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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 100322B or possible Galactic transient detected in ground analysis of BAT data
  2. GRB 100316D: Spectroscopic Discovery of a Supernova from Magellan
  3. SGR 1833-0832: Swift/UVOT Upper Limits
  4. GRB 100322A: Fermi GBM detection
  5. SGR 1833-0832: Archival Chandra Observations
  6. SGR 1833-0832 is pulsed at 7.56 seconds
  7. SGR 1833-0832 is pulsed at 7.56 seconds
  8. Possible pulsation period in SGR 1833-0832
  9. Discovery of the Spin Period of SGR 1833-0832
  10. GRB 100316D: ATCA radio observations
  11. GRB 100319A: correction to GCN 10527
  12. Probable SGR 1833-0832: Swift-XRT refined analysis
  13. Probable SGR 1833-0832: Enhanced Swift-XRT position
  14. Swift-XRT refined position of the probable new SGR 1833-0832
  15. Swift-BAT refined analysis of the probable new SGR 1833-0832
  16. GRB 100219A: MASTER-Net optical alert observations
  17. GRB 100319A: Swift detection of a burst; possible SGR
  18. GRB 100316D: Possible Supernova
  19. GRB 100316D: Pre-burst emission measured by BAT
  20. GRB 100316D: Further Gemini observations
  21. GRB 100219A: optical upper limit
  22. GRB 100316A: optical observations in CrAO
  23. GRB 100316D: Swift/UVOT Observations
  24. GRB 100316D: Swift XRT enhanced position and further refined analysis
  25. GRB 100316B: Swift-XRT refined analysis
  26. Tentative redshift of GRB100316D from X-ray data
  27. GRB 100316C: GROND Detection of a Optical/NIR Afterglow Candidate
  28. Trigger 416226 is probably not a GRB
  29. GRB 100316D: GROND Detection of the Optical/NIR Afterglow Candidate
  30. GRB 100316D: Gemini/GMOS and VLT/X-shooter observations
  31. GRB 100316D: VLT/X-shooter observations
  32. GRB 100316D: Swift-BAT refined analysis
  33. GRB100316C: Swift/UVOT Upper Limits
  34. GRB 100316C: Swift-BAT refined analysis
  35. GRB 100316B: Swift/UVOT observations
  36. GRB 100316C: Swift-XRT team refined analysis
  37. GRB 100316C: Enhanced Swift-XRT position
  38. GRB 100316D: Swift XRT refined analysis
  39. GRB 100316A: TAROT Calern observatory optical observations
  40. GRB 100316A: Swift-XRT refined analysis
  41. GRB 100316B: Enhanced Swift-XRT position
  42. GRB 100316A: Swift-BAT refined analysis
  43. GRB 100316B: Swift-BAT refined analysis
  44. GRB100316A: Swift/UVOT Upper Limits
  45. Trigger 416140 is almost certainly not a GRB
  46. GRB 100316C: BOOTES-3 observations
  47. GRB 100316D: Swift detection of a burst
  48. GRB 100316B: VLT/X-shooter redshift
  49. GRB 100316B: Skynet/PROMPT Observations of Fading
  50. GRB 100316B: GROND Detection of the Optical/NIR Afterglow Candidate
  51. XRF 100315A: MAXI/GSC detection of a short X-ray transient
  52. GRB 100316C: Swift detection of a burst
  53. GRB 100316A: Enhanced Swift-XRT position
  54. GRB 100316B: Swift detection of a burst with optical counterpart
  55. GRB 100316 optical candidate from 1.23m CAHA telescope
  56. GRB 100316 optical candidate from 1.23m CAHA telescope
  57. GRB 100316A: Swift/UVOT Observations
  58. GRB 100316A: Swift-XRT detection
  59. GRB 100316A: Swift detection of a burst
  60. IBAS Alert 5992 is not a GRB, but XTE J1855-026
  61. GRB100305A: Optical upper limits at IAO
  62. GRB 100305A: Super-LOTIS early observations
  63. GRB100302A : LOAO observations and Lulin afterglow analysis
  64. GRB 100305A, Swift-BAT refined analysis
  65. GRB 100305A: Gemini z'-band observation
  66. GRB 100305A: Swift/UVOT Upper Limits
  67. GRB 100305A: Swift-XRT refined analysis
  68. GRB 100305A Optical Observations
  69. GRB 100305A: Enhanced Swift-XRT position
  70. GRB 100305A: Gemini-N OT candidate
  71. GRB 100305A: PAIRITEL NIR Upper Limits
  72. GRB 100305A: P60 Observations
  73. GRB 100305A: Swift detection of a burst
  74. GRB 100302A: Ondrejov 65cm limit
  75. GRB 100302A: Swift/UVOT Upper Limits
  76. GRB 100302A: Swift-XRT refined analysis
  77. GRB 100302A: Gemini-North redshift
  78. GRB 100302A: Gemini-N OT confirmation
  79. GRB 100302A: Optical observations at Crni Vrh
  80. GRB 100302A: MASTER-Net optical alert observations
  81. GRB 100302A, Swift-BAT refined analysis
  82. GRB 1000302A : A possible afterglow candidate
  83. GRB 100302A: Enhanced Swift-XRT position
  84. GRB 100302A: Skynet/DAO Observations
  85. GRB 100302A: Swift detection of a burst
  86. GRB 100224B: Fermi GBM detection
  87. GRB 100206A: optical observations in CrAO
  88. GRB 100206A: optical observations in Terskol
  89. GRB 100213B: Mondy optical observations
  90. GRB 100219A: optical observations
  91. GRB 100219A: GAO 150cm telescope Optical Observation
  92. GRB 100224A SHB found in ground analysis of BAT data
  93. GRB 100225A: Fermi LAT detection
  94. GRB 100225A: Fermi GBM detection
  95. GRB 100223A: Fermi GBM detection
  96. Swift Triggers 413744 and 413745 are not GRBs
  97. GRB
  98. GRB 100219A: X-shooter refined analysis
  99. GRB 100219A: XRT refined analysis
  100. GRB 100219A - Gemini South Spectroscopy

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