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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 230328B NUTTelA-TAO / BSTI Early Measurements
  2. GRB 230328B: Liverpool Telescope afterglow detection
  3. GRB 230328B: OHP/T120 optical observations
  4. GRB 230328B: GIT optical follow-up
  5. GRB 230328B: OASDG optical observations
  6. GRB 230328B: Nanshan/NEXT optical upper limit
  7. GRB 230328B: Swift-XRT refined Analysis
  8. GRB 230328B: AstroSat CZTI detection
  9. GRB 230328B: Fermi GBM observation
  10. GRB 230328B: Mondy, AbAO and Kitab optical observations
  11. GRB 230328B: Enhanced Swift-XRT position
  12. GRB 230328B: Mondy optical afterglow confirmation
  13. GRB 230328B: Swift detection of a burst with an optical afterglow
  14. GRB 230328B: Fermi GBM Final Real-time Localization
  15. Fermi GRB 230328A: Global MASTER-Net observations report
  16. GRB 230328A: Fermi GBM Final Real-time Localization
  17. GRB 230325A: Swift-BAT refined analysis
  18. GRB 230325A: Swift/UVOT Upper Limits
  19. GRB 230325A: X-shooter optical afterglow and redshift
  20. GRB 230325A: Swift-XRT refined Analysis
  21. GRB 230322B: Swift-BAT refined analysis
  22. GRB 230325A: Enhanced Swift-XRT position
  23. GRB 230325A: Prompt enhanced Swift-XRT position
  24. GRB 230325A: Swift detection of a burst
  25. GRB 230320B: Fermi GBM Observation
  26. Fermi trigger No 701313046: Global MASTER-Net observations report
  27. Fermi trigger No 701321709: Global MASTER-Net observations report
  28. GRB 230322B: Swift/UVOT Detection
  29. Konus-Wind detection of GRB 230309A
  30. Konus-Wind detection of GRB 230308A
  31. Konus-Wind detection of GRB 230304B
  32. GRB 230322B: Swift-XRT refined Analysis
  33. GRB 230322B: Enhanced Swift-XRT position
  34. Swift GRB 230322B: Global MASTER-Net observations report
  35. GRB 230322B: Swift detection of a burst with optical counterpart
  36. GRB 230322A: Fermi GBM Final Real-time Localization
  37. GRB 230320B: GRBAlpha detection
  38. GRB 230321A: CALET Gamma-Ray Burst Monitor detection
  39. GRB 230320B: CALET Gamma-Ray Burst Monitor detection
  40. Fermi trigger No 701071944: Global MASTER-Net observations report
  41. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  42. Fermi GRB 230320A: Global MASTER-Net observations report
  43. Fermi GRB 230321A: Global MASTER-Net observations report
  44. Fermi trigger No 701058254: Global MASTER-Net observations report
  45. SGR 1806-20: Correction to GCN 33494
  46. INTEGRAL detection of a burst from SGR 1806-200
  47. GRB 230321B: AstroSat CZTI detection
  48. GRB 230320B: AstroSat CZTI detection
  49. GRB 230321A: BALROG localization (Fermi Trigger 701065308 / GRB 230321182)
  50. GRB 230321A: Fermi GBM Final Real-time Localization
  51. GRB 230320A: Fermi GBM Final Real-time Localization
  52. GRB 230314A: TURBO Optical Upper Limit
  53. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  54. Fermi trigger No 700976129: Global MASTER-Net observations report
  55. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  56. IPN triangulation of GRB 230309A
  57. Fermi GRB 230316A: Global MASTER-Net observations report
  58. GRB 230304D: AstroSat CZTI detection
  59. GRB 230316A: Fermi GBM Final Real-time Localization
  60. IPN triangulation of GRB 230304B
  61. GRB 230313A: AstroSat CZTI detection
  62. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  63. IPN triangulation of GRB 230308A (short/bright)
  64. Fermi GRB 230314A: Global MASTER-Net observations report
  65. GRB 230307A: ATCA radio detection
  66. GRB 230314A: Fermi GBM Final Real-time Localization
  67. VZLUSAT-2 detection of SGR 1806-20
  68. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  69. GRB 230307A: Swift/UVOT detection
  70. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  71. GRB 230313A: BALROG localization (Fermi Trigger 700400328 / GRB 230313485)
  72. Fermi GRB 230313A: Global MASTER-Net observations report
  73. GRB 230313A: Fermi GBM Final Real-time Localization
  74. GRB 230307A: soft X-ray detection with LEIA
  75. GRB 230307A: Swift-XRT afterglow detection
  76. GRB 230309A: AstroSat CZTI detection of a bright long GRB
  77. Swift GRB230311.85: Global MASTER-Net observations report
  78. Swift GRB230311.83: Global MASTER-Net observations report
  79. Further improved IPN localization for GRB 230307A
  80. Swift GRB230311.81: Global MASTER-Net observations report
  81. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  82. Swift GRB230311.84: Global MASTER-Net observations report
  83. Swift Trigger 1159438 is also due to the Star Tracker loss of lock.
  84. Swift GRB230311.82: Global MASTER-Net observations report
  85. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  86. Alert from the HAWC Burst Monitor HAWC-230311A
  87. TESS Detection of the Optical Afterglow of GRB230307A
  88. GRB 230308A: CALET Gamma-Ray Burst Monitor detection
  89. Trigger 1159327: Swift detection of SGR1806-20
  90. GRB 230310A: AstroSat CZTI detection
  91. GRB 230307A: GECKO optical observations and detections of the afterglow
  92. GRB 230307A: MAXI/GSC upper limit
  93. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  94. Fermi GRB 230310A: Global MASTER-Net observations report
  95. GRB 230310A: Fermi GBM Final Real-time Localization
  96. GRB 230307A: AGILE/MCAL analysis
  97. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  98. GRB 230307A: Erratum of the GCN 33441
  99. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  100. GRB 230308A: Fermi GBM detection

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