87. GRB051117A : XRT refined analysis
  88. GRB 051117B,optical observation
  89. GRB 051117B: Lulin R and I band observation
  90. GRB 051117B: Optical observations
  91. GRB 051117B: ROTSE-III Optical Limits
  92. GRB051117B: Swift XRT position
  93. GRB 051117B: Swift detection of a burst
  94. GRB 051117: Swift detection of a bright burst
  95. GRB051114: results of the Swift-XRT observation
  96. GRB 051028 Optical Observations
  97. GRB 051109B : Nainital upper limits
  98. GRB 051114: Radio Observations
  99. GRB 051114: Swift-BAT refined analysis
  100. GRB050925: analysis of the XMM-Newton observation

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