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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').
  1. GRB 210919A: DECam Upper Limits
  2. Fermi-LAT Gamma-ray Observations of IceCube-210922A
  3. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 September 22
  4. GRB 210923A: Fermi GBM Final Real-time Localization
  5. IceCube Alert 210922.76: Global MASTER-Net observations report
  6. GRB 210919A: Swift-BAT refined analysis
  7. IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event
  8. GRB 210912A: LBT optical observations
  9. GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
  10. GRB 210919a: Lowell Discovery Telescope upper limits
  11. GRB210919A: Keck NIRC2 Kp band upper limits
  12. GRB 210919A: Swift/UVOT Upper Limits
  13. GRB 210919A: LOAO and LSGT optical upper limits
  14. GRB 210919A: MITSuME Akeno optical upper limits
  15. GRB 210919A: Swift-XRT refined Analysis
  16. GRB 210919B: Fermi GBM Final Real-time Localization
  17. GRB 210919A: NOT upper limits
  18. GRB 210919A: AbAO optical upper limit
  19. GRB 210919A: Enhanced Swift-XRT position
  20. GRB 210919A: LCO Optical Upper Limit
  21. GRB 210919A: BOOTES-2/TELMA optical upper limit
  22. Swift GRB 210919A: Global MASTER-Net observations report
  23. GRB 210919A: Swift detection of a short burst
  24. Swift trigger 1073821: detection of IGR J16418-4532
  25. GRB 210912A: BOOTES-5/JGT optical afterglow candidate (Correction to GCNC 30823)
  26. GRB 210917A: Fermi GBM Final Real-time Localization
  27. GRB 210812A is not a compelling example of a lensed GRB
  28. GECAM observations of bursts from SGR J1935+2154 (2021-09-13T01 to 2021-09-15T14)
  29. GRB 210909A: Detection by GRBAlpha
  30. GRB 210912A: Swift-BAT refined analysis
  31. Konus-Wind observation of the recent SGR 1935+2154 activity
  32. GRB 210912A: Tautenburg observations
  33. GECAM observations of bursts from SGR J1935+2154 (2021-09-12T05 to 2021-09-13T01)
  34. AGILE observations of two bright bursts from SGR 1935+2154
  35. GRB 210912A: CAHA 2.2m Detection
  36. GRB 210912A: Swift-XRT refined Analysis
  37. GRB 210912A: Swift/UVOT Detection
  38. Fermi GBM observation of another bright burst in the direction of SGR 1935+2154
  39. GRB 210912A: Enhanced Swift-XRT position
  40. GRB 210912A: Host-galaxy candidate in PanSTARRS
  41. Fermi trigger No 653151835: Global MASTER-Net observations report
  42. Fermi trigger No 653124492: Global MASTER-Net observations report
  43. Fermi trigger No 653122278: Global MASTER-Net observations report
  44. GRB 210912A: Mondy optical afterglow confirmation
  45. Swift GRB 210912A: Global MASTER-Net observations report
  46. GRB 210912A: BOOTES-5/JGT optical afterglow candidate
  47. GECAM observations of bursts from SGR J1935+2154 (2021-09-11T07 to 2021-09-12T08)
  48. GRB 210912B: Fermi GBM Final Real-time Localization
  49. GRB 210912A: Swift detection of a burst
  50. Fermi trigger No 653093506: Global MASTER-Net observations report
  51. Fermi trigger No 653066776: Global MASTER-Net observations report
  52. Fermi trigger No 653084584: Global MASTER-Net observations report
  53. Fermi trigger No 653083551: Global MASTER-Net observations report
  54. Fermi trigger No 653079281: Global MASTER-Net observations report
  55. Fermi trigger No 653066130: Global MASTER-Net observations report
  56. Fermi trigger No 653072474: Global MASTER-Net observations report
  57. Fermi trigger No 653071808: Global MASTER-Net observations report
  58. Fermi trigger No 653054042: Global MASTER-Net observations report
  59. Fermi trigger No 653049776: Global MASTER-Net observations report
  60. Fermi trigger No 653022153: Global MASTER-Net observations report
  61. Fermi trigger No 653031163: Global MASTER-Net observations report
  62. Swift GRB210910.42: Global MASTER-Net observations report
  63. Fermi GBM observation of a bright flare in the direction of SGR 1935+2154
  64. Fermi trigger No 653010039: Global MASTER-Net observations report
  65. Konus-Wind detection of the second intermediate flare from SGR 1935+2154
  66. IPN triangulation of a bright burst from SGR 1935+2154
  67. Fermi trigger No 652957973: Global MASTER-Net observations report
  68. Fermi trigger No 652944960: Global MASTER-Net observations report
  69. Fermi trigger No 652981861: Global MASTER-Net observations report
  70. GRB 210826A: further Swift-XRT observations
  71. GRB 210909B: GECAM detection
  72. GECAM observations of a series of bursts from SGR J1935+2154
  73. Swift detection of a burst from SGR Swift J1555.2-5402
  74. Fermi trigger No 652934203: Global MASTER-Net observations report
  75. GECAM observation of a burst from SGR J1935+2154
  76. GECAM observation of a burst from SGR J1935+2154
  77. Fermi trigger No 652927551: Global MASTER-Net observations report
  78. GRB 210619B: Maidanak and Assy optical observations, broken power law parametrization
  79. Fermi trigger No 652911693: Global MASTER-Net observations report
  80. Fermi trigger No 652906639: Global MASTER-Net observations report
  81. Fermi GRB 210909A: Global MASTER-Net observations report
  82. GECAM observation of a burst from SGR J1555.2-5402
  83. GRB 210909A: Fermi GBM Final Real-time Localization
  84. GRB 210905A: Swift/UVOT Upper Limits
  85. GRB 210905A: ATCA detection
  86. GRB 210905A: ALMA detection
  87. GRB 210905A: AstroSat CZTI detection
  88. GRB 210905A, GROND observations
  89. Konus-Wind detection of GRB 210905A
  90. Fermi GBM Sub-Threshold Detection of GRB 210905A
  91. Fermi GBM trigger 652585475 / 210906073 is not a GRB
  92. Fermi trigger No 652585475: Global MASTER-Net observations report
  93. GRB 210905A: Swift-XRT refined Analysis
  94. GRB 210610A: Maidanak and AbAO optical observations
  95. GRB 210827B: GECAM detection
  96. GRB 210905A: DECam Detection
  97. GRB 210905A: REM NIR afterglow detection
  98. GRB 210905A: VLT/X-shooter spectroscopic redshift
  99. GRB 210905A: Continued LCO Optical Observations
  100. GRB 210905A: LCO Optical Detection

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