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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"

22062 results found.

  1. GRB 230427A: GIT optical upper limit
  2. GRB 230427A: Bassano Bresciano Observatory upper limit
  3. Swift GRB230427.44: Global MASTER-Net observations report
  4. GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
  5. Fermi trigger No 704233744: Global MASTER-Net observations report
  6. GRB 230423A: Swift/UVOT Upper Limits
  7. GRB 230420A: Lowell Discovery Telescope Optical Detection
  8. GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
  9. GRB 230420A: Swift/UVOT Upper Limits
  10. GRB 230421: Swift/BAT-GUANO arcminute localization
  11. GRB 230420A: NOT optical afterglow confirmation
  12. GRB 230420A: Gaoyazi/GOT optical upper limit
  13. GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
  14. Fermi-LAT gamma-ray observations of IceCube-230416A
  15. GRB 230414B: Nickel and KAIT telescope optical observations
  16. GRB 230414B: Swift/UVOT Detection
  17. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  18. GRB 230415A: Swift/BAT-GUANO detection
  19. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  20. GRB 230307A: iTelescope optical upper limit (likely)
  21. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  22. Fermi trigger No 703284533: Global MASTER-Net observations report
  23. GRB 230414B: Lulin 40cm-SLT optical limit
  24. GRB 230414B: Bassano Bresciano Observatory optical observations
  25. GRB 230414B: Redshift from OSIRIS/GTC
  26. GRB 230414B: AbAO optical observations
  27. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  28. GRB 230414B: Dabancheng/GHOST optical observations
  29. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  30. GRB 230414B: SAO RAS optical observations
  31. GRB 230414B: 1.3m DFOT Optical observations
  32. Fermi GRB 230414A: Global MASTER-Net observations report
  33. GRB 230414B: Nanshan/HMT optical afterglow detection
  34. Swift GRB 230414B: Global MASTER-Net observations report
  35. Fermi GRB 230409C: Global MASTER-Net observations report
  36. Fermi GRB 230409A: Global MASTER-Net observations report
  37. Fermi trigger No 702745263: Global MASTER-Net observations report
  38. Swift GRB 230409B: Global MASTER-Net observations report
  39. GRB 230409B: Swift/UVOT Detection
  40. MAXI GRB230408.82: Global MASTER-Net observations report
  41. Fermi-LAT gamma-ray observations of IceCube-230405A
  42. GRB 230405B: MeerLICHT upper limits
  43. IceCube Alert 230405.56: Global MASTER-Net observations report
  44. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  45. GRB 230307A: good match with kilonova models
  46. GRB 230405B: Swift/UVOT Upper Limits
  47. Swift GRB 230405B: Global MASTER-Net observations report
  48. GRB 230307A: JWST observations consistent with the presence of a kilonova
  49. Fermi GRB 230405A: Global MASTER-Net observations report
  50. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  51. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  52. GRB 230328B: Swift/UVOT Detection
  53. Fermi GRB 230402A: Global MASTER-Net observations report
  54. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  55. GRB 230328B: CAHA 2.2m/CAFOS detection
  56. GRB 230328B: 3.6m DOT multiband optical observation
  57. Fermi trigger No 701883729: Global MASTER-Net observations report
  58. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  59. GRB 230328B: Liverpool Telescope afterglow detection
  60. GRB 230328B: OHP/T120 optical observations
  61. GRB 230328B: GIT optical follow-up
  62. GRB 230328B: OASDG optical observations
  63. GRB 230328B: Nanshan/NEXT optical upper limit
  64. GRB 230328B: Mondy, AbAO and Kitab optical observations
  65. Fermi GRB 230328A: Global MASTER-Net observations report
  66. GRB 230325A: Swift/UVOT Upper Limits
  67. Fermi trigger No 701313046: Global MASTER-Net observations report
  68. Fermi trigger No 701321709: Global MASTER-Net observations report
  69. GRB 230322B: Swift/UVOT Detection
  70. Konus-Wind detection of GRB 230309A
  71. Konus-Wind detection of GRB 230304B
  72. Swift GRB 230322B: Global MASTER-Net observations report
  73. Fermi trigger No 701071944: Global MASTER-Net observations report
  74. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  75. Fermi GRB 230320A: Global MASTER-Net observations report
  76. Fermi GRB 230321A: Global MASTER-Net observations report
  77. Fermi trigger No 701058254: Global MASTER-Net observations report
  78. Fermi trigger No 700976129: Global MASTER-Net observations report
  79. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  80. Fermi GRB 230316A: Global MASTER-Net observations report
  81. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  82. Fermi GRB 230314A: Global MASTER-Net observations report
  83. GRB 230307A: ATCA radio detection
  84. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  85. GRB 230307A: Swift/UVOT detection
  86. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  87. Fermi GRB 230313A: Global MASTER-Net observations report
  88. GRB 230307A: soft X-ray detection with LEIA
  89. GRB 230307A: Swift-XRT afterglow detection
  90. Swift GRB230311.85: Global MASTER-Net observations report
  91. Swift GRB230311.83: Global MASTER-Net observations report
  92. Swift GRB230311.81: Global MASTER-Net observations report
  93. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  94. Swift GRB230311.84: Global MASTER-Net observations report
  95. Swift GRB230311.82: Global MASTER-Net observations report
  96. Triggers 1159434, 1159435 and 1159437: Swift detection of Sco X-1 due to Star Tracker loss of lock
  97. Alert from the HAWC Burst Monitor HAWC-230311A
  98. TESS Detection of the Optical Afterglow of GRB230307A
  99. Trigger 1159327: Swift detection of SGR1806-20
  100. GRB 230307A: GECKO optical observations and detections of the afterglow

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