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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. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  2. GRB 230405A: Fermi GBM Final Real-time Localization
  3. GRB 230404A: AstroSat CZTI detection
  4. GRB 230404A: Fermi GBM Final Real-time Localization
  5. GRB 230402A: CALET Gamma-Ray Burst Monitor detection
  6. GRB 230402A: AstroSat CZTI detection
  7. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  8. IceCube-230401A: Upper limits from a search for additional neutrino events in IceCube
  9. GRB 230328B: Multa observatory optical afterglow observation
  10. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  11. GRB 230228A: detection by GTC of the potential host galaxy
  12. GRB 230328B: Swift/UVOT Detection
  13. GRB 230402A: AGILE detection
  14. Fermi GRB 230402A: Global MASTER-Net observations report
  15. GRB 230402A: Fermi GBM Final Real-time Localization
  16. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  17. GRB 230307A: Bad Time Intervals for Fermi GBM data
  18. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  19. GRB 230328B: CAHA 2.2m/CAFOS detection
  20. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  21. GRB 230328B: 3.6m DOT multiband optical observation
  22. Fermi trigger No 701883729: Global MASTER-Net observations report
  23. GRB 230330B: Fermi GBM Final Localization
  24. Konus-Wind detection of GRB 230328B
  25. GRB 230328B: GRBAlpha detection
  26. GRB 230330A: Fermi GBM Final Real-time Localization
  27. GRB 230328B: Swift-BAT refined analysis
  28. GRB 230328B: Nanshan/NEXT 2nd optical observation
  29. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  30. GRB 230328B: Liverpool Telescope afterglow detection
  31. GRB 230328B: OHP/T120 optical observations
  32. GRB 230328B: GIT optical follow-up
  33. GRB 230328B: OASDG optical observations
  34. GRB 230328B: Nanshan/NEXT optical upper limit
  35. GRB 230328B: Swift-XRT refined Analysis
  36. GRB 230328B: AstroSat CZTI detection
  37. GRB 230328B: Fermi GBM observation
  38. GRB 230328B: Mondy, AbAO and Kitab optical observations
  39. GRB 230328B: Enhanced Swift-XRT position
  40. GRB 230328B: Mondy optical afterglow confirmation
  41. GRB 230328B: Swift detection of a burst with an optical afterglow
  42. GRB 230328B: Fermi GBM Final Real-time Localization
  43. Fermi GRB 230328A: Global MASTER-Net observations report
  44. GRB 230328A: Fermi GBM Final Real-time Localization
  45. GRB 230325A: Swift-BAT refined analysis
  46. GRB 230325A: Swift/UVOT Upper Limits
  47. GRB 230325A: X-shooter optical afterglow and redshift
  48. GRB 230325A: Swift-XRT refined Analysis
  49. GRB 230322B: Swift-BAT refined analysis
  50. GRB 230325A: Enhanced Swift-XRT position
  51. GRB 230325A: Prompt enhanced Swift-XRT position
  52. GRB 230325A: Swift detection of a burst
  53. GRB 230320B: Fermi GBM Observation
  54. Fermi trigger No 701313046: Global MASTER-Net observations report
  55. Fermi trigger No 701321709: Global MASTER-Net observations report
  56. GRB 230322B: Swift/UVOT Detection
  57. Konus-Wind detection of GRB 230309A
  58. Konus-Wind detection of GRB 230308A
  59. Konus-Wind detection of GRB 230304B
  60. GRB 230322B: Swift-XRT refined Analysis
  61. GRB 230322B: Enhanced Swift-XRT position
  62. Swift GRB 230322B: Global MASTER-Net observations report
  63. GRB 230322B: Swift detection of a burst with optical counterpart
  64. GRB 230322A: Fermi GBM Final Real-time Localization
  65. GRB 230320B: GRBAlpha detection
  66. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  68. Fermi trigger No 701071944: Global MASTER-Net observations report
  69. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  70. Fermi GRB 230320A: Global MASTER-Net observations report
  71. Fermi GRB 230321A: Global MASTER-Net observations report
  72. Fermi trigger No 701058254: Global MASTER-Net observations report
  73. SGR 1806-20: Correction to GCN 33494
  74. INTEGRAL detection of a burst from SGR 1806-200
  75. GRB 230321B: AstroSat CZTI detection
  76. GRB 230320B: AstroSat CZTI detection
  77. GRB 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
  78. GRB 230321A: Fermi GBM Final Real-time Localization
  79. GRB 230320A: Fermi GBM Final Real-time Localization
  80. GRB 230314A: TURBO Optical Upper Limit
  81. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  82. Fermi trigger No 700976129: Global MASTER-Net observations report
  83. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  84. IPN triangulation of GRB 230309A
  85. Fermi GRB 230316A: Global MASTER-Net observations report
  86. GRB 230304D: AstroSat CZTI detection
  87. GRB 230316A: Fermi GBM Final Real-time Localization
  88. IPN triangulation of GRB 230304B
  89. GRB 230313A: AstroSat CZTI detection
  90. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  91. IPN triangulation of GRB 230308A (short/bright)
  92. Fermi GRB 230314A: Global MASTER-Net observations report
  93. GRB 230307A: ATCA radio detection
  94. GRB 230314A: Fermi GBM Final Real-time Localization
  95. VZLUSAT-2 detection of SGR 1806-20
  96. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  97. GRB 230307A: Swift/UVOT detection
  98. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  99. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  100. Fermi GRB 230313A: Global MASTER-Net observations report

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