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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 230402A: Fermi GBM Final Real-time Localization
  2. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  3. GRB 230307A: Bad Time Intervals for Fermi GBM data
  4. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  5. GRB 230328B: CAHA 2.2m/CAFOS detection
  6. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 230328B: 3.6m DOT multiband optical observation
  8. Fermi trigger No 701883729: Global MASTER-Net observations report
  9. GRB 230330B: Fermi GBM Final Localization
  10. Konus-Wind detection of GRB 230328B
  11. GRB 230328B: GRBAlpha detection
  12. GRB 230330A: Fermi GBM Final Real-time Localization
  13. GRB 230328B: Swift-BAT refined analysis
  14. GRB 230328B: Nanshan/NEXT 2nd optical observation
  15. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  16. GRB 230328B: Liverpool Telescope afterglow detection
  17. GRB 230328B: OHP/T120 optical observations
  18. GRB 230328B: GIT optical follow-up
  19. GRB 230328B: OASDG optical observations
  20. GRB 230328B: Nanshan/NEXT optical upper limit
  21. GRB 230328B: Swift-XRT refined Analysis
  22. GRB 230328B: AstroSat CZTI detection
  23. GRB 230328B: Fermi GBM observation
  24. GRB 230328B: Mondy, AbAO and Kitab optical observations
  25. GRB 230328B: Enhanced Swift-XRT position
  26. GRB 230328B: Mondy optical afterglow confirmation
  27. GRB 230328B: Swift detection of a burst with an optical afterglow
  28. GRB 230328B: Fermi GBM Final Real-time Localization
  29. Fermi GRB 230328A: Global MASTER-Net observations report
  30. GRB 230328A: Fermi GBM Final Real-time Localization
  31. GRB 230325A: Swift-BAT refined analysis
  32. GRB 230325A: Swift/UVOT Upper Limits
  33. GRB 230325A: X-shooter optical afterglow and redshift
  34. GRB 230325A: Swift-XRT refined Analysis
  35. GRB 230322B: Swift-BAT refined analysis
  36. GRB 230325A: Enhanced Swift-XRT position
  37. GRB 230325A: Prompt enhanced Swift-XRT position
  38. GRB 230325A: Swift detection of a burst
  39. GRB 230320B: Fermi GBM Observation
  40. Fermi trigger No 701313046: Global MASTER-Net observations report
  41. Fermi trigger No 701321709: Global MASTER-Net observations report
  42. GRB 230322B: Swift/UVOT Detection
  43. Konus-Wind detection of GRB 230309A
  44. Konus-Wind detection of GRB 230308A
  45. Konus-Wind detection of GRB 230304B
  46. GRB 230322B: Swift-XRT refined Analysis
  47. GRB 230322B: Enhanced Swift-XRT position
  48. Swift GRB 230322B: Global MASTER-Net observations report
  49. GRB 230322B: Swift detection of a burst with optical counterpart
  50. GRB 230322A: Fermi GBM Final Real-time Localization
  51. GRB 230320B: GRBAlpha detection
  52. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  53. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  54. Fermi trigger No 701071944: Global MASTER-Net observations report
  55. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  56. Fermi GRB 230320A: Global MASTER-Net observations report
  57. Fermi GRB 230321A: Global MASTER-Net observations report
  58. Fermi trigger No 701058254: Global MASTER-Net observations report
  59. SGR 1806-20: Correction to GCN 33494
  60. INTEGRAL detection of a burst from SGR 1806-200
  61. GRB 230321B: AstroSat CZTI detection
  62. GRB 230320B: AstroSat CZTI detection
  63. GRB 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
  64. GRB 230321A: Fermi GBM Final Real-time Localization
  65. GRB 230320A: Fermi GBM Final Real-time Localization
  66. GRB 230314A: TURBO Optical Upper Limit
  67. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  68. Fermi trigger No 700976129: Global MASTER-Net observations report
  69. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  70. IPN triangulation of GRB 230309A
  71. Fermi GRB 230316A: Global MASTER-Net observations report
  72. GRB 230304D: AstroSat CZTI detection
  73. GRB 230316A: Fermi GBM Final Real-time Localization
  74. IPN triangulation of GRB 230304B
  75. GRB 230313A: AstroSat CZTI detection
  76. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  77. IPN triangulation of GRB 230308A (short/bright)
  78. Fermi GRB 230314A: Global MASTER-Net observations report
  79. GRB 230307A: ATCA radio detection
  80. GRB 230314A: Fermi GBM Final Real-time Localization
  81. VZLUSAT-2 detection of SGR 1806-20
  82. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  83. GRB 230307A: Swift/UVOT detection
  84. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  85. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  86. Fermi GRB 230313A: Global MASTER-Net observations report
  87. GRB 230313A: Fermi GBM Final Real-time Localization
  88. GRB 230307A: soft X-ray detection with LEIA
  89. GRB 230307A: Swift-XRT afterglow detection
  90. GRB 230309A: AstroSat CZTI detection of a bright long GRB
  91. Swift GRB230311.85: Global MASTER-Net observations report
  92. Swift GRB230311.83: Global MASTER-Net observations report
  93. Further improved IPN localization for GRB 230307A
  94. Swift GRB230311.81: Global MASTER-Net observations report
  95. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  96. Swift GRB230311.84: Global MASTER-Net observations report
  97. Swift Trigger 1159438 is also due to the Star Tracker loss of lock.
  98. Swift GRB230311.82: Global MASTER-Net observations report
  99. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  100. Alert from the HAWC Burst Monitor HAWC-230311A

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