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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. Konus-Wind detection of GRB 210928A
  2. Fermi trigger No 654854799: Global MASTER-Net observations report
  3. Correction to GCN 30915: GRB 210928A: Swift-XRT analysis
  4. GRB 210928A: Kinder SLT-40cm optical limits
  5. GRB 210930A: Swift-BAT refined analysis
  6. SGR 1935+2154: Swift/BAT-GUANO detection and arcminute localization
  7. GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
  8. GRB 210928A: Swift-XRT refined Analysis
  9. GRB 210928A: Fermi GBM observation
  10. GRB 210928A: Fermi-LAT detection
  11. Swift GRB211001.03 / trigger 1076121 : MASTER OT retraction
  12. GRB 210927B: GECAM detection
  13. GRB 210930A: CAHA 2.2m telescope optical limit
  14. GRB 210927A: GIT optical follow-up of ZTF21acdwctm.
  15. Fermi trigger No 654739449: Global MASTER-Net observations report
  16. Swift GRB211001.03: Global MASTER-Net observations report
  17. Swift Trigger 1076121 is not a GRB
  18. Swift GRB211001.03: Global MASTER-Net OT detection
  19. GRB 210930A: Swift/UVOT Upper Limits
  20. GRB 210930A: Swift-XRT refined Analysis
  21. Swift GRB 210930A: Global MASTER-Net observations report
  22. GRB 210930A: Enhanced Swift-XRT position
  23. Fermi trigger No 654658271: Global MASTER-Net observations report
  24. Fermi GRB 210929B: Global MASTER-Net observations report
  25. GRB 210930A: Swift detection of a burst
  26. GRB 210929B: Fermi GBM Final Real-time Localization
  27. Fermi-LAT Gamma-ray Observations of IceCubeCascade-210926A
  28. GRB 210929A: Fermi GBM Final Real-time Localization
  29. GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
  30. GRB 210925B: AstroSat CZTI detection
  31. IceCube-210922A: SMA observation for the JCMT candidate
  32. IPN triangulation of GRB 210925B
  33. GRB 210926A: AstroSat CZTI detection
  34. GRB 210919A: iTelescope T-11 upper limits
  35. IceCube-210926A: No neutrino counterpart candidates in ANTARES search
  36. GRB 210926A: GECAM detection
  37. GRB 210927A: Fermi GBM Final Real-time Localization
  38. GRB 210919A OSN 1.5m Source Confirmation
  39. GRB 210919A CAHA 2.2m Observations: Afterglow/Host Galaxy Candidate
  40. IceCube-210922A: JCMT/SCUBA2 observations
  41. GRB 210925A: GECAM detection
  42. GRB 210925A: Fermi GBM Final Real-time Localization
  43. GRB 210919A: Chandra rapid ToO upper limit
  44. GRB 210924A: Fermi GBM Final Real-time Localization
  45. IceCube-210922A: No Candidate Counterparts from Swift/XRT follow up observations
  46. IceCube-210922A: No significant detection in HAWC
  47. IceCube-210922A: No neutrino counterpart candidates in ANTARES search
  48. GRB 210923B: GECAM detection
  49. Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB
  50. IceCube-210922A: Upper limits from a search for additional neutrino events in IceCube
  51. IceCube-210922A: Upper limits from Fermi-GBM Observations
  52. IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility
  53. GECAM observations of a series of bursts from SGR J1935+2154 (2021-09-15T14 to 2021-09-23T14)
  54. GRB 210919A: DECam Upper Limits
  55. Fermi-LAT Gamma-ray Observations of IceCube-210922A
  56. Konus-Wind detection of a burst from SGR 1935+2154 on 2021 September 22
  57. GRB 210923A: Fermi GBM Final Real-time Localization
  58. IceCube Alert 210922.76: Global MASTER-Net observations report
  59. GRB 210919A: Swift-BAT refined analysis
  60. IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 210912A: LBT optical observations
  62. GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
  63. GRB 210919a: Lowell Discovery Telescope upper limits
  64. GRB210919A: Keck NIRC2 Kp band upper limits
  65. GRB 210919A: Swift/UVOT Upper Limits
  66. GRB 210919A: LOAO and LSGT optical upper limits
  67. GRB 210919A: MITSuME Akeno optical upper limits
  68. GRB 210919A: Swift-XRT refined Analysis
  69. GRB 210919B: Fermi GBM Final Real-time Localization
  70. GRB 210919A: NOT upper limits
  71. GRB 210919A: AbAO optical upper limit
  72. GRB 210919A: Enhanced Swift-XRT position
  73. GRB 210919A: LCO Optical Upper Limit
  74. GRB 210919A: BOOTES-2/TELMA optical upper limit
  75. Swift GRB 210919A: Global MASTER-Net observations report
  76. GRB 210919A: Swift detection of a short burst
  77. Swift trigger 1073821: detection of IGR J16418-4532
  78. GRB 210912A: BOOTES-5/JGT optical afterglow candidate (Correction to GCNC 30823)
  79. GRB 210917A: Fermi GBM Final Real-time Localization
  80. GRB 210812A is not a compelling example of a lensed GRB
  81. GECAM observations of bursts from SGR J1935+2154 (2021-09-13T01 to 2021-09-15T14)
  82. GRB 210909A: Detection by GRBAlpha
  83. GRB 210912A: Swift-BAT refined analysis
  84. Konus-Wind observation of the recent SGR 1935+2154 activity
  85. GRB 210912A: Tautenburg observations
  86. GECAM observations of bursts from SGR J1935+2154 (2021-09-12T05 to 2021-09-13T01)
  87. AGILE observations of two bright bursts from SGR 1935+2154
  88. GRB 210912A: CAHA 2.2m Detection
  89. GRB 210912A: Swift-XRT refined Analysis
  90. GRB 210912A: Swift/UVOT Detection
  91. Fermi GBM observation of another bright burst in the direction of SGR 1935+2154
  92. GRB 210912A: Enhanced Swift-XRT position
  93. GRB 210912A: Host-galaxy candidate in PanSTARRS
  94. Fermi trigger No 653151835: Global MASTER-Net observations report
  95. Fermi trigger No 653124492: Global MASTER-Net observations report
  96. Fermi trigger No 653122278: Global MASTER-Net observations report
  97. GRB 210912A: Mondy optical afterglow confirmation
  98. Swift GRB 210912A: Global MASTER-Net observations report
  99. GRB 210912A: BOOTES-5/JGT optical afterglow candidate
  100. GECAM observations of bursts from SGR J1935+2154 (2021-09-11T07 to 2021-09-12T08)

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