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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 200412B: Fermi GBM Final Real-time Localization
  2. GRB 200412A: BALROG localization (Fermi Trigger 608367436 / GRB 200412290)
  3. GRB 200411A: Swift-BAT refined analysis
  4. Fermi-LAT Gamma-ray Observations of IceCube-200410A
  5. GRB 200411A: Fermi GBM observation
  6. Swift GRB 200411A: Global MASTER-Net observations report
  7. IceCube-200410A: Upper limits from Fermi-GBM Observations
  8. GRB 200411A: Swift-XRT refined Analysis
  9. GRB 200411A: Swift/UVOT Upper Limits
  10. GRB 200411A: Enhanced Swift-XRT position
  11. IceCube-200410A: Possible associated excess in INTEGRAL SPI-ACS prompt observation
  12. GRB 200411A: Swift detection of a short burst
  13. GRB 200411A: Fermi GBM Final Real-time Localization
  14. IceCube-200410A - IceCube observation of a high-energy neutrino candidate event
  15. IceCube Alert 200410.97: Global MASTER-Net observations report
  16. GRB 200410A: Swift/UVOT Detection
  17. SGR 1935+2154: Fermi GBM observation
  18. Baksan Neutrino Observatory Alert 200410.82: Global MASTER-Net observations report
  19. Fermi trigger No 608204639: Global MASTER-Net observations report
  20. Baksan Neutrino Observatory Alert 200409.81: Global MASTER-Net observations report
  21. IPN Triangulation of a bright burst from SGR 1935+2154
  22. LIGO/Virgo S200225q: Swift XRT observations, 1 X-ray sources
  23. Konus-Wind observation of GRB 200327A
  24. LIGO/Virgo S200224ca: Swift XRT observations, 8 X-ray sources
  25. GRB 200410A: Swift-XRT refined Analysis
  26. GRB 200410A: Enhanced Swift-XRT position
  27. GRB 200409A: No detection of radio emission 5 hours post-burst
  28. GRB 200410A: Ondrejov D50 afterglow confirmation
  29. GRB 200409A: Swift-BAT refined analysis
  30. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  31. Swift GRB200410.10: Global MASTER-Net observations report
  32. GRB 200405B: ATCA follow-up and ASKAP limits on pre-burst radio emission
  33. Baksan Neutrino Observatory Alert 200408.26: Global MASTER-Net observations report
  34. Fermi GBM Sub-Threshold Detection of GRB 200409A
  35. Baksan Neutrino Observatory Alert 200409.23: Global MASTER-Net observations report
  36. Swift GRB 200409A: Global MASTER-Net observations report
  37. GRB 200409A: Swift-XRT refined Analysis
  38. GRB 200409A: Enhanced Swift-XRT position
  39. GRB 200409A: Swift detection of a burst with an optical counterpart
  40. Fermi GRB 200407A: Global MASTER-Net observations report
  41. Fermi GRB 200407B: Global MASTER-Net observations report
  42. IPN triangulation of GRB 200407A (short)
  43. IPN triangulation of GRB 200405B (short)
  44. Baksan Neutrino Observatory Alert 200406.3: Global MASTER-Net observations report
  45. GRB 200407B: Fermi GBM Final Real-time Localization
  46. GRB 200407A: Fermi GBM Final Real-time Localization
  47. GRB 200405B: LCO Optical Upper Limits
  48. GRB 200405B: Swift-XRT observations
  49. GRB 200405B: Swift ToO observations
  50. Fermi GRB 200405A: Global MASTER-Net observations report
  51. GRB 200405B: Swift/BAT-GUANO detection and *possible* arcminute localization of a short GRB
  52. GRB 200405A: Fermi GBM Final Real-time Localization
  53. GRB 200404A: Fermi GBM Final Localization
  54. Fermi GRB 200403C: Global MASTER-Net observations report
  55. GRB 200404A: BALROG localization (Fermi Trigger 607712227 / GRB 200404706)
  56. GRB 200403A: AstroSat CZTI detection
  57. Fermi GRB 200403B: Global MASTER-Net observations report
  58. Fermi GRB 200403A: Global MASTER-Net observations report
  59. GRB 200403C: Fermi GBM Final Real-time Localization
  60. LIGO/Virgo S200316bj: Upper limits from Konus-Wind observations
  61. LIGO/Virgo S200311bg: Upper limits from Konus-Wind observations
  62. LIGO/Virgo S200302c: Upper limits from Konus-Wind observations
  63. LIGO/Virgo S200225q: Upper limits from Konus-Wind observations
  64. GRB 200403B: Fermi GBM Final Real-time Localization
  65. LIGO/Virgo S200224ca: Upper limits from Konus-Wind observations
  66. GRB 200403A: Fermi GBM Final Real-time Localization
  67. GRB 200325B: Mondy continued observations
  68. Fermi GRB 200402C: Global MASTER-Net observations report
  69. GRB 200402C: Fermi GBM Final Localization
  70. GRB 200402B: Fermi GBM Final Localization
  71. Fermi trigger No 607537834: Global MASTER-Net observations report
  72. GRB 200402B: BALROG localization (Fermi Trigger 607537834 / GRB 200402688)
  73. Fermi GRB 200402A: Global MASTER-Net observations report
  74. GRB 200402A: BALROG localization (Fermi Trigger 607513182 / GRB 200402403)
  75. GRB 200325B: Optical upper limit
  76. GRB 200402A: Fermi GBM Final Real-time Localization
  77. GRB 200325B: further Swift-XRT observations
  78. Fermi GRB 200401A: Global MASTER-Net observations report
  79. GRB 200401A: Fermi GBM Final Real-time Localization
  80. GRB 200325B: Mondy continued observations
  81. GRB 200325B: Mondy continued observations
  82. GRB 200327A: Fermi GBM detection
  83. GRB 200325B: Mondy continued observations
  84. GRB 200325B: Tautenburg observations
  85. IPN triangulation of GRB 200327A (short)
  86. GRB 200326B: AstroSat CZTI detection
  87. GRB 200327A: AGILE/MCAL observations
  88. GRB 200325B: Fermi GBM observation
  89. Fermi trigger No 607035413: Global MASTER-Net observations report
  90. GRB 200327A: Fermi GBM Final Real-time Localization
  91. GRB 200325B: Swift-XRT and UVOT observations
  92. GRB 200325B: LCO Optical Detection
  93. GRB 200325B: Mondy, CrAO, AbAO afterglow confirmation and refined photometry of MASTER OT J111012.51+274912.8
  94. GRB 200326B: AstroSat LAXPC detection
  95. GRB 200325A: Fermi GBM observation
  96. GRB 200325B: Mondy and CrAO observations, Master MASTER OT J111012.51+274912.8 confirmation
  97. Fermi trigger No 606918292: Global MASTER-Net observations report
  98. GRB 200325B: Swift ToO observations
  99. IPN triangulation of GRB 200325A (short)
  100. Fermi trigger No 606799116: Global MASTER-Net observations report

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