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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 090117B : Fermi GBM detection
  2. GRB 090117: confirmation of the X-ray afterglow
  3. GRB 090117C - Fermi GRB Detection
  4. GRB 090117 - Fermi GBM Observations
  5. GRB 090117: GROND Upper Limits
  6. GRB090117 Swift/UVOT upper limits
  7. GRB090117: Swift-XRT detection of a possible candidate afterglow
  8. GRB 090117 - SuperAGILE Localization of a long GRB
  9. GRB090102: MAGIC telescope GeV observation
  10. GRB 090112B: Suzaku WAM observation of the prompt emission
  11. GRB 090113: LOAO Detection Limits in R, I, z, Y-band
  12. GRB 090113: Swift UVOT upper limits
  13. GRB 090113: GROND Upper Limits
  14. GRB 090113: Swift-XRT refined analysis
  15. GRB 090113: Observations from NOT
  16. GRB 090113: Enhanced Swift-XRT position
  17. GRB 090113: Swift-BAT refined analysis
  18. GRB 090113: ROTSE-III Optical Limits
  19. GRB090113: XRT position
  20. GRB 090112B: Fermi GBM Detection
  21. GRB 090113: Swift detection of a burst
  22. GRB 090112: Fermi GBM detection
  23. GRB 090109: Fermi GBM detection
  24. GRB 090108B: Fermi GBM detection
  25. GRB 090111, Swift-BAT refined analysis
  26. GRB 090111: Swift UVOT Upper Limits
  27. GRB 090108: Fermi GBM Detection
  28. GRB 090111: Swift-XRT refined analysis
  29. GRB 090111: Enhanced Swift-XRT position
  30. GRB 090111: Swift detection of a burst
  31. GRB 090107B: Suzaku WAM observation of the prompt emission
  32. GRB090107B: Fermi GBM Detection
  33. GRB 090102: WSRT Radio Observations
  34. GRB 090107B: Swift XRT afterglow confirmation
  35. GRB 090107B: Swift/UVOT Observations
  36. GRB 090107B: Swift-XRT detection of possible afterglow
  37. GRB 090107B optical observations
  38. GRB 090107B: ROTSE-III Optical Limits
  39. GRB 090107B: a long GRB localized by INTEGRAL
  40. Fermi/GBM detection of GRB 081226A
  41. Fermi/GBM detection of GRB 081225
  42. GRB 090107: Swift-BAT refined analysis
  43. GRB 090107: Swift detection of a burst
  44. GRB 081231: Fermi GBM Detection
  45. GRB 090102: optical decay
  46. VLA radio upper limit on GRB 090102
  47. GRB 090102: GRT Optical Observation
  48. Swift triggered on the HMXB 1A 1118-61
  49. Konus-Wind observation of GRB 090102
  50. GRB 081229: Fermi GBM detection
  51. GRB 090102: Hobby-Eberly Telescope Spectroscopy
  52. GRB 090102: P60 Imaging and P200 Spectroscopy
  53. GRB 090102 Observations from IAC80
  54. GRB 090102: GROND observations of the optical afterglow
  55. Swift UVOT observations of GRB 090102
  56. GRB 090102: Swift-BAT refined analysis
  57. GRB 090102: Swift burst of interest
  58. GRB 090102: Swift XRT refined analysis
  59. GRB 090102: NOT redshift
  60. GRB 090102: Enhanced Swift-XRT position
  61. GRB 090102: TAROT Calern observatory optical light curve
  62. GRB 090102: REM observations of a bright afterglow
  63. GRB 090102: Swift detection of a burst with an optical counterpart
  64. GRB 090102: TAROT Calern observatory optical observations
  65. GRB 081230: GROND confirmation of the afterglow
  66. GRB 081230, Swift-BAT refined analysis
  67. GRB081230: Swift-XRT refined analysis
  68. GRB 081230 Swift/UVOT Observations
  69. GRB 081230: Enhanced Swift-XRT position
  70. GRB 081230: Swift/UVOT Detection of an Optical Afterglow
  71. GRB 081230: ROTSE-III Detection of Optical Counterpart
  72. GRB 081230: Swift detection of a burst
  73. GRB 081228: GROND confirmation of the optical/NIR afterglow
  74. GRB 081226B: Fermi GBM observation
  75. GRB 081226C: Fermi GBM detection
  76. GRB 081228, Swift-BAT refined analysis
  77. VLA radio detection of GRB 081221
  78. GRB 081228: Swift/UVOT Upper Limits
  79. GRB 081228: Swift-XRT Team refined analysis
  80. GRB 081228: detection by GROND
  81. GRB 081228: Enhanced Swift-XRT position
  82. GRB 081228: TAROT Calern observatory optical observations
  83. GRB 081228: Swift detection of a burst
  84. VLA radio observation of GRB 081221
  85. GRB 081226B: Swift XRT and UVOT upper limits
  86. GRB 081224: Suzaku WAM observation of the prompt emission
  87. GRB 081226: Swift-XRT refined analysis
  88. GRB 081226A: Swift UVOT Upper Limits
  89. GRB 081226: Second epoch of Gemini-South imaging
  90. GRB 081226A: Swift-BAT refined analysis
  91. GRB 081226B: a short-hard GRB detected by INTEGRAL
  92. GRB 081226: Gemini-South spectrum of possible afterglow
  93. GRB 081226: Gemini-South imaging
  94. GRB 081226: GROND afterglow candidate
  95. GRB 081226: ROTSE-III Optical Limits
  96. GRB 081226: Swift detection of a possible short-hard burst
  97. GRB 080810: optical observations
  98. GRB 081211B: optical observations
  99. GRB081224: LAT retraction
  100. GRB 081224: Swift-XRT observation

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