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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 220210A: Global MASTER-Net observations report
  2. GRB 220210A: Fermi GBM Final Real-time Localization
  3. GRB 210919A: Maidanak optical observations
  4. GRB 210919A: SPI-ACS/INTEGRAL observation and evaluation of Ep
  5. GRB 220209A: Fermi GBM Detection
  6. GRB 220209A: GECAM detection
  7. GRB 220209A: AGILE/MCAL detection
  8. Fermi GRB 220209A: Global MASTER-Net observations report
  9. GRB 220209A: Fermi GBM Final Real-time Localization
  10. IceCube-220205B: Upper limits from a search for additional neutrino events in IceCube
  11. IceCube-220205A: Upper limits from a search for additional neutrino events in IceCube
  12. Fermi-LAT Gamma-ray Observations of IceCube-220205B
  13. Fermi-LAT Gamma-ray Observations of IceCube-220205A
  14. IceCube-220205B: No neutrino counterpart candidates in ANTARES search
  15. Konus-Wind detection of GRB 220130A
  16. IceCube-220205B - IceCube observation of a high-energy neutrino candidate track-like event
  17. Konus-Wind detection of GRB 220203A
  18. GRB 220203A: GECAM detection
  19. IceCube-220205A - IceCube observation of a high-energy neutrino candidate track-like event
  20. GRB 220203A: Swift/BAT-GUANO detection outside the coded FOV
  21. IPN triangulation of GRB 220203A (short)
  22. IPN triangulation of GRB 220130A
  23. Swift Reaction Wheel Anomaly Update (4 Feb 2022)
  24. Fermi-LAT Gamma-ray Observations of IceCube-220202A
  25. IceCube-220202A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 211227A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  27. IceCube-220202A: IceCube observation of a high-energy neutrino candidate track-like event
  28. IceCube Alert 220202.49: Global MASTER-Net observations report
  29. GRB 220131B: Swift/BAT-GUANO detection outside the coded FOV
  30. GRB 220201A: Fermi GBM Final Localization
  31. GRB 220128A: AstroSat CZTI detection
  32. GRB 220130A: Fermi GBM Observation
  33. Konus-Wind detection of GRB 220128A
  34. IPN triangulation of GRB 220128A (long)
  35. Fermi GRB 220131A: Global MASTER-Net observations report
  36. GRB 220131B: GECAM detection
  37. GRB 220130A: GECAM detection
  38. GRB 220131A: Fermi GBM Final Real-time Localization
  39. Fermi GRB 220129A: Global MASTER-Net observations report
  40. GRB 220129A: Fermi GBM Final Real-time Localization
  41. IceCube-211208A: the optical observation of the candidate PKS0735+178
  42. GRB 220127A: GECAM detection
  43. GECAM observations of a series of bursts from SGR J1935+2154
  44. Konus-Wind detection of GRB 220124A
  45. IPN triangulation of GRB 220124A
  46. GRB 220124A: GECAM detection
  47. Fermi trigger No 664738369: Global MASTER-Net observations report
  48. GRB 220117A, GROND observations
  49. GRB 220124A: AstroSat CZTI detection of a bright long GRB
  50. GRB 220117A: Terskol and AbAO optical upper limits
  51. GRB 220118A: TARGET optical upper limit
  52. GRB 220117B: TARGET optical upper limit
  53. GRB 220121B: GECAM detection
  54. Fermi-LAT-ANTARES 220121a: upper limits from a search for coincident neutrinos with IceCube
  55. AGILE observations of a bright burst from SGR 1935+2154
  56. Fermi-LAT-ANTARES 220121a Coincidence
  57. Konus-Wind detection of an intermediate flare from SGR 1935+2154 on January 20
  58. IPN triangulation of a bright burst from SGR 1935+2154
  59. GRB 220117A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  60. IPN triangulation of GRB 211226A
  61. GRB 220120A: Fermi GBM Final Localization
  62. GRB 220117C: Fermi GBM Observation
  63. GRB 220118A: 2.2m CAHA/CAFOS detections
  64. GRB 220118A: Fermi GBM detection
  65. GRB 220118A: COATLI Optical Observations
  66. GRB 220101A: KAO optical-R observation
  67. GRB 211221A: No V & R detection, KAO telescope
  68. GRB 220118A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  69. GRB 220117C: Swift/BAT-GUANO arcminute localization
  70. Swift currently in safe hold with science slews disabled
  71. GRB 220118A: Swift-BAT refined analysis
  72. GRB 220118A: Swift/UVOT Detection
  73. Konus-Wind observation of the recent SGR 1935+2154 activity
  74. GRB 220118A: GIT optical observations
  75. GRB 220118A: Enhanced Swift-XRT position
  76. Swift GRB220118.50: Global MASTER-Net observations report
  77. GRB 220118A: MITSuME Akeno optical observation
  78. GRB 220117B: z-band limit
  79. Swift GRB 220118A: Global MASTER-Net observations report
  80. GRB 220118A: Swift detection of a burst with an optical counterpart
  81. GRB 220118A: Fermi GBM Final Real-time Localization
  82. GRB 220117A: MITSuME Akeno optical upper limits
  83. Fermi GBM Sub-Threshold Detection of GRB 220117A
  84. GRB 220117B: Swift-BAT refined analysis
  85. GRB 220117A: Swift-BAT refined analysis
  86. IceCube-220115A: Upper limits from a search for additional neutrino events in IceCube
  87. GRB 220117B: Swift/UVOT Upper Limits
  88. GRB 220117A: Swift/UVOT Upper Limits
  89. GRB 220117A: LCO Optical Observations
  90. GRB 220117A: VLT/X-shooter optical afterglow and redshift
  91. Fermi-LAT Gamma-ray Observations of IceCube-220115A and detection of a new gamma-ray source, Fermi J2350.2+2620
  92. GRB 220117B: Swift-XRT refined Analysis
  93. GRB 220117A: Swift-XRT refined Analysis
  94. AMON IC_HAWC NuEm-220116A: No neutrino counterpart detected with ANTARES
  95. GRB 220117B: Nanshan/NEXT optical upper limit
  96. GRB 220117B: MITSuME Akeno optical upper limits
  97. GRB 220117B: Enhanced Swift-XRT position
  98. GRB 220117A: Enhanced Swift-XRT position
  99. GRB 220101A: TSHAO optical observation, Terskol, AbAO upper limits
  100. Swift GRB 220117A: Global MASTER-Net observations report

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