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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"

35321 results found.

  1. GRB 250920B: Swift-XRT refined Analysis
  2. GRB 250920B: SVOM/C-GFT optical observations
  3. GRB 250920C: GOTO optical counterpart candidate
  4. GRB 250919A / EP250919a: LCO optical observation
  5. Konus-Wind detection of GRB 250919A
  6. GRB 250920C: Swift detection of a burst
  7. GRB 250920C: Fermi GBM Final Real-time Localization
  8. Swift GRB 250920B: Global MASTER-Net observations report
  9. GRB 250919A / EP250919a: Insight-HXMT detection
  10. GRB 250920A: AstroSat CZTI detection
  11. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  12. GRB 250920B: Fermi GBM Final Real-time Localization
  13. GRB 250920A: BALROG localization (Fermi Trigger 780029651 / GRB 250920121)
  14. GRB 250920A: Fermi GBM Final Localization
  15. GRB 250919A/EP250919a: SVOM/VT optical observation
  16. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  17. GRB 250916A: Mondy R-band optical observations
  18. GRB 250919A: Glowbug gamma-ray detection
  19. GRB 250919A: Fermi GBM Observation
  20. Fermi GRB 250918A: Global MASTER-Net observations report
  21. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  22. GRB 250918A: SVOM/GRM observation
  23. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  24. GRB 250919A: Swift-XRT afterglow detection
  25. GRB 250919A: Fermi-LAT detection
  26. EP250919a/GRB 250919A: Gemini/GMOS-S spectroscopic redshift z = 1.145
  27. GRB 250919A: SVOM/GRM observation of a very bright GRB
  28. GRB 250919A: BALROG localization (Fermi Trigger 779934537 / GRB 250919020)
  29. EP250919a: Einstein Probe detection of an X-ray transient
  30. GRB 250916A: Fermi GBM Observation
  31. Fermi GRB 250919A: Global MASTER-Net observations report
  32. GRB 250919A: Fermi GBM Final Real-time Localization
  33. GRB 250916A: KAIT optical observations
  34. GRB 250917B: VLT/HAWK-I near-infrared observations
  35. GRB 250916A: NuSTAR detection of the prompt emission
  36. GRB 250916A: further SAO RAS optical observations
  37. GRB 250912A: SVOM/ECLAIRs refined analysis
  38. GRB 250917B: Swift-BAT refined analysis
  39. GRB 250918A: BALROG localization (Fermi Trigger 779891543 / GRB 250918522)
  40. GRB 250918A: Fermi GBM Final Real-time Localization
  41. GRB 250917B: Swift/UVOT Upper Limits
  42. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  43. GRB 250916A: Swift-XRT observations
  44. GRB 250916A: MAO/AZT-22 optical observations
  45. GRB 250916A: SAO RAS optical observations
  46. GRB 250916A : GIT optical observations
  47. GRB 250916A: Glowbug gamma-ray detection
  48. GRB250917B: WFST optical observations
  49. GRB 250916A: Swift ToO observations
  50. GRB 250917B: Fermi GBM Observation
  51. GRB 250917B: Swift-XRT observations
  52. Fermi GRB 250917B: Global MASTER-Net observations report
  53. GRB 250917B: Swift detection of a short burst
  54. GRB 250916A: GOTO optical counterpart candidate
  55. GRB 250917B: Fermi GBM Final Real-time Localization
  56. GRB 250917A: Fermi GBM Final Real-time Localization
  57. GRB 250916A: AstroSat CZTI detection of a bright long burst
  58. GRB 250910A: SVOM/ECLAIRs refined analysis
  59. Fermi GRB 250916A: Global MASTER-Net observations report
  60. GRB 250916A: Fermi GBM Final Real-time Localization
  61. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  62. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  63. GRB 250912A: Swift-XRT observations
  64. GRB250912A: VLT/HAWK-I follow-up observations
  65. GRB 250912A: VLT observations
  66. GRB 250912A: Fermi GBM Observation
  67. GRB 250911A: Insight-HXMT detection
  68. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  69. GRB 250912A:SVOM/VT optical upper limit
  70. GRB 250912A: LCO optical upper limit
  71. Fermi GRB 250912A: Global MASTER-Net observations report
  72. GRB 250912A: SVOM detection of a burst
  73. GRB 250912A: Fermi GBM Final Real-time Localization
  74. EP250911a: Upper limit from Fermi-GBM Observations
  75. GRB 250911A: GECAM-B detection
  76. GRB 250911A: Swift-BAT refined analysis
  77. GRB 250910B: SVOM/GRM observation
  78. GRB 250911A: MASTER optical counterpart observations
  79. EP250911a: SAO RAS optical observations
  80. GRB 250911A: Swift-XRT refined Analysis
  81. GRB 250910C: Fermi GBM Final Localization Correction
  82. GRB 250911A: Swift/UVOT Detection
  83. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  84. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  85. GRB 250909B: Insight-HXMT detection
  86. GRB 250909B: SVOM/GRM observation
  87. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  88. Fermi GRB 250910B: Global MASTER-Net observations report
  89. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  90. GRB 250903A: SVOM/ECLAIRs refined analysis
  91. GRB 250911A: Enhanced Swift-XRT position
  92. GRB 250911A: Swift-XRT observations
  93. GRB 250911A: COLIBRÍ optical counterpart candidate
  94. GRB 250911A: Swift detection of a burst
  95. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  96. GRB 250910B: Fermi GBM Final Real-time Localization
  97. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  98. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  99. GRB 250909B: AstroSat CZTI detection of a long burst
  100. GRB 250910A: SVOM/VT optical upper limit

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