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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 100316A: Enhanced Swift-XRT position
  2. GRB 100316B: Swift detection of a burst with optical counterpart
  3. GRB 100316 optical candidate from 1.23m CAHA telescope
  4. GRB 100316 optical candidate from 1.23m CAHA telescope
  5. GRB 100316A: Swift/UVOT Observations
  6. GRB 100316A: Swift-XRT detection
  7. GRB 100316A: Swift detection of a burst
  8. IBAS Alert 5992 is not a GRB, but XTE J1855-026
  9. GRB100305A: Optical upper limits at IAO
  10. GRB 100305A: Super-LOTIS early observations
  11. GRB100302A : LOAO observations and Lulin afterglow analysis
  12. GRB 100305A, Swift-BAT refined analysis
  13. GRB 100305A: Gemini z'-band observation
  14. GRB 100305A: Swift/UVOT Upper Limits
  15. GRB 100305A: Swift-XRT refined analysis
  16. GRB 100305A Optical Observations
  17. GRB 100305A: Enhanced Swift-XRT position
  18. GRB 100305A: Gemini-N OT candidate
  19. GRB 100305A: PAIRITEL NIR Upper Limits
  20. GRB 100305A: P60 Observations
  21. GRB 100305A: Swift detection of a burst
  22. GRB 100302A: Ondrejov 65cm limit
  23. GRB 100302A: Swift/UVOT Upper Limits
  24. GRB 100302A: Swift-XRT refined analysis
  25. GRB 100302A: Gemini-North redshift
  26. GRB 100302A: Gemini-N OT confirmation
  27. GRB 100302A: Optical observations at Crni Vrh
  28. GRB 100302A: MASTER-Net optical alert observations
  29. GRB 100302A, Swift-BAT refined analysis
  30. GRB 1000302A : A possible afterglow candidate
  31. GRB 100302A: Enhanced Swift-XRT position
  32. GRB 100302A: Skynet/DAO Observations
  33. GRB 100302A: Swift detection of a burst
  34. GRB 100224B: Fermi GBM detection
  35. GRB 100206A: optical observations in CrAO
  36. GRB 100206A: optical observations in Terskol
  37. GRB 100213B: Mondy optical observations
  38. GRB 100219A: optical observations
  39. GRB 100219A: GAO 150cm telescope Optical Observation
  40. GRB 100224A SHB found in ground analysis of BAT data
  41. GRB 100225A: Fermi LAT detection
  42. GRB 100225A: Fermi GBM detection
  43. GRB 100223A: Fermi GBM detection
  44. Swift Triggers 413744 and 413745 are not GRBs
  45. GRB
  46. GRB 100219A: X-shooter refined analysis
  47. GRB 100219A: XRT refined analysis
  48. GRB 100219A - Gemini South Spectroscopy
  49. GRB 100216A: Swift/UVOT Observations
  50. GRB 100219A: VLT/X-shooter redshift
  51. GRB100219A Akeno and Okayama MITSuME Optical Observation
  52. GRB 100219A: GROND observations
  53. GRB 100219A: NOT OA observations
  54. GRB 100219A: Enhanced Swift-XRT position
  55. GRB 100219A: Swift/UVOT Detection of the Optical Afterglow
  56. GRB 100216A: XRT Refined Analysis
  57. GRB 100219A: Swift-BAT refined analysis
  58. GRB 100219A: Pre-explosion imaging and host candidate
  59. GRB 100219A: Swift/UVOT Detection of a Source near the XRT Position
  60. GRB 100218A : Fermi GBM detection
  61. GRB 100219A: Swift detection of a burst
  62. GRB 100216A: Keck imaging
  63. GRB 100216A Short, hard GRB detected in ground analysis of Swift-BAT data
  64. GRB 100213A: Swift-BAT lag analysis indicates probably SHB
  65. GRB 100213B: GRT Optical Observation
  66. GRB 100213A: GRT Optical Observation
  67. GRB 100213A: Swift-BAT refined analysis
  68. GRB 100213B: Enhanced Swift-XRT position
  69. GRB 100213B: Gemini-N Observations
  70. GRB 100213B: Swift/UVOT Upper Limits
  71. GRB 100213A: Swift/UVOT Upper Limits
  72. GRB 100213B: PAIRITEL NIR Upper Limits
  73. GRB 100213A: Enhanced Swift-XRT position
  74. GRB 100213B: Swift-BAT refined analysis
  75. GRB 100213B: Swift XRT refined analysis
  76. GRB 100213A: SARA observations
  77. GRB 100213A: Swift XRT refined analysis
  78. GRB 100213B: NOT optical observations
  79. GRB 100213B: Swift detection of a burst
  80. GRB 100213A: Swift detection of a burst
  81. GRB 100206A: Second epoch Gemini-north observations and afterglow limits
  82. Swift/UVOT observations of GRB100212A - correction of the name of the burst
  83. Swift/UVOT observations of GRB120212A
  84. GRB 100212A: LOAO R-band Detection/V-band Observation
  85. GRB 100212A: Fermi GBM detection
  86. GRB 100212A: Swift XRT refined analysis
  87. GRB 100212A: Swift-BAT refined analysis
  88. GRB 100212A: Enhanced Swift-XRT position
  89. GRB 100212A: candidate optical afterglow
  90. GRB 100212A: Swift detection of a burst
  91. GRB 091127: Detection of a Supernova
  92. GRB 100205A: Keck limits on an underlying host galaxy
  93. GRB 100205A: BOAO/LOAO zYJK observation
  94. GRB 100205B: Fermi GBM detection
  95. GRB 100206A: GROND upper limits
  96. GRB 100206A: Gemini-North observations
  97. GRB 100206A: Swift/UVOT Upper Limits
  98. GRB 100131A: MASTER-Net optical alert observations
  99. GRB 100206A: YNAO-GMG observations
  100. GRB 100206A: MASTER-Net optical alert observations

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