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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"

19128 results found.

  1. GRB 251007B: SVOM detection of a faint burst
  2. GRB 251007B: Swift detection of a burst
  3. GRB 251007A: Swift detection of a burst with an optical counterpart
  4. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  5. GRB 251005C: SVOM/GRM observation of a likely short GRB
  6. GRB 251005C: COLIBRÍ optical observations
  7. GRB 251003A: LAST optical observations
  8. GRB 251005C: SVOM/VT optical candidate
  9. GRB 251005C: AstroSat CZTI detection
  10. GRB 251005​C: Swift/UVOT Upper Limits
  11. GRB 251005C: Swift-XRT refined Analysis
  12. GRB 251005C: Fermi GBM Observation
  13. Swift GRB 251005A: Global MASTER-Net observations report
  14. GRB 251005C: Enhanced Swift-XRT position
  15. GRB 251005C: GOTO optical upper limits
  16. GRB 251005C: Swift detection of a burst
  17. GRB 251003A: Swift-BAT refined analysis
  18. GRB 251003A: Swift/UVOT Upper Limits
  19. GRB 251002A: Swift/UVOT detection
  20. GRB 251003A: Swift-XRT refined Analysis
  21. GRB 251003A: COLIBRÍ photometric redshift
  22. GRB 251003A: Enhanced Swift-XRT position
  23. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  24. GRB 251003A: Kilonova-Catcher optical afterglow detection
  25. GRB 251002A: Swift-XRT afterglow detection
  26. GRB 251001B: AbAO optical upper limit
  27. GRB 251003A: LCOGT Optical Detection
  28. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  29. GRB 251003A: 1.5m OSN afterglow candidate
  30. GRB 251003A: Prompt enhanced Swift-XRT position
  31. GRB 251003A: Swift detection of a burst
  32. Swift GRB251003A: Global MASTER-Net observations report
  33. GRB 251001B: Swift-BAT refined analysis
  34. GRB 251001B: Swift/UVOT Detection
  35. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  36. GRB 251001B: Swift-XRT refined Analysis
  37. GRB 251001B: SVOM/VT optical observation
  38. Swift GRB 251001B: Global MASTER-Net observations report
  39. GRB 251001B: Fermi GBM Observation
  40. GRB 251001B: Enhanced Swift-XRT position
  41. GRB 251001B: LCOGT Optical Observations
  42. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  43. GRB 251001B: GOTO optical counterpart detection
  44. GRB 251001B: Swift detection of a burst
  45. GRB 250925A: MAO/AZT-22 optical observations
  46. GRB 250925A: Mondy I-band optical observations
  47. GRB 250924A: SVOM/GRM observation
  48. GRB 250925A: Swift-XRT refined Analysis
  49. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  50. GRB 250925A: Swift/UVOT Upper Limits
  51. GRB 250925A: Swift-BAT refined analysis
  52. GRB 250925A: Mondy and AbAO optical observations
  53. GRB 250925A: COLIBRÍ photometric redshift
  54. GRB 250925A : MITSuME Akeno optical upper limits
  55. GRB 250925A: JinShan optical observations
  56. GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+
  57. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  58. GRB 250925A: COLIBRÍ optical photometry of the afterglow
  59. GRB250925A: Liverpool Telescope optical observations
  60. GRB 250925A: Leavitt Observatory optical upper limit
  61. GRB 250925A: Enhanced Swift-XRT position
  62. GRB 250924A: Swift-BAT refined analysis
  63. GRB 250925A: GROWTH-India Telescope Upper Limits
  64. GRB 250925A: Swift detection of a burst
  65. Swift GRB 250925A: Global MASTER-Net observations report
  66. GRB 250924A: 1.6m Mephisto optical upper limits
  67. GRB 250924A: NOT optical observations
  68. GRB 250924A: AstroSat CZTI detection
  69. GRB 250920B: AstroSat CZTI detection
  70. GRB 250924A: SVOM/VT optical observation
  71. GRB 250924A: Swift/UVOT Detection
  72. GRB 250924A: Swift-XRT refined Analysis
  73. GRB 250924A: Enhanced Swift-XRT position
  74. GRB 250924A: GROWTH-India Telescope Upper Limits
  75. GRB 250924A: KAIT optical observations
  76. GRB 250924A: Mondy optical observations, afterglow fading
  77. GRB 250924A: Kilonova-Catcher optical afterglow detection
  78. GRB 250920C: Kilonova-Catcher optical afterglow detection
  79. GRB 250920C: TRT optical observation
  80. GRB 250924A: COLIBRÍ optical observations
  81. Swift GRB 250924A: Global MASTER-Net observations report
  82. GRB 250924A: DDOTI Detection of the Optical Counterpart
  83. GRB 250924A: Swift detection of a burst with an optical counterpart
  84. GRB 250920B: AbAO optical upper limits
  85. Konus-Wind detection of GRB 250920C
  86. GRB 250920B: CrAO ZTSH optical observations
  87. GRB 250920C: COLIBRÍ optical observations
  88. GRB 250920C: PRIME near-infrared detection
  89. Konus-Wind detection of GRB 250920B
  90. Konus-Wind detection of GRB 250911A
  91. GRB 250916A: Swift/UVOT Detection
  92. GRB 250920B: Glowbug gamma-ray detection
  93. GRB 250920C: Swift-XRT refined Analysis
  94. GRB 250920B: Kitab-ISON optical upper limit
  95. GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
  96. GRB 250920C: SVOM/GRM observation
  97. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  98. GRB 250917B: KAIT optical upper limit
  99. GRB 250920C: GROWTH-India Telescope optical observations
  100. GRB 250920C: Swift-BAT refined analysis

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