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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 100619A: Swift-BAT refined analysis
  2. GRB 100619A: Swift detection of a burst
  3. GRB 100614A: Gemini/NIRI Observations
  4. GRB 100615A: Gemini/NIRI Observations
  5. XRF 100616a : MAXI/GSC detection of a probable XRF
  6. Fermi GBM trigger 100612038 is not a GRB
  7. GRB 100615A: Swift/UVOT Upper Limits
  8. GRB 100614A: Swift/UVOT Upper Limits
  9. GRB 100614A: NOT optical upper limits
  10. GRB 100614A: MASTER-Net optical alert observations
  11. GRB 100614A: Swift-BAT refined analysis
  12. GRB 100615A: Fermi GBM detection
  13. GRB 100615A: Swift-BAT refined analysis
  14. GRB 100614A: Enhanced Swift-XRT position
  15. GRB 100615A: Enhanced Swift-XRT position
  16. GRB 100615A: Swift-XRT refined analysis
  17. GRB 100614A: Swift-XRT refined analysis
  18. GRB 100614 : XMM-Newton observation
  19. GRB 100615A: GROND observations, upper limits
  20. GRB 100615A: PAIRITEL NIR Upper Limits
  21. GRB 100615A: NTT/Ultracam imaging
  22. GRB 100615A: Swift detection of a burst
  23. GRB 100614A: WHT I-band observations
  24. GRB 100614A: BOOTES-2/TELMA optical observations
  25. GRB 100614A: Liverpool Telescope Observations
  26. GRB 100614A: Swift detection of a burst
  27. GRB 100606A: Suzaku WAM observation of the prompt emission
  28. GRB 100606A: GROND observations
  29. Trigger 424161: Swift/BAT trigger on XTE J1946+274/GRO J1944+26
  30. Konus-Wind observation of GRB 100606A
  31. Radio detection of GRB100418a with ATCA
  32. GRB 100606A: Gemini-South imaging
  33. GRB 100606A: Swift/UVOT Upper Limits
  34. GRB 100606A Swift-XRT refined analysis
  35. GRB 100606A: Swift-BAT refined analysis
  36. GRB 100606A: Enhanced Swift-XRT position
  37. Swift Trigger 424040 is not a GRB
  38. GRB 100606A: Prompt enhanced Swift-XRT position
  39. GRB 100606A: Swift detection of a burst
  40. Swift detection of outburst from the SFXT IGR J18410-0535
  41. GRB 100111A: Maidanak optical observations
  42. GRB 100418A: Maidanak optical observations
  43. GRB 100513A: CrAO optical observations
  44. GRB 100514A: CrAO optical observations
  45. GRB 100526A: optical upper limit
  46. Konus-Wind observation of GRB 100528A
  47. GRB 100528A: Faulkes Telescope North Detection
  48. GRB 100528A: GROND detection in all bands
  49. GRB 100528A: NOT optical observation
  50. Swift UVOT and UVOT-enhanced XRT position for GRB 100528A
  51. GRB100526B: GROND Upper limits
  52. GRB 100528A: Fermi GBM observation
  53. GRB 100528A: SuperAGILE Localization of a Long GRB
  54. GRB 100526B: Swift-XRT confirmation of fading afterglow
  55. GRB 100526B: Swift/UVOT Upper Limits
  56. GRB 100526A: Swift/UVOT Upper Limits
  57. GRB 100526A: Gemini/NIRI infrared afterglow candidate
  58. GRB 100526A: NOT optical upper limit
  59. GRB 100526A: Swift XRT refined analysis
  60. GRB 100526B: Swift-BAT refined analysis
  61. GRB 100526B: Swift XRT/UVOT observations
  62. GRB 100526A: Swift-BAT refined analysis
  63. GRB 100526A: Enhanced Swift-XRT position
  64. GRB 100526B: Swift detection of a probable GRB
  65. GRB 100526A: MASTER-Net optical alert observations
  66. GRB 100526A: Swift detection of a burst
  67. Konus-Wind observation of GRB 100522A
  68. GRB100522A: Suzaku WAM observation of the prompt emission
  69. GRB 100418A: Subaru late-time optical imaging and spectroscopy
  70. GRB 100522A: GROND observations, upper limits
  71. Swift/UVOT observations of GRB100522A.
  72. GRB 100522A: Fermi GBM observation
  73. GRB 100522A: Swift XRT refined analysis
  74. GRB 100522A, Swift-BAT refined analysis
  75. GRB 100522A: Enhanced Swift-XRT position
  76. GRB 100522A: NIR observations from CAHA
  77. GRB 100522A: BOOTES-2 optical limit
  78. GRB 100522A: Swift detection of a burst
  79. GRB 100418A: CrAO optical observations
  80. GRB 100518A: GROND afterglow observation and photo-z
  81. GRB 100518A: Swift/UVOT Upper Limits
  82. GRB 100518A: Swift-XRT refined analysis
  83. GRB 100518A: optical afterglow decay
  84. GRB 100518A: BOOTES-3 optical observations
  85. Update to the configuration of the Fermi-LAT onboard GRB search
  86. GRB 100518A: Faulkes Telescope North Afterglow Candidate
  87. GRB 100518A: Swift target of opportunity observation of the INTEGRAL burst
  88. GRB 100513A: MITSuME Akeno Optical Observation
  89. Swift-BAT trigger 422437 is not anything astrophysical
  90. GRB 100518A: a long GRB detected with INTEGRAL
  91. Swift Trigger 422437 is probably not a GRB
  92. Fermi/GBM trigger 295791986 - unreliable location
  93. GRB 100517A: MASTER-Net wide field camera prompt optical observations
  94. GRB 100513A: EVLA radio observation
  95. GRB 100514A: optical afterglow confirmation
  96. GRB 100514A: Swift/UVOT Observations
  97. GRB 100514A: YNAO-GMG observations
  98. GRB 100514A: Swift XRT refined analysis
  99. GRB 100514A: MASTER-Net optical observations
  100. GRB 100514A: Enhanced Swift-XRT position

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