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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. IPN triangulation of GRB 220130A
  2. Swift Reaction Wheel Anomaly Update (4 Feb 2022)
  3. Fermi-LAT Gamma-ray Observations of IceCube-220202A
  4. IceCube-220202A: Upper limits from a search for additional neutrino events in IceCube
  5. GRB 211227A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  6. IceCube-220202A: IceCube observation of a high-energy neutrino candidate track-like event
  7. IceCube Alert 220202.49: Global MASTER-Net observations report
  8. GRB 220131B: Swift/BAT-GUANO detection outside the coded FOV
  9. GRB 220201A: Fermi GBM Final Localization
  10. GRB 220128A: AstroSat CZTI detection
  11. GRB 220130A: Fermi GBM Observation
  12. Konus-Wind detection of GRB 220128A
  13. IPN triangulation of GRB 220128A (long)
  14. Fermi GRB 220131A: Global MASTER-Net observations report
  15. GRB 220131B: GECAM detection
  16. GRB 220130A: GECAM detection
  17. GRB 220131A: Fermi GBM Final Real-time Localization
  18. Fermi GRB 220129A: Global MASTER-Net observations report
  19. GRB 220129A: Fermi GBM Final Real-time Localization
  20. IceCube-211208A: the optical observation of the candidate PKS0735+178
  21. GRB 220127A: GECAM detection
  22. GECAM observations of a series of bursts from SGR J1935+2154
  23. Konus-Wind detection of GRB 220124A
  24. IPN triangulation of GRB 220124A
  25. GRB 220124A: GECAM detection
  26. Fermi trigger No 664738369: Global MASTER-Net observations report
  27. GRB 220117A, GROND observations
  28. GRB 220124A: AstroSat CZTI detection of a bright long GRB
  29. GRB 220117A: Terskol and AbAO optical upper limits
  30. GRB 220118A: TARGET optical upper limit
  31. GRB 220117B: TARGET optical upper limit
  32. GRB 220121B: GECAM detection
  33. Fermi-LAT-ANTARES 220121a: upper limits from a search for coincident neutrinos with IceCube
  34. AGILE observations of a bright burst from SGR 1935+2154
  35. Fermi-LAT-ANTARES 220121a Coincidence
  36. Konus-Wind detection of an intermediate flare from SGR 1935+2154 on January 20
  37. IPN triangulation of a bright burst from SGR 1935+2154
  38. GRB 220117A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  39. IPN triangulation of GRB 211226A
  40. GRB 220120A: Fermi GBM Final Localization
  41. GRB 220117C: Fermi GBM Observation
  42. GRB 220118A: 2.2m CAHA/CAFOS detections
  43. GRB 220118A: Fermi GBM detection
  44. GRB 220118A: COATLI Optical Observations
  45. GRB 220101A: KAO optical-R observation
  46. GRB 211221A: No V & R detection, KAO telescope
  47. GRB 220118A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  48. GRB 220117C: Swift/BAT-GUANO arcminute localization
  49. Swift currently in safe hold with science slews disabled
  50. GRB 220118A: Swift-BAT refined analysis
  51. GRB 220118A: Swift/UVOT Detection
  52. Konus-Wind observation of the recent SGR 1935+2154 activity
  53. GRB 220118A: GIT optical observations
  54. GRB 220118A: Enhanced Swift-XRT position
  55. Swift GRB220118.50: Global MASTER-Net observations report
  56. GRB 220118A: MITSuME Akeno optical observation
  57. GRB 220117B: z-band limit
  58. Swift GRB 220118A: Global MASTER-Net observations report
  59. GRB 220118A: Swift detection of a burst with an optical counterpart
  60. GRB 220118A: Fermi GBM Final Real-time Localization
  61. GRB 220117A: MITSuME Akeno optical upper limits
  62. Fermi GBM Sub-Threshold Detection of GRB 220117A
  63. GRB 220117B: Swift-BAT refined analysis
  64. GRB 220117A: Swift-BAT refined analysis
  65. IceCube-220115A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB 220117B: Swift/UVOT Upper Limits
  67. GRB 220117A: Swift/UVOT Upper Limits
  68. GRB 220117A: LCO Optical Observations
  69. GRB 220117A: VLT/X-shooter optical afterglow and redshift
  70. Fermi-LAT Gamma-ray Observations of IceCube-220115A and detection of a new gamma-ray source, Fermi J2350.2+2620
  71. GRB 220117B: Swift-XRT refined Analysis
  72. GRB 220117A: Swift-XRT refined Analysis
  73. AMON IC_HAWC NuEm-220116A: No neutrino counterpart detected with ANTARES
  74. GRB 220117B: Nanshan/NEXT optical upper limit
  75. GRB 220117B: MITSuME Akeno optical upper limits
  76. GRB 220117B: Enhanced Swift-XRT position
  77. GRB 220117A: Enhanced Swift-XRT position
  78. GRB 220101A: TSHAO optical observation, Terskol, AbAO upper limits
  79. Swift GRB 220117A: Global MASTER-Net observations report
  80. Swift GRB 220117B: Global MASTER-Net observations report
  81. GRB 220117B: Swift detection of a burst
  82. GRB 220117A: Nanshan/NEXT optical observations and a nearby PanSTARRS source
  83. GRB 220117A: Swift detection of a burst
  84. GRB 220101A: The most powerful GRB and BDHN I in 26 years
  85. GECAM observations of a series of bursts from SGR J1935+2154
  86. Fermi trigger No 663960124: Global MASTER-Net observations report
  87. Fermi trigger No 663967527: Global MASTER-Net observations report
  88. Fermi trigger No 663923149: Global MASTER-Net observations report
  89. Fermi trigger No 663899819: Global MASTER-Net observations report
  90. Fermi trigger No 663886592: Global MASTER-Net observations report
  91. Fermi trigger No 663966693: Global MASTER-Net observations report
  92. GRB 220115B: Fermi GBM Final Real-time Localization
  93. IceCube Alert 220115.51: Global MASTER-Net observations report
  94. Fermi trigger No 663927396: Global MASTER-Net observations report
  95. Fermi trigger No 663921434: Global MASTER-Net observations report
  96. GRB 210919A: LBT spectroscopic redshift of the host galaxy candidates
  97. GRB 220115A: Fermi GBM Final Real-time Localization
  98. IceCube-220115A - IceCube observation of a high-energy neutrino candidate track-like event
  99. Fermi Gamma-ray Burst Monitor trigger 663917434/220115230 is not a GRB
  100. GRB 220114A: Fermi GBM Final Localization

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