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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"

22051 results found.

  1. GRB 230420A: Gaoyazi/GOT optical upper limit
  2. GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
  3. Fermi-LAT gamma-ray observations of IceCube-230416A
  4. GRB 230414B: Nickel and KAIT telescope optical observations
  5. GRB 230414B: Swift/UVOT Detection
  6. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  7. GRB 230415A: Swift/BAT-GUANO detection
  8. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  9. GRB 230307A: iTelescope optical upper limit (likely)
  10. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  11. Fermi trigger No 703284533: Global MASTER-Net observations report
  12. GRB 230414B: Lulin 40cm-SLT optical limit
  13. GRB 230414B: Bassano Bresciano Observatory optical observations
  14. GRB 230414B: Redshift from OSIRIS/GTC
  15. GRB 230414B: AbAO optical observations
  16. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  17. GRB 230414B: Dabancheng/GHOST optical observations
  18. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  19. GRB 230414B: SAO RAS optical observations
  20. GRB 230414B: 1.3m DFOT Optical observations
  21. Fermi GRB 230414A: Global MASTER-Net observations report
  22. GRB 230414B: Nanshan/HMT optical afterglow detection
  23. Swift GRB 230414B: Global MASTER-Net observations report
  24. Fermi GRB 230409C: Global MASTER-Net observations report
  25. Fermi GRB 230409A: Global MASTER-Net observations report
  26. Fermi trigger No 702745263: Global MASTER-Net observations report
  27. Swift GRB 230409B: Global MASTER-Net observations report
  28. GRB 230409B: Swift/UVOT Detection
  29. MAXI GRB230408.82: Global MASTER-Net observations report
  30. Fermi-LAT gamma-ray observations of IceCube-230405A
  31. GRB 230405B: MeerLICHT upper limits
  32. IceCube Alert 230405.56: Global MASTER-Net observations report
  33. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  34. GRB 230307A: good match with kilonova models
  35. GRB 230405B: Swift/UVOT Upper Limits
  36. Swift GRB 230405B: Global MASTER-Net observations report
  37. GRB 230307A: JWST observations consistent with the presence of a kilonova
  38. Fermi GRB 230405A: Global MASTER-Net observations report
  39. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  40. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  41. GRB 230328B: Swift/UVOT Detection
  42. Fermi GRB 230402A: Global MASTER-Net observations report
  43. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  44. GRB 230328B: CAHA 2.2m/CAFOS detection
  45. GRB 230328B: 3.6m DOT multiband optical observation
  46. Fermi trigger No 701883729: Global MASTER-Net observations report
  47. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  48. GRB 230328B: Liverpool Telescope afterglow detection
  49. GRB 230328B: OHP/T120 optical observations
  50. GRB 230328B: GIT optical follow-up
  51. GRB 230328B: OASDG optical observations
  52. GRB 230328B: Nanshan/NEXT optical upper limit
  53. GRB 230328B: Mondy, AbAO and Kitab optical observations
  54. Fermi GRB 230328A: Global MASTER-Net observations report
  55. GRB 230325A: Swift/UVOT Upper Limits
  56. Fermi trigger No 701313046: Global MASTER-Net observations report
  57. Fermi trigger No 701321709: Global MASTER-Net observations report
  58. GRB 230322B: Swift/UVOT Detection
  59. Konus-Wind detection of GRB 230309A
  60. Konus-Wind detection of GRB 230304B
  61. Swift GRB 230322B: Global MASTER-Net observations report
  62. Fermi trigger No 701071944: Global MASTER-Net observations report
  63. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  64. Fermi GRB 230320A: Global MASTER-Net observations report
  65. Fermi GRB 230321A: Global MASTER-Net observations report
  66. Fermi trigger No 701058254: Global MASTER-Net observations report
  67. Fermi trigger No 700976129: Global MASTER-Net observations report
  68. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  69. Fermi GRB 230316A: Global MASTER-Net observations report
  70. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  71. Fermi GRB 230314A: Global MASTER-Net observations report
  72. GRB 230307A: ATCA radio detection
  73. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  74. GRB 230307A: Swift/UVOT detection
  75. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  76. Fermi GRB 230313A: Global MASTER-Net observations report
  77. GRB 230307A: soft X-ray detection with LEIA
  78. GRB 230307A: Swift-XRT afterglow detection
  79. Swift GRB230311.85: Global MASTER-Net observations report
  80. Swift GRB230311.83: Global MASTER-Net observations report
  81. Swift GRB230311.81: Global MASTER-Net observations report
  82. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  83. Swift GRB230311.84: Global MASTER-Net observations report
  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. Trigger 1159327: Swift detection of SGR1806-20
  89. GRB 230307A: GECKO optical observations and detections of the afterglow
  90. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  91. Fermi GRB 230310A: Global MASTER-Net observations report
  92. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  93. GRB 230307A: Erratum of the GCN 33441
  94. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  95. GRB 230307A: Possible optical afterglow
  96. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  97. GRB 230217A: ATCA rapid-response radio detection
  98. GRB 230307A: Swift/BAT upper limits on the early afterglow
  99. GRB 230307A: Swift-XRT observations
  100. Fermi GRB 230307A: Global MASTER-Net observations report

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