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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 090102: optical decay
  2. VLA radio upper limit on GRB 090102
  3. GRB 090102: GRT Optical Observation
  4. Swift triggered on the HMXB 1A 1118-61
  5. Konus-Wind observation of GRB 090102
  6. GRB 081229: Fermi GBM detection
  7. GRB 090102: Hobby-Eberly Telescope Spectroscopy
  8. GRB 090102: P60 Imaging and P200 Spectroscopy
  9. GRB 090102 Observations from IAC80
  10. GRB 090102: GROND observations of the optical afterglow
  11. Swift UVOT observations of GRB 090102
  12. GRB 090102: Swift-BAT refined analysis
  13. GRB 090102: Swift burst of interest
  14. GRB 090102: Swift XRT refined analysis
  15. GRB 090102: NOT redshift
  16. GRB 090102: Enhanced Swift-XRT position
  17. GRB 090102: TAROT Calern observatory optical light curve
  18. GRB 090102: REM observations of a bright afterglow
  19. GRB 090102: Swift detection of a burst with an optical counterpart
  20. GRB 090102: TAROT Calern observatory optical observations
  21. GRB 081230: GROND confirmation of the afterglow
  22. GRB 081230, Swift-BAT refined analysis
  23. GRB081230: Swift-XRT refined analysis
  24. GRB 081230 Swift/UVOT Observations
  25. GRB 081230: Enhanced Swift-XRT position
  26. GRB 081230: Swift/UVOT Detection of an Optical Afterglow
  27. GRB 081230: ROTSE-III Detection of Optical Counterpart
  28. GRB 081230: Swift detection of a burst
  29. GRB 081228: GROND confirmation of the optical/NIR afterglow
  30. GRB 081226B: Fermi GBM observation
  31. GRB 081226C: Fermi GBM detection
  32. GRB 081228, Swift-BAT refined analysis
  33. VLA radio detection of GRB 081221
  34. GRB 081228: Swift/UVOT Upper Limits
  35. GRB 081228: Swift-XRT Team refined analysis
  36. GRB 081228: detection by GROND
  37. GRB 081228: Enhanced Swift-XRT position
  38. GRB 081228: TAROT Calern observatory optical observations
  39. GRB 081228: Swift detection of a burst
  40. VLA radio observation of GRB 081221
  41. GRB 081226B: Swift XRT and UVOT upper limits
  42. GRB 081224: Suzaku WAM observation of the prompt emission
  43. GRB 081226: Swift-XRT refined analysis
  44. GRB 081226A: Swift UVOT Upper Limits
  45. GRB 081226: Second epoch of Gemini-South imaging
  46. GRB 081226A: Swift-BAT refined analysis
  47. GRB 081226B: a short-hard GRB detected by INTEGRAL
  48. GRB 081226: Gemini-South spectrum of possible afterglow
  49. GRB 081226: Gemini-South imaging
  50. GRB 081226: GROND afterglow candidate
  51. GRB 081226: ROTSE-III Optical Limits
  52. GRB 081226: Swift detection of a possible short-hard burst
  53. GRB 080810: optical observations
  54. GRB 081211B: optical observations
  55. GRB081224: LAT retraction
  56. GRB 081224: Swift-XRT observation
  57. GRB 081222: MITSuME optical observation
  58. GRB 081224: Fermi GBM Detection & LAT Localization
  59. GRB 080810: optical observations
  60. Konus-Wind observation of GRB 081222
  61. GRB 081223: Fermi GBM detection
  62. GRB 081221: GROND observations
  63. GRB 081222: Gemini-N confirmation of redshift z=2.77
  64. GRB 081222:Optical afterglow observation
  65. VLA radio upper limit on GRB 081222
  66. GRB 081222: Fermi GBM observation
  67. Fermi Gamma-ray Burst Monitor trigger 251687595 reclassification
  68. GRB 081222: Gemini-South absorption redshift
  69. GRB081222: Swift/UVOT further observations
  70. GRB 081221: Probable host galaxy in Keck imaging
  71. GRB 081204C: Fermi GBM detection
  72. GRB 081222, Swift-BAT refined analysis
  73. GRB 081221, Swift-BAT refined analysis
  74. GRB081222 optical limit by "Pi of the Sky"
  75. Konus-Wind observation of very bright GRB 081215A
  76. GRB 081222: Swift XRT refined analysis
  77. GRB081221: Fermi GBM observation
  78. Swift/UVOT observations of GRB 081221
  79. IPN triangulation of bright GRB 081215A
  80. GRB 081221: Swift-XRT Refined Analysis
  81. GRB 081221: pseudo-redshift (pz=0.7) from the spectral parameters of the prompt emission
  82. GRB 081222: Faulkes Telescope South observations
  83. GRB 081221: Gemini-N nIR imaging
  84. GRB081222, optical observation
  85. GRB081222: Swift/UVOT detection of an optical afterglow
  86. GRB081203A: BTA observation
  87. Konus-Wind observation of GRB 081221
  88. GRB 081222: GROND Detection of the Optical/NIR Afterglow
  89. GRB081222: REM candidate afterglow
  90. GRB 081222: Swift detection of a burst with a bright optical afterglow
  91. GRB 081221: Enhanced Swift-XRT position
  92. GRB 081221: further NOT observations
  93. GRB 081221: NOT observations
  94. GRB 081221: Swift detection of a burst
  95. GRB 081217: Fermi GBM detection
  96. Modification of Swift/UVOT response to bright GRBs
  97. GRB081215A: Fermi-LAT observations
  98. GRB 081211B: Further Swift-XRT analysis
  99. GRB 081215B: Fermi GBM detection
  100. GRB 081216: Suzaku WAM observation of the prompt emission

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