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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. Fermi GRB 200522B: Global MASTER-Net observations report
  2. GRB 200522B: Fermi GBM Final Real-time Localization
  3. GRB 200522A: Enhanced Swift-XRT position
  4. GRB 200522A: Coincident catalogued galaxy at z~0.4
  5. GRB 200522A: Swift detection of a short burst
  6. GRB 200521A: CALET Gamma-Ray Burst Monitor detection
  7. GRB 200521A: AGILE/MCAL and ratemeters detection
  8. GRB 200517A: Swift-XRT Confirmation of afterglow
  9. GRB 200514B: Fermi GBM observation
  10. GRB 200519A: CALET Gamma-Ray Burst Monitor detection
  11. GRB 200519A: R-band follow-up from HCT
  12. GRB 200519A: Swift-BAT refined analysis
  13. GRB 200519A: Insight-HXMT/HE detection
  14. GRB 200519A: Swift/UVOT Detection
  15. Fermi trigger No 611676654: Global MASTER-Net observations report
  16. GRB 200519A: GROWTH-India optical follow-up
  17. GRB 200519A: AstroSat CZTI detection
  18. Swift GRB 200519A: Global MASTER-Net observations report
  19. GRB 200519A: 1.3m DFOT Optical Afterglow Detection
  20. GRB 200519A: Swift-XRT refined Analysis
  21. Fermi trigger No 611605955: Global MASTER-Net observations report
  22. GRB 200519A: Enhanced Swift-XRT position
  23. GRB 200519A: BOOTES-3/YA optical counterpart observations
  24. GRB 200519A: LCO Optical Afterglow Detection
  25. Fermi GBM Sub-Threshold Detection of GRB 200517A
  26. GRB 200519A: iTelescope optical afterglow detection
  27. GRB 200519A: Swift detection of a burst with an optical afterglow
  28. IPN triangulation of GRB 200514B (short)
  29. GRB 200517A: Swift-XRT afterglow detection
  30. GRB 200514A: AstroSat CZTI detection
  31. Fermi trigger No 611434353: Global MASTER-Net observations report
  32. GRB 200517A: Tiled Swift observations
  33. GRB 200517A: MAXI/GSC detection
  34. Swift J1818.0-1607: BOOTES-3/YA optical upper limit
  35. GRB 200514B: BALROG localization (Fermi Trigger 611140062 / GRB 200514380)
  36. Swift GRB200516.63: Global MASTER-Net observations report
  37. Swift Detection of a burst from SGR Swift J1818.0-1607
  38. GRB 200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062) - More Candidates
  39. GRB 200514A: MITSuME Akeno optical upper limits
  40. GRB 200514A: CALET Gamma-Ray Burst Monitor detection
  41. GRB 200512A: Swift-BAT refined analysis
  42. GRB200514B: YSE detection of ZTF20aazpphd
  43. Optical transient ZTF20aazpphd is unrelated to GRB 200514B
  44. GRB 200514B: GROWTH-India follow-up of ZTF20aazpphd (AT2020jww)
  45. GRB200514B: ATLAS detections of ZTF20aazpphd
  46. GRB200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062)
  47. GRB 200514B: Fermi GBM Final Real-time Localization
  48. GRB 200514A: MAXI/GSC detection
  49. Baksan Neutrino Observatory Alert 200512.: Global MASTER-Net observations report
  50. GRB 200512A: LCO Optical Upper Limits
  51. IceCube-200512A: Upper limits from a search for additional neutrino events in IceCube
  52. Fermi GBM Sub-Threshold Detection of GRB 200512A
  53. GRB 200512A: Swift/UVOT Upper Limits
  54. GRB 200512A: Swift-XRT refined Analysis
  55. GRB 200512A: Enhanced Swift-XRT position
  56. AGILE detection of a burst from SGR 1935+2154 on May 10, 2020
  57. GRB 200512A: Swift detection of a burst
  58. Fermi-LAT Gamma-ray Observations of IceCube-200512A
  59. SGR 1935+2154: AstroSat CZTI detection
  60. IceCube-200512A: not observable by Fermi-GBM
  61. IceCube Alert 200512.31: Global MASTER-Net observations report
  62. IceCube-200512A: No Candidate Counterparts from the Zwicky Transient Facility
  63. IceCube-200512A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  64. IceCube-200512A: IceCube observation of a high-energy neutrino candidate event
  65. Insight-HXMT's continued observation plan for SGR J1935+2154
  66. Baksan Neutrino Observatory Alert 200511.76: Global MASTER-Net observations report
  67. GRB 200510A: AstroSat CZTI detection
  68. Konus-Wind observation of SGR 1935+2154 activity on 2020 May 10
  69. IPN triangulation of a bright burst from SGR 1935+2154 on 2020-05-10 at 06:12 UT
  70. GRB 200509A: Swift-BAT refined analysis
  71. GRB 200510A: BALROG localization (Fermi Trigger 610800081 / GRB 200510445)
  72. GRB 200510A: Fermi GBM Final Real-time Localization
  73. GRB 200509A: GROWTH-India r band upper limits
  74. GRB 200509A: Swift/UVOT Detection
  75. GRB 200509C: Fermi GBM Final Real-time Localization
  76. GRB 200509B: Fermi GBM Final Real-time Localization
  77. Swift GRB 200509A: Global MASTER-Net observations report
  78. GRB 200509A: LCO Optical Afterglow Detection
  79. GRB 200509A: Swift-XRT refined Analysis
  80. GRB 200509A: Enhanced Swift-XRT position
  81. GRB 200509A: Zadko observatory - Gingin optical upper limits
  82. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  83. FRB/X-ray bursts from SGR 1935+2154: No Neutrino Counterpart in ANTARES data
  84. GRB 200507A: Fermi GBM Final Real-time Localization
  85. GRB 200506A: AstroSat CZTI detection
  86. GRB 200506C: AstroSat CZTI detection
  87. Swift Detection of a burst from SGR Swift J1818.0-1607
  88. Swift GRB200506.73: Global MASTER-Net observations report
  89. GRB 200422A: INTEGRAL observations
  90. GRB 200505A: AGILE detection
  91. GRB 200506C: Fermi GBM Final Real-time Localization
  92. GRB 200506B: Fermi GBM Final Real-time Localization
  93. GRB 200506A: Fermi GBM Final Real-time Localization
  94. GRB 200505A: Fermi GBM Final Real-time Localization
  95. Insight-HXMT detection of a short bright burst from SGR 1935+2154
  96. AGILE detection of a short and hard X-ray burst possibly related to SGR 1935+2154
  97. GRB 200502A: AstroSat CZTI detection
  98. GRB 200503A: AGILE observations
  99. GRB 200502A: AGILE observations
  100. GRB 200503B: BALROG localization (Fermi Trigger 610219118 / GRB 200503721)

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