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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 trigger No 701321709: Global MASTER-Net observations report
  2. GRB 230322B: Swift/UVOT Detection
  3. Konus-Wind detection of GRB 230309A
  4. Konus-Wind detection of GRB 230308A
  5. Konus-Wind detection of GRB 230304B
  6. GRB 230322B: Swift-XRT refined Analysis
  7. GRB 230322B: Enhanced Swift-XRT position
  8. Swift GRB 230322B: Global MASTER-Net observations report
  9. GRB 230322B: Swift detection of a burst with optical counterpart
  10. GRB 230322A: Fermi GBM Final Real-time Localization
  11. GRB 230320B: GRBAlpha detection
  12. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  13. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  14. Fermi trigger No 701071944: Global MASTER-Net observations report
  15. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  16. Fermi GRB 230320A: Global MASTER-Net observations report
  17. Fermi GRB 230321A: Global MASTER-Net observations report
  18. Fermi trigger No 701058254: Global MASTER-Net observations report
  19. SGR 1806-20: Correction to GCN 33494
  20. INTEGRAL detection of a burst from SGR 1806-200
  21. GRB 230321B: AstroSat CZTI detection
  22. GRB 230320B: AstroSat CZTI detection
  23. GRB 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
  24. GRB 230321A: Fermi GBM Final Real-time Localization
  25. GRB 230320A: Fermi GBM Final Real-time Localization
  26. GRB 230314A: TURBO Optical Upper Limit
  27. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  28. Fermi trigger No 700976129: Global MASTER-Net observations report
  29. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  30. IPN triangulation of GRB 230309A
  31. Fermi GRB 230316A: Global MASTER-Net observations report
  32. GRB 230304D: AstroSat CZTI detection
  33. GRB 230316A: Fermi GBM Final Real-time Localization
  34. IPN triangulation of GRB 230304B
  35. GRB 230313A: AstroSat CZTI detection
  36. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  37. IPN triangulation of GRB 230308A (short/bright)
  38. Fermi GRB 230314A: Global MASTER-Net observations report
  39. GRB 230307A: ATCA radio detection
  40. GRB 230314A: Fermi GBM Final Real-time Localization
  41. VZLUSAT-2 detection of SGR 1806-20
  42. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  43. GRB 230307A: Swift/UVOT detection
  44. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  45. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  46. Fermi GRB 230313A: Global MASTER-Net observations report
  47. GRB 230313A: Fermi GBM Final Real-time Localization
  48. GRB 230307A: soft X-ray detection with LEIA
  49. GRB 230307A: Swift-XRT afterglow detection
  50. GRB 230309A: AstroSat CZTI detection of a bright long GRB
  51. Swift GRB230311.85: Global MASTER-Net observations report
  52. Swift GRB230311.83: Global MASTER-Net observations report
  53. Further improved IPN localization for GRB 230307A
  54. Swift GRB230311.81: Global MASTER-Net observations report
  55. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  56. Swift GRB230311.84: Global MASTER-Net observations report
  57. Swift Trigger 1159438 is also due to the Star Tracker loss of lock.
  58. Swift GRB230311.82: Global MASTER-Net observations report
  59. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  60. Alert from the HAWC Burst Monitor HAWC-230311A
  61. TESS Detection of the Optical Afterglow of GRB230307A
  62. GRB 230308A: CALET Gamma-Ray Burst Monitor detection
  63. Trigger 1159327: Swift detection of SGR1806-20
  64. GRB 230310A: AstroSat CZTI detection
  65. GRB 230307A: GECKO optical observations and detections of the afterglow
  66. GRB 230307A: MAXI/GSC upper limit
  67. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  68. Fermi GRB 230310A: Global MASTER-Net observations report
  69. GRB 230310A: Fermi GBM Final Real-time Localization
  70. GRB 230307A: AGILE/MCAL analysis
  71. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  72. GRB 230307A: Erratum of the GCN 33441
  73. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  74. GRB 230308A: Fermi GBM detection
  75. GRB 230307A: Possible optical afterglow
  76. GRB 230307A: ASO-S/HXI detection
  77. GRB 230307A: AstroSat LAXPC detection
  78. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  79. GRB 230308A: AGILE/MCAL detection
  80. GRB 230307A: optical upper limit
  81. GRB 230217A: ATCA rapid-response radio detection
  82. Swift Trigger 1159108 is not a GRB
  83. GRB 230307A: Swift/BAT upper limits on the early afterglow
  84. GRB 230307A: Upper limits from a neutrino search with IceCube
  85. GRB 230307A: Swift-XRT observations
  86. Fermi GRB 230307A: Global MASTER-Net observations report
  87. Konus-Wind detection of GRB 230307A
  88. GRB 230228A: VIRT Optical Upper Limit
  89. Improved IPN localization for GRB 230307A
  90. GRB 230307A: VZLUSAT-2 detection
  91. GRB 230304B: CALET Gamma-Ray Burst Monitor detection
  92. Fermi GRB 230308A: Global MASTER-Net observations report
  93. GRB 230308A: BALROG localization (Fermi Trigger 699975152 / GRB 230308564)
  94. GRB 230308A: Fermi GBM Final Real-time Localization
  95. GRB 230307A: Tiled Swift observations
  96. GRB 230307A: Detection by GRBAlpha
  97. GRB 230305A: Detection by GRBAlpha
  98. GRB 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656)
  99. GRB 230307A: AstroSat CZTI detection
  100. GRB 230307A: possibly the second highest GRB energy fluence ever identified

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