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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 200522A: Gemini North optical imaging
  2. GRB 200524A: CrAO optical observations
  3. GRB 200524A: Kitab observatory afterglow observations
  4. GRB 200525A: Fermi GBM Final Real-time Localization
  5. GRB 200524A: AstroSat CZTI detection
  6. GRB 200524A: Further Liverpool Telescope observations
  7. Fermi-LAT Gamma-ray Observations of IceCube-190523A
  8. GRB200521A: ASIM observation
  9. GRB 200524A: KAIT Optical Observations
  10. GRB 200524A: MITSuME Akeno optical observation
  11. GRB 171205A: ATCA observations of late-time radio emission
  12. GRB 200524A: Swift-XRT afterglow detection
  13. GRB 200524A: OAJ multicolor afterglow detection
  14. GRB 200524A: Fermi GBM detection
  15. GRB 200524: Swift/UVOT observations missed the ZTF20abbiixp position
  16. GRB 200524A: CAHA multicolor afterglow detection
  17. GRB 200524A: 1.3m DFOT Optical Observation of ZTF20abbiixp
  18. GRB 200524A: Liverpool Telescope observations
  19. GRB 200524A: Correction to the GCN 27800
  20. GRB 200524A: 3.6m DOT observations of the afterglow candidate ZTF20abbiixp
  21. GRB 200524A: CrAO observations of ZTF20abbiixp
  22. Fermi GRB 200524A: Global MASTER-Net observations report
  23. GRB 200524A: GROWTH-India confirmation of optical afterglow
  24. ZTF Discovery of ZTF20abbiixp: The Likely Optical Afterglow to GRB 200524A
  25. GRB 200524A: Swift ToO observations
  26. GRB 200524A: Fermi-LAT detection
  27. Konus-Wind detection of short/hard GRB 200521A
  28. IPN triangulation of GRB 200521A (short)
  29. GRB 200522A: Correction to GCN 27792
  30. GRB 200522A: Swift-BAT refined analysis
  31. GRB 200522A: LCO Optical Afterglow Detection
  32. IceCube-200523A: Upper limits from Fermi-GBM Observations
  33. CGBM-SPI-ACS triangulation of short GRB 200521A
  34. Swift GRB 200522A: Global MASTER-Net observations report
  35. IceCube Alert 200523.10: Global MASTER-Net observations report
  36. IceCube-200523A - IceCube observation of a high-energy neutrino candidate event
  37. GRB 200522A: 6 GHz VLA radio source detection
  38. GRB 200522A: Swift-XRT refined Analysis
  39. GRB 200522A: BOOTES-3/YA optical upper limit
  40. GRB 200522A: Swift/UVOT Upper Limits
  41. Fermi GRB 200522B: Global MASTER-Net observations report
  42. GRB 200522B: Fermi GBM Final Real-time Localization
  43. GRB 200522A: Enhanced Swift-XRT position
  44. GRB 200522A: Coincident catalogued galaxy at z~0.4
  45. GRB 200522A: Swift detection of a short burst
  46. GRB 200521A: CALET Gamma-Ray Burst Monitor detection
  47. GRB 200521A: AGILE/MCAL and ratemeters detection
  48. GRB 200517A: Swift-XRT Confirmation of afterglow
  49. GRB 200514B: Fermi GBM observation
  50. GRB 200519A: CALET Gamma-Ray Burst Monitor detection
  51. GRB 200519A: R-band follow-up from HCT
  52. GRB 200519A: Swift-BAT refined analysis
  53. GRB 200519A: Insight-HXMT/HE detection
  54. GRB 200519A: Swift/UVOT Detection
  55. Fermi trigger No 611676654: Global MASTER-Net observations report
  56. GRB 200519A: GROWTH-India optical follow-up
  57. GRB 200519A: AstroSat CZTI detection
  58. Swift GRB 200519A: Global MASTER-Net observations report
  59. GRB 200519A: 1.3m DFOT Optical Afterglow Detection
  60. GRB 200519A: Swift-XRT refined Analysis
  61. Fermi trigger No 611605955: Global MASTER-Net observations report
  62. GRB 200519A: Enhanced Swift-XRT position
  63. GRB 200519A: BOOTES-3/YA optical counterpart observations
  64. GRB 200519A: LCO Optical Afterglow Detection
  65. Fermi GBM Sub-Threshold Detection of GRB 200517A
  66. GRB 200519A: iTelescope optical afterglow detection
  67. GRB 200519A: Swift detection of a burst with an optical afterglow
  68. IPN triangulation of GRB 200514B (short)
  69. GRB 200517A: Swift-XRT afterglow detection
  70. GRB 200514A: AstroSat CZTI detection
  71. Fermi trigger No 611434353: Global MASTER-Net observations report
  72. GRB 200517A: Tiled Swift observations
  73. GRB 200517A: MAXI/GSC detection
  74. Swift J1818.0-1607: BOOTES-3/YA optical upper limit
  75. GRB 200514B: BALROG localization (Fermi Trigger 611140062 / GRB 200514380)
  76. Swift GRB200516.63: Global MASTER-Net observations report
  77. Swift Detection of a burst from SGR Swift J1818.0-1607
  78. GRB 200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062) - More Candidates
  79. GRB 200514A: MITSuME Akeno optical upper limits
  80. GRB 200514A: CALET Gamma-Ray Burst Monitor detection
  81. GRB 200512A: Swift-BAT refined analysis
  82. GRB200514B: YSE detection of ZTF20aazpphd
  83. Optical transient ZTF20aazpphd is unrelated to GRB 200514B
  84. GRB 200514B: GROWTH-India follow-up of ZTF20aazpphd (AT2020jww)
  85. GRB200514B: ATLAS detections of ZTF20aazpphd
  86. GRB200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062)
  87. GRB 200514B: Fermi GBM Final Real-time Localization
  88. GRB 200514A: MAXI/GSC detection
  89. Baksan Neutrino Observatory Alert 200512.: Global MASTER-Net observations report
  90. GRB 200512A: LCO Optical Upper Limits
  91. IceCube-200512A: Upper limits from a search for additional neutrino events in IceCube
  92. Fermi GBM Sub-Threshold Detection of GRB 200512A
  93. GRB 200512A: Swift/UVOT Upper Limits
  94. GRB 200512A: Swift-XRT refined Analysis
  95. GRB 200512A: Enhanced Swift-XRT position
  96. AGILE detection of a burst from SGR 1935+2154 on May 10, 2020
  97. GRB 200512A: Swift detection of a burst
  98. Fermi-LAT Gamma-ray Observations of IceCube-200512A
  99. SGR 1935+2154: AstroSat CZTI detection
  100. IceCube-200512A: not observable by Fermi-GBM

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