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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"

2744 results found.

  1. GRB 091020: Late TLS detection
  2. GRB 090926A: Late-time Gemini South Observations and Possible Jet Break
  3. Fwd: GRB 091003: Possible Supernova Component Retraction
  4. GRB 091003: Possible Supernova Component
  5. GRB 091003: Gemini-N redshift of possible host galaxy
  6. GRB 091010: optical afterglow candidate rejection
  7. GRB 091010: Swift-XRT position
  8. GRB 091003: Lick observations and possible SDSS host galaxy
  9. GRB 090831B: Swift detection of a possible burst
  10. GRB 090823: Swift XRT possible detection of the X-ray afterglow
  11. GRB 090817: Swift/UVOT Observations of a Possible Late-Time Brightening
  12. GRB 090817: aphotometry of USNO-B1.0 341-0096763
  13. GRB 090814B: Swift-XRT detection of a possible afterglow.
  14. GRB 090814A: Swift-BAT refined analysis
  15. GRB 090809: Swift detection of a burst with a possible optical counterpart
  16. GRB 090807: Swift-XRT refined analysis
  17. GRB 090807, Swift-BAT refined analysis
  18. GRB 090727: Liverpool Telescope possible OT candidate
  19. GRB 090726: Swift-XRT position of probable counterpart
  20. GRB 090720: Gemini-North Imaging and Optical Afterglow
  21. GRB 090715B: Swift detection of a burst with a possible optical counterpart
  22. GRB 090621B: MTM-500 optical observations
  23. Possible GRB090705: Swift-XRT observations
  24. GRB 090705: PAIRITEL NIR Observations
  25. GRB 090705: Swift detection of a possible burst
  26. GRB 090404: Deep optical imaging and possible host association (correction)
  27. GRB 090404: Deep optical imaging and possible host association
  28. GRB 090628: Swift detection of a burst
  29. GRB 090621A: Swift-BAT refined analysis
  30. Ignore GCN/Swift-BAT Lightcurve Notices for trigger 353567
  31. GRB 090531: Swift-BAT refined analysis
  32. GRB 090529: Swift-BAT refined analysis
  33. GRB 090516B: Fermi GBM detection
  34. GRB090510: VLT/FORS2 spectroscopic redshift
  35. GRB 090510: Swift/UVOT host galaxy candidates
  36. GRB 090418A: optical observation
  37. GRB 090424: optical observations
  38. GRB090429B: Gemini-N infrared IR candidate
  39. GRB 090423: pseudo burst at z=1 and its relation to GRB 080913
  40. GRB 090423: Swift/BAT spectral lag results
  41. GRB 090422: Liverpool Telescope possible candidate
  42. VLA observations of short burst GRB 090417A
  43. GRB 090417B: optical observations
  44. GRB 090412: Fermi GBM detection
  45. Swift-BAT trigger 348781: almost certainly not a burst
  46. Fermi GBM Detection of a weak source
  47. GRB 090404: Swift detection of a burst
  48. GRB 090401B: Swift detection of a burst
  49. GRB 090328B: MASTER-Irkutsk prompt optical short burst observations
  50. GRB 090401: Swift detection of a burst
  51. GRB090323: Optical observations from NOT
  52. GRB 090328: Possible Swift/XRT detection
  53. GRB 090323: TLS detection at 5 days, no break
  54. GRB 090320B: MASTER-Net prompt optical observations
  55. GRB 090323 TLS detection - still bright
  56. GRB 090323: Possible XRT Counterpart
  57. GRB 090313: VLT spectroscopy
  58. GRB090305B: MASTER-net prompt optical short burst observations
  59. GRB 090306B: Possible XRT afterglow
  60. GRB 090306: Swift detection of a possible burst
  61. GRB 090303: Fermi GBM detection
  62. GRB 081211B: Nearby cluster
  63. GRB 090201: Swift-XRT detection of the possible X-ray afterglow
  64. AXP 1E1547.0-5408: Fermi GBM observations
  65. Trigger 340734: Swift detection of a possible short burst
  66. GRB 090118 (BATSS): GRT Optical Observation
  67. GRB 090118: GROND Upper Limits
  68. GRB 090118: Possible burst detection from Swift-BAT slew data
  69. GRB090117: Swift-XRT detection of a possible candidate afterglow
  70. GRB090113: XRT position
  71. GRB 090112: Fermi GBM detection
  72. GRB 090107B: Swift-XRT detection of possible afterglow
  73. GRB 090107: Swift detection of a burst
  74. GRB 081228, Swift-BAT refined analysis
  75. GRB 081228: Swift-XRT Team refined analysis
  76. GRB 081226: Swift-XRT refined analysis
  77. GRB 081226A: Swift UVOT Upper Limits
  78. GRB 081226: Gemini-South spectrum of possible afterglow
  79. GRB 081226: Swift detection of a possible short-hard burst
  80. GRB 081211B: Further Swift-XRT analysis
  81. Possible GRB 081211B: Swift/UVOT Upper Limits
  82. Possible GRB 081211B - Swift-XRT analysis
  83. GRB 081211B(?): Possible burst detection from Swift-BAT slew data
  84. GRB 081211: Swift-BAT refined analysis
  85. GRB 081210: Swift-BAT refined analysis
  86. GRB 081128: optical observation in CrAO
  87. GRB 081204: Swift XRT afterglow candidate
  88. GRB 081203B: Swift-XRT candidate afterglow.
  89. GRB 081130B: MASTER prompt optical observations
  90. GRB 081128: optical observation
  91. GRB 081130B: Fermi GBM detection
  92. GRB 081128A: optical observations
  93. Trigger 335971: Swift possible detection of a burst
  94. GRB081128 : Lulin optical follow-ups
  95. GRB 081128: Swift detection of a burst
  96. GRB 081126: Confirmation of the Optical Afterglow
  97. Fermi GBM detection of a weak source
  98. GRB 081118: optical afterglow candidate
  99. GRB 081109A: confirmation of possible detection host galaxy
  100. GRB 081024B: Swift-XRT late-time observations

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