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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. IceCube-210922A: No neutrino counterpart candidates in ANTARES search
  2. GRB 210923B: GECAM detection
  3. Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB
  4. IceCube-210922A: Upper limits from a search for additional neutrino events in IceCube
  5. IceCube-210922A: Upper limits from Fermi-GBM Observations
  6. IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility
  7. GECAM observations of a series of bursts from SGR J1935+2154 (2021-09-15T14 to 2021-09-23T14)
  8. GRB 210919A: DECam Upper Limits
  9. Fermi-LAT Gamma-ray Observations of IceCube-210922A
  10. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 September 22
  11. GRB 210923A: Fermi GBM Final Real-time Localization
  12. IceCube Alert 210922.76: Global MASTER-Net observations report
  13. GRB 210919A: Swift-BAT refined analysis
  14. IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event
  15. GRB 210912A: LBT optical observations
  16. GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
  17. GRB 210919a: Lowell Discovery Telescope upper limits
  18. GRB210919A: Keck NIRC2 Kp band upper limits
  19. GRB 210919A: Swift/UVOT Upper Limits
  20. GRB 210919A: LOAO and LSGT optical upper limits
  21. GRB 210919A: MITSuME Akeno optical upper limits
  22. GRB 210919A: Swift-XRT refined Analysis
  23. GRB 210919B: Fermi GBM Final Real-time Localization
  24. GRB 210919A: NOT upper limits
  25. GRB 210919A: AbAO optical upper limit
  26. GRB 210919A: Enhanced Swift-XRT position
  27. GRB 210919A: LCO Optical Upper Limit
  28. GRB 210919A: BOOTES-2/TELMA optical upper limit
  29. Swift GRB 210919A: Global MASTER-Net observations report
  30. GRB 210919A: Swift detection of a short burst
  31. Swift trigger 1073821: detection of IGR J16418-4532
  32. GRB 210912A: BOOTES-5/JGT optical afterglow candidate (Correction to GCNC 30823)
  33. GRB 210917A: Fermi GBM Final Real-time Localization
  34. GRB 210812A is not a compelling example of a lensed GRB
  35. GECAM observations of bursts from SGR J1935+2154 (2021-09-13T01 to 2021-09-15T14)
  36. GRB 210909A: Detection by GRBAlpha
  37. GRB 210912A: Swift-BAT refined analysis
  38. Konus-Wind observation of the recent SGR 1935+2154 activity
  39. GRB 210912A: Tautenburg observations
  40. GECAM observations of bursts from SGR J1935+2154 (2021-09-12T05 to 2021-09-13T01)
  41. AGILE observations of two bright bursts from SGR 1935+2154
  42. GRB 210912A: CAHA 2.2m Detection
  43. GRB 210912A: Swift-XRT refined Analysis
  44. GRB 210912A: Swift/UVOT Detection
  45. Fermi GBM observation of another bright burst in the direction of SGR 1935+2154
  46. GRB 210912A: Enhanced Swift-XRT position
  47. GRB 210912A: Host-galaxy candidate in PanSTARRS
  48. Fermi trigger No 653151835: Global MASTER-Net observations report
  49. Fermi trigger No 653124492: Global MASTER-Net observations report
  50. Fermi trigger No 653122278: Global MASTER-Net observations report
  51. GRB 210912A: Mondy optical afterglow confirmation
  52. Swift GRB 210912A: Global MASTER-Net observations report
  53. GRB 210912A: BOOTES-5/JGT optical afterglow candidate
  54. GECAM observations of bursts from SGR J1935+2154 (2021-09-11T07 to 2021-09-12T08)
  55. GRB 210912B: Fermi GBM Final Real-time Localization
  56. GRB 210912A: Swift detection of a burst
  57. Fermi trigger No 653093506: Global MASTER-Net observations report
  58. Fermi trigger No 653066776: Global MASTER-Net observations report
  59. Fermi trigger No 653084584: Global MASTER-Net observations report
  60. Fermi trigger No 653083551: Global MASTER-Net observations report
  61. Fermi trigger No 653079281: Global MASTER-Net observations report
  62. Fermi trigger No 653066130: Global MASTER-Net observations report
  63. Fermi trigger No 653072474: Global MASTER-Net observations report
  64. Fermi trigger No 653071808: Global MASTER-Net observations report
  65. Fermi trigger No 653054042: Global MASTER-Net observations report
  66. Fermi trigger No 653049776: Global MASTER-Net observations report
  67. Fermi trigger No 653022153: Global MASTER-Net observations report
  68. Fermi trigger No 653031163: Global MASTER-Net observations report
  69. Swift GRB210910.42: Global MASTER-Net observations report
  70. Fermi GBM observation of a bright flare in the direction of SGR 1935+2154
  71. Fermi trigger No 653010039: Global MASTER-Net observations report
  72. Konus-Wind detection of the second intermediate flare from SGR 1935+2154
  73. IPN triangulation of a bright burst from SGR 1935+2154
  74. Fermi trigger No 652957973: Global MASTER-Net observations report
  75. Fermi trigger No 652944960: Global MASTER-Net observations report
  76. Fermi trigger No 652981861: Global MASTER-Net observations report
  77. GRB 210826A: further Swift-XRT observations
  78. GRB 210909B: GECAM detection
  79. GECAM observations of a series of bursts from SGR J1935+2154
  80. Swift detection of a burst from SGR Swift J1555.2-5402
  81. Fermi trigger No 652934203: Global MASTER-Net observations report
  82. GECAM observation of a burst from SGR J1935+2154
  83. GECAM observation of a burst from SGR J1935+2154
  84. Fermi trigger No 652927551: Global MASTER-Net observations report
  85. GRB 210619B: Maidanak and Assy optical observations, broken power law parametrization
  86. Fermi trigger No 652911693: Global MASTER-Net observations report
  87. Fermi trigger No 652906639: Global MASTER-Net observations report
  88. Fermi GRB 210909A: Global MASTER-Net observations report
  89. GECAM observation of a burst from SGR J1555.2-5402
  90. GRB 210909A: Fermi GBM Final Real-time Localization
  91. GRB 210905A: Swift/UVOT Upper Limits
  92. GRB 210905A: ATCA detection
  93. GRB 210905A: ALMA detection
  94. GRB 210905A: AstroSat CZTI detection
  95. GRB 210905A, GROND observations
  96. Konus-Wind detection of GRB 210905A
  97. Fermi GBM Sub-Threshold Detection of GRB 210905A
  98. Fermi GBM trigger 652585475 / 210906073 is not a GRB
  99. Fermi trigger No 652585475: Global MASTER-Net observations report
  100. GRB 210905A: Swift-XRT refined Analysis

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