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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

26119 results found.

  1. GRB 250924A: SVOM/VT optical observation
  2. GRB 250924A: Swift/UVOT Detection
  3. GRB 250924A: Swift-XRT refined Analysis
  4. GRB 250924A: Enhanced Swift-XRT position
  5. GRB 250924A: GROWTH-India Telescope Upper Limits
  6. GRB 250924A: KAIT optical observations
  7. GRB 250924A: Mondy optical observations, afterglow fading
  8. GRB 250924A: Kilonova-Catcher optical afterglow detection
  9. GRB 250920C: Kilonova-Catcher optical afterglow detection
  10. GRB 250920C: TRT optical observation
  11. GRB 250924A: COLIBRÍ optical observations
  12. Swift GRB 250924A: Global MASTER-Net observations report
  13. GRB 250919A / EP250919a: further LCO optical observation
  14. GRB 250924A: DDOTI Detection of the Optical Counterpart
  15. GRB 250924A: Swift detection of a burst with an optical counterpart
  16. GRB 250920B: AbAO optical upper limits
  17. Konus-Wind detection of GRB 250920C
  18. GRB 250920C: KAIT optical observations
  19. GRB 250920C: VLT redshift confirmation z = 1.399
  20. GRB 250920B: CrAO ZTSH optical observations
  21. GRB 250920C: SALT redshift confirmation
  22. GRB 250920C: COLIBRÍ optical observations
  23. GRB 250920C: PRIME near-infrared detection
  24. Konus-Wind detection of GRB 250920B
  25. Konus-Wind detection of GRB 250911A
  26. GRB 250916A: Swift/UVOT Detection
  27. GRB 250920B: Glowbug gamma-ray detection
  28. GRB 250920C: Swift-XRT refined Analysis
  29. GRB 250920B: Kitab-ISON optical upper limit
  30. GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
  31. GRB 250920C: SVOM/GRM observation
  32. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  33. GRB 250917B: KAIT optical upper limit
  34. GRB 250920C: GROWTH-India Telescope optical observations
  35. GRB 250920C: Swift-BAT refined analysis
  36. GRB 250920B: Swift-BAT refined analysis
  37. GRB 250920C: Enhanced Swift-XRT position
  38. GRB 250920C: Swift/UVOT Detection
  39. GRB 250920B: Fermi GBM Observation
  40. GRB 250920C: Fermi GBM Observation
  41. Swift GRB 250920C: Global MASTER-Net observations report
  42. GRB 250920B: Swift/UVOT Detection
  43. GRB 250920C: Optical counterpart detection by LCO
  44. GRB250920C: LCOGT Optical Detection
  45. GRB 250920B: Enhanced Swift-XRT position
  46. GRB 250920B: Swift-XRT refined Analysis
  47. GRB 250920B: SVOM/C-GFT optical observations
  48. GRB 250920C: GOTO optical counterpart candidate
  49. GRB 250920C: Swift detection of a burst
  50. Swift GRB 250920B: Global MASTER-Net observations report
  51. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  52. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  53. GRB 250916A: Mondy R-band optical observations
  54. GRB 250919A: Fermi GBM Observation
  55. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  56. GRB 250919A: Swift-XRT afterglow detection
  57. GRB 250916A: KAIT optical observations
  58. GRB 250917B: Swift-BAT refined analysis
  59. GRB 250917B: Swift/UVOT Upper Limits
  60. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  61. GRB 250916A: Swift-XRT observations
  62. GRB250917B: WFST optical observations
  63. GRB 250916A: Swift ToO observations
  64. GRB 250917B: Fermi GBM Observation
  65. GRB 250917B: Swift-XRT observations
  66. GRB 250917B: Swift detection of a short burst
  67. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  68. GRB 250912A: Swift-XRT observations
  69. GRB 250912A: VLT observations
  70. GRB 250911A: Insight-HXMT detection
  71. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  72. GRB 250911A: GECAM-B detection
  73. GRB 250911A: Swift-BAT refined analysis
  74. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  75. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  76. EP250911a: SVOM/VT optical observation
  77. GRB 250911A: MASTER optical counterpart observations
  78. GRB 250911A: Swift-XRT refined Analysis
  79. EP250911a: Swift-XRT observations
  80. GRB 250911A: Swift/UVOT Detection
  81. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  82. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  83. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  84. GRB 250911A: Enhanced Swift-XRT position
  85. GRB 250911A: Swift-XRT observations
  86. GRB 250911A: COLIBRÍ optical counterpart candidate
  87. GRB 250911A: Swift detection of a burst
  88. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  89. GRB 250910A: SVOM/MXT possible afterglow detection
  90. GRB 250702B: Late time Chandra observations
  91. EP250908b/EP#01709240653: Swift/UVOT Detection
  92. EP#01709240653: Swift-XRT observations
  93. EP250908c: VLT/FORS2 optical counterpart identification
  94. GRB 250905A: Swift-BAT refined analysis
  95. GRB 250903A: Swift-XRT afterglow detection
  96. GRB 250905A: Swift-XRT refined Analysis
  97. GRB 250904A: Swift-BAT refined analysis
  98. GRB 250905A: Swift/UVOT Upper Limits
  99. GRB250904A: Liverpool Telescope upper limits
  100. GRB 250905A: Enhanced Swift-XRT position

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