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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. Konus-Wind detection of GRB 230304B
  2. GRB 230322B: Swift-XRT refined Analysis
  3. GRB 230322B: Enhanced Swift-XRT position
  4. Swift GRB 230322B: Global MASTER-Net observations report
  5. GRB 230322B: Swift detection of a burst with optical counterpart
  6. GRB 230322A: Fermi GBM Final Real-time Localization
  7. GRB 230320B: GRBAlpha detection
  8. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  9. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  10. Fermi trigger No 701071944: Global MASTER-Net observations report
  11. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  12. Fermi GRB 230320A: Global MASTER-Net observations report
  13. Fermi GRB 230321A: Global MASTER-Net observations report
  14. Fermi trigger No 701058254: Global MASTER-Net observations report
  15. SGR 1806-20: Correction to GCN 33494
  16. INTEGRAL detection of a burst from SGR 1806-200
  17. GRB 230321B: AstroSat CZTI detection
  18. GRB 230320B: AstroSat CZTI detection
  19. GRB 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
  20. GRB 230321A: Fermi GBM Final Real-time Localization
  21. GRB 230320A: Fermi GBM Final Real-time Localization
  22. GRB 230314A: TURBO Optical Upper Limit
  23. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  24. Fermi trigger No 700976129: Global MASTER-Net observations report
  25. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  26. IPN triangulation of GRB 230309A
  27. Fermi GRB 230316A: Global MASTER-Net observations report
  28. GRB 230304D: AstroSat CZTI detection
  29. GRB 230316A: Fermi GBM Final Real-time Localization
  30. IPN triangulation of GRB 230304B
  31. GRB 230313A: AstroSat CZTI detection
  32. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  33. IPN triangulation of GRB 230308A (short/bright)
  34. Fermi GRB 230314A: Global MASTER-Net observations report
  35. GRB 230307A: ATCA radio detection
  36. GRB 230314A: Fermi GBM Final Real-time Localization
  37. VZLUSAT-2 detection of SGR 1806-20
  38. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  39. GRB 230307A: Swift/UVOT detection
  40. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  41. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  42. Fermi GRB 230313A: Global MASTER-Net observations report
  43. GRB 230313A: Fermi GBM Final Real-time Localization
  44. GRB 230307A: soft X-ray detection with LEIA
  45. GRB 230307A: Swift-XRT afterglow detection
  46. GRB 230309A: AstroSat CZTI detection of a bright long GRB
  47. Swift GRB230311.85: Global MASTER-Net observations report
  48. Swift GRB230311.83: Global MASTER-Net observations report
  49. Further improved IPN localization for GRB 230307A
  50. Swift GRB230311.81: Global MASTER-Net observations report
  51. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  52. Swift GRB230311.84: Global MASTER-Net observations report
  53. Swift Trigger 1159438 is also due to the Star Tracker loss of lock.
  54. Swift GRB230311.82: Global MASTER-Net observations report
  55. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  56. Alert from the HAWC Burst Monitor HAWC-230311A
  57. TESS Detection of the Optical Afterglow of GRB230307A
  58. GRB 230308A: CALET Gamma-Ray Burst Monitor detection
  59. Trigger 1159327: Swift detection of SGR1806-20
  60. GRB 230310A: AstroSat CZTI detection
  61. GRB 230307A: GECKO optical observations and detections of the afterglow
  62. GRB 230307A: MAXI/GSC upper limit
  63. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  64. Fermi GRB 230310A: Global MASTER-Net observations report
  65. GRB 230310A: Fermi GBM Final Real-time Localization
  66. GRB 230307A: AGILE/MCAL analysis
  67. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  68. GRB 230307A: Erratum of the GCN 33441
  69. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  70. GRB 230308A: Fermi GBM detection
  71. GRB 230307A: Possible optical afterglow
  72. GRB 230307A: ASO-S/HXI detection
  73. GRB 230307A: AstroSat LAXPC detection
  74. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  75. GRB 230308A: AGILE/MCAL detection
  76. GRB 230307A: optical upper limit
  77. GRB 230217A: ATCA rapid-response radio detection
  78. Swift Trigger 1159108 is not a GRB
  79. GRB 230307A: Swift/BAT upper limits on the early afterglow
  80. GRB 230307A: Upper limits from a neutrino search with IceCube
  81. GRB 230307A: Swift-XRT observations
  82. Fermi GRB 230307A: Global MASTER-Net observations report
  83. Konus-Wind detection of GRB 230307A
  84. GRB 230228A: VIRT Optical Upper Limit
  85. Improved IPN localization for GRB 230307A
  86. GRB 230307A: VZLUSAT-2 detection
  87. GRB 230304B: CALET Gamma-Ray Burst Monitor detection
  88. Fermi GRB 230308A: Global MASTER-Net observations report
  89. GRB 230308A: BALROG localization (Fermi Trigger 699975152 / GRB 230308564)
  90. GRB 230308A: Fermi GBM Final Real-time Localization
  91. GRB 230307A: Tiled Swift observations
  92. GRB 230307A: Detection by GRBAlpha
  93. GRB 230305A: Detection by GRBAlpha
  94. GRB 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656)
  95. GRB 230307A: AstroSat CZTI detection
  96. GRB 230307A: possibly the second highest GRB energy fluence ever identified
  97. IPN triangulation of GRB 230307A (long/very bright)
  98. GRB 230307A: AGILE/MCAL detection
  99. GRB 230307A: Fermi GBM Observation of a very bright burst
  100. Solar Orbiter STIX observation of GRB 230307A

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