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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"

12335 results found.

  1. GRB 100205A: GROND upper limits
  2. GRB 100206A: Swift detection of a short hard burst
  3. GRB 100205A: Swift UVOT upper limits
  4. GRB 100203A: Swift XRT and UVOT refined analyses
  5. GRB 100205A: Swift detection of a burst
  6. Short X-ray Transient detected by MAXI/GSC
  7. Swift/UVOT refined analysis of GRB100117A
  8. GRB 100117A: Swift-XRT refined analysis
  9. GRB 100117A: Gemini-North upper limit
  10. GRB 100117A: Swift detection of a short hard burst
  11. GRB 100115A: Swift/UVOT Upper Limits
  12. GRB 100111A: PAIRITEL NIR Upper Limits
  13. GRB 100111A: Swift UVOT Refined Analysis
  14. GRB 100103A: GROND Upper Limits
  15. GRB 100103A: Swift/UVOT Upper Limits
  16. Swift Trigger 381591 is probably not a burst
  17. GRB 091231: GROND NIR observations
  18. Swift Trigger 381591: Uncatalogued UVOT Source
  19. GRB 091230: Swift/UVOT Observations
  20. Trigger 381591: Swift detection of a possible burst
  21. Swift Trigger 381434 is not a GRB
  22. Trigger 381434: Swift detection of a possible burst
  23. GRB 091221 : IRSF NIR upper limit
  24. GRB 091221: Swift/UVOT refined analysis
  25. GRB 091221: UVOT Confirmation of an Optical Afterglow
  26. GRB 091221: Swift detection of a burst
  27. Swift trigger 379449 (possible GRB) is not a burst
  28. GRB 091215: Faulkes Telescope North observations
  29. Trigger 379449: Swift detection of a possible burst
  30. GRB091208A: Swift/UVOT refined analysis
  31. GRB 091208A: Swift-XRT observations
  32. GRB 091208A, RIMOTS optical upper limits
  33. GRB 091208B, RIMOTS optical upper limits
  34. Short X-ray Transient, RIMOTS optical upper limits
  35. GRB 091202: Swift/UVOT Upper Limits
  36. Short X-ray Transient Detection by MAXI/GSC
  37. GRB 091130A: Xinglong TNT upper limit
  38. GRB 091130B: Swift/UVOT Upper Limits
  39. Swift trigger 377436 (possible GRB 091130A) is not a burst
  40. GRB 091130B: Swift detection of a burst
  41. GRB 091127: Radio observations
  42. GRB 091117A: Swift/UVOT followup observations
  43. GRB 091117: Swift-XRT observations
  44. GRB 091109A: GROND and VLT observations
  45. GRB 091109B: Swift/UVOT Upper Limits
  46. GRB 091109B: Swift detection of a short burst
  47. GRB 091109: Swift/UVOT observations
  48. GRB 091104: Swift/UVOT Upper Limits
  49. GRB091026 : IRSF NIR upper limit
  50. GRB091102 : MOA optical upper limit
  51. GRB 091104: Swift detection of a burst
  52. Fermi LAT Upper Limits on GRB 091010
  53. GRB 091102 : Faulkes Telescope South Upper Limits
  54. GRB 091102: Swift/UVOT Upper Limits
  55. GRB 091102: GROND Upper Limits
  56. GRB 091102: Swift/UVOT Finding Chart Observation
  57. GRB 091024: Fermi LAT upper limits
  58. GRB091029: Swift/UVOT observations
  59. GRB 091024: Keck/LRIS Spectroscopy
  60. GRB 091026: GROND Upper Limits
  61. GRB 091026: Swift/UVOT Upper Limits
  62. GRB 091026: Swift detection of a Gamma Ray Burst
  63. GRB 091020 : Xinglong TNT upper limit
  64. GRB091024 Swift/UVOT Upper Limits
  65. GRB 091024: TLS Upper Limit
  66. GRB 091024: GRAS004 optical observations
  67. GRB091020 Swift/UVOT observations
  68. GRB 091020: NOT spectroscopic redshift
  69. Konus-RF observation of GRB 091018
  70. GRB 090726 R band observations
  71. GRB 091010: optical afterglow candidate rejection
  72. GRB 091010: AGILE-MCAL measurement and GRID upper limit
  73. GRB 091010 optical upper limits
  74. GRB 091010: Swift/UVOT Upper Limits
  75. GRB 091003: WHT ACAM observations
  76. Konus-Wind observation of GRB 091003A
  77. GRB 091003: Swift/UVOT Detection of an Optical Afterglow
  78. GRB 090929A: Swift/UVOT Observations
  79. GRB 090929A: Swift-XRT non-detection
  80. GRB 090929B: Gemini-N upper limits
  81. GRB 090929B: Swift/UVOT Observations
  82. Konus-RF observation of GRB 090929A
  83. GRB 090929B: Swift detection of a burst
  84. GRB090926B: Swift/UVOT Upper Limits
  85. GRB 090926B: Swift detection of a burst
  86. GRB090904B : IRSF NIR upper limit
  87. GRB 090916: Swift-XRT upper limit
  88. GRB 090915: GROND upper limits
  89. GRB 090915: Swift-XRT detection of a fading X-ray counterpart
  90. GRB 090827: Confirmation of the X-ray afterglow
  91. GRB 090912: Swift/UVOT Upper Limits
  92. GRB 090912 optical upper limit
  93. GRB 090823: Swift XRT confirmation of the X-ray afterglow
  94. GRB 090904A: Swift/UVOT Refined Analysis
  95. GRB 090904B: Swift/UVOT Refined Analysis
  96. GRB 090904B: Swift detection of a burst
  97. GRB 090831C: GROND upper limits
  98. Swift Trigger 361477, called GRB090831B, is probably not real.
  99. GRB090831C: Swift/UVOT upper limits
  100. GRB 090831B: MITSuME optical upper limits

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