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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 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
  2. GRB 230321A: Fermi GBM Final Real-time Localization
  3. GRB 230320A: Fermi GBM Final Real-time Localization
  4. GRB 230314A: TURBO Optical Upper Limit
  5. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  6. Fermi trigger No 700976129: Global MASTER-Net observations report
  7. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  8. IPN triangulation of GRB 230309A
  9. Fermi GRB 230316A: Global MASTER-Net observations report
  10. GRB 230304D: AstroSat CZTI detection
  11. GRB 230316A: Fermi GBM Final Real-time Localization
  12. IPN triangulation of GRB 230304B
  13. GRB 230313A: AstroSat CZTI detection
  14. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  15. IPN triangulation of GRB 230308A (short/bright)
  16. Fermi GRB 230314A: Global MASTER-Net observations report
  17. GRB 230307A: ATCA radio detection
  18. GRB 230314A: Fermi GBM Final Real-time Localization
  19. VZLUSAT-2 detection of SGR 1806-20
  20. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  21. GRB 230307A: Swift/UVOT detection
  22. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  23. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  24. Fermi GRB 230313A: Global MASTER-Net observations report
  25. GRB 230313A: Fermi GBM Final Real-time Localization
  26. GRB 230307A: soft X-ray detection with LEIA
  27. GRB 230307A: Swift-XRT afterglow detection
  28. GRB 230309A: AstroSat CZTI detection of a bright long GRB
  29. Swift GRB230311.85: Global MASTER-Net observations report
  30. Swift GRB230311.83: Global MASTER-Net observations report
  31. Further improved IPN localization for GRB 230307A
  32. Swift GRB230311.81: Global MASTER-Net observations report
  33. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  34. Swift GRB230311.84: Global MASTER-Net observations report
  35. Swift Trigger 1159438 is also due to the Star Tracker loss of lock.
  36. Swift GRB230311.82: Global MASTER-Net observations report
  37. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  38. Alert from the HAWC Burst Monitor HAWC-230311A
  39. TESS Detection of the Optical Afterglow of GRB230307A
  40. GRB 230308A: CALET Gamma-Ray Burst Monitor detection
  41. Trigger 1159327: Swift detection of SGR1806-20
  42. GRB 230310A: AstroSat CZTI detection
  43. GRB 230307A: GECKO optical observations and detections of the afterglow
  44. GRB 230307A: MAXI/GSC upper limit
  45. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  46. Fermi GRB 230310A: Global MASTER-Net observations report
  47. GRB 230310A: Fermi GBM Final Real-time Localization
  48. GRB 230307A: AGILE/MCAL analysis
  49. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  50. GRB 230307A: Erratum of the GCN 33441
  51. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  52. GRB 230308A: Fermi GBM detection
  53. GRB 230307A: Possible optical afterglow
  54. GRB 230307A: ASO-S/HXI detection
  55. GRB 230307A: AstroSat LAXPC detection
  56. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  57. GRB 230308A: AGILE/MCAL detection
  58. GRB 230307A: optical upper limit
  59. GRB 230217A: ATCA rapid-response radio detection
  60. Swift Trigger 1159108 is not a GRB
  61. GRB 230307A: Swift/BAT upper limits on the early afterglow
  62. GRB 230307A: Upper limits from a neutrino search with IceCube
  63. GRB 230307A: Swift-XRT observations
  64. Fermi GRB 230307A: Global MASTER-Net observations report
  65. Konus-Wind detection of GRB 230307A
  66. GRB 230228A: VIRT Optical Upper Limit
  67. Improved IPN localization for GRB 230307A
  68. GRB 230307A: VZLUSAT-2 detection
  69. GRB 230304B: CALET Gamma-Ray Burst Monitor detection
  70. Fermi GRB 230308A: Global MASTER-Net observations report
  71. GRB 230308A: BALROG localization (Fermi Trigger 699975152 / GRB 230308564)
  72. GRB 230308A: Fermi GBM Final Real-time Localization
  73. GRB 230307A: Tiled Swift observations
  74. GRB 230307A: Detection by GRBAlpha
  75. GRB 230305A: Detection by GRBAlpha
  76. GRB 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656)
  77. GRB 230307A: AstroSat CZTI detection
  78. GRB 230307A: possibly the second highest GRB energy fluence ever identified
  79. IPN triangulation of GRB 230307A (long/very bright)
  80. GRB 230307A: AGILE/MCAL detection
  81. GRB 230307A: Fermi GBM Observation of a very bright burst
  82. Solar Orbiter STIX observation of GRB 230307A
  83. IceCube-230306A: Upper limits from a search for additional neutrino events in IceCube
  84. Fermi-LAT gamma-ray observations of IceCube-230306A
  85. GRB 230307A: Fermi GBM detection of a very bright GRB
  86. GRB 230307A: GECAM detection of an extremely bright burst
  87. GRB 230307A: Fermi GBM Final Real-time Localization
  88. Fermi trigger No 699811746: Global MASTER-Net observations report
  89. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  90. IceCube Alert 230306.46: Global MASTER-Net observations report
  91. GRB 230304C: AstroSat CZTI detection
  92. GRB 230304B: AstroSat CZTI detection
  93. GRB 230304A: AstroSat CZTI detection
  94. GRB 230304B: Detection by GRBAlpha
  95. GRB 230304C: Fermi GBM Final Real-time Localization
  96. GRB 230304B: Fermi GBM Final Real-time Localization
  97. GRB 230304A: Fermi GBM Final Real-time Localization
  98. GRB 230228A: 6 GHz VLA radio upper limit
  99. GRB 230228A: Swift-BAT refined analysis
  100. GRB 230228A: Swift/UVOT Upper Limits

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