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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. GRB 200524A: Liverpool Telescope observations
  2. GRB 200524A: Correction to the GCN 27800
  3. GRB 200524A: 3.6m DOT observations of the afterglow candidate ZTF20abbiixp
  4. GRB 200524A: CrAO observations of ZTF20abbiixp
  5. Fermi GRB 200524A: Global MASTER-Net observations report
  6. GRB 200524A: GROWTH-India confirmation of optical afterglow
  7. ZTF Discovery of ZTF20abbiixp: The Likely Optical Afterglow to GRB 200524A
  8. GRB 200524A: Swift ToO observations
  9. GRB 200524A: Fermi-LAT detection
  10. Konus-Wind detection of short/hard GRB 200521A
  11. IPN triangulation of GRB 200521A (short)
  12. GRB 200522A: Correction to GCN 27792
  13. GRB 200522A: Swift-BAT refined analysis
  14. GRB 200522A: LCO Optical Afterglow Detection
  15. IceCube-200523A: Upper limits from Fermi-GBM Observations
  16. CGBM-SPI-ACS triangulation of short GRB 200521A
  17. Swift GRB 200522A: Global MASTER-Net observations report
  18. IceCube Alert 200523.10: Global MASTER-Net observations report
  19. IceCube-200523A - IceCube observation of a high-energy neutrino candidate event
  20. GRB 200522A: 6 GHz VLA radio source detection
  21. GRB 200522A: Swift-XRT refined Analysis
  22. GRB 200522A: BOOTES-3/YA optical upper limit
  23. GRB 200522A: Swift/UVOT Upper Limits
  24. Fermi GRB 200522B: Global MASTER-Net observations report
  25. GRB 200522B: Fermi GBM Final Real-time Localization
  26. GRB 200522A: Enhanced Swift-XRT position
  27. GRB 200522A: Coincident catalogued galaxy at z~0.4
  28. GRB 200522A: Swift detection of a short burst
  29. GRB 200521A: CALET Gamma-Ray Burst Monitor detection
  30. GRB 200521A: AGILE/MCAL and ratemeters detection
  31. GRB 200517A: Swift-XRT Confirmation of afterglow
  32. GRB 200514B: Fermi GBM observation
  33. GRB 200519A: CALET Gamma-Ray Burst Monitor detection
  34. GRB 200519A: R-band follow-up from HCT
  35. GRB 200519A: Swift-BAT refined analysis
  36. GRB 200519A: Insight-HXMT/HE detection
  37. GRB 200519A: Swift/UVOT Detection
  38. Fermi trigger No 611676654: Global MASTER-Net observations report
  39. GRB 200519A: GROWTH-India optical follow-up
  40. GRB 200519A: AstroSat CZTI detection
  41. Swift GRB 200519A: Global MASTER-Net observations report
  42. GRB 200519A: 1.3m DFOT Optical Afterglow Detection
  43. GRB 200519A: Swift-XRT refined Analysis
  44. Fermi trigger No 611605955: Global MASTER-Net observations report
  45. GRB 200519A: Enhanced Swift-XRT position
  46. GRB 200519A: BOOTES-3/YA optical counterpart observations
  47. GRB 200519A: LCO Optical Afterglow Detection
  48. Fermi GBM Sub-Threshold Detection of GRB 200517A
  49. GRB 200519A: iTelescope optical afterglow detection
  50. GRB 200519A: Swift detection of a burst with an optical afterglow
  51. IPN triangulation of GRB 200514B (short)
  52. GRB 200517A: Swift-XRT afterglow detection
  53. GRB 200514A: AstroSat CZTI detection
  54. Fermi trigger No 611434353: Global MASTER-Net observations report
  55. GRB 200517A: Tiled Swift observations
  56. GRB 200517A: MAXI/GSC detection
  57. Swift J1818.0-1607: BOOTES-3/YA optical upper limit
  58. GRB 200514B: BALROG localization (Fermi Trigger 611140062 / GRB 200514380)
  59. Swift GRB200516.63: Global MASTER-Net observations report
  60. Swift Detection of a burst from SGR Swift J1818.0-1607
  61. GRB 200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062) - More Candidates
  62. GRB 200514A: MITSuME Akeno optical upper limits
  63. GRB 200514A: CALET Gamma-Ray Burst Monitor detection
  64. GRB 200512A: Swift-BAT refined analysis
  65. GRB200514B: YSE detection of ZTF20aazpphd
  66. Optical transient ZTF20aazpphd is unrelated to GRB 200514B
  67. GRB 200514B: GROWTH-India follow-up of ZTF20aazpphd (AT2020jww)
  68. GRB200514B: ATLAS detections of ZTF20aazpphd
  69. GRB200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062)
  70. GRB 200514B: Fermi GBM Final Real-time Localization
  71. GRB 200514A: MAXI/GSC detection
  72. Baksan Neutrino Observatory Alert 200512.: Global MASTER-Net observations report
  73. GRB 200512A: LCO Optical Upper Limits
  74. IceCube-200512A: Upper limits from a search for additional neutrino events in IceCube
  75. Fermi GBM Sub-Threshold Detection of GRB 200512A
  76. GRB 200512A: Swift/UVOT Upper Limits
  77. GRB 200512A: Swift-XRT refined Analysis
  78. GRB 200512A: Enhanced Swift-XRT position
  79. AGILE detection of a burst from SGR 1935+2154 on May 10, 2020
  80. GRB 200512A: Swift detection of a burst
  81. Fermi-LAT Gamma-ray Observations of IceCube-200512A
  82. SGR 1935+2154: AstroSat CZTI detection
  83. IceCube-200512A: not observable by Fermi-GBM
  84. IceCube Alert 200512.31: Global MASTER-Net observations report
  85. IceCube-200512A: No Candidate Counterparts from the Zwicky Transient Facility
  86. IceCube-200512A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  87. IceCube-200512A: IceCube observation of a high-energy neutrino candidate event
  88. Insight-HXMT's continued observation plan for SGR J1935+2154
  89. Baksan Neutrino Observatory Alert 200511.76: Global MASTER-Net observations report
  90. GRB 200510A: AstroSat CZTI detection
  91. Konus-Wind observation of SGR 1935+2154 activity on 2020 May 10
  92. IPN triangulation of a bright burst from SGR 1935+2154 on 2020-05-10 at 06:12 UT
  93. GRB 200509A: Swift-BAT refined analysis
  94. GRB 200510A: BALROG localization (Fermi Trigger 610800081 / GRB 200510445)
  95. GRB 200510A: Fermi GBM Final Real-time Localization
  96. GRB 200509A: GROWTH-India r band upper limits
  97. GRB 200509A: Swift/UVOT Detection
  98. GRB 200509C: Fermi GBM Final Real-time Localization
  99. GRB 200509B: Fermi GBM Final Real-time Localization
  100. Swift GRB 200509A: Global MASTER-Net observations report

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