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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"

14815 results found.

  1. GRB 251013C: Chandra X-ray observations and jet break detection
  2. GRB 251111A: SVOM/VT optical observations with VHF data
  3. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  4. GRB 251111A: SVOM detection of a soft burst
  5. GRB 251105B: Insight-HXMT/HE detection
  6. GRB 251106B: Insight-HXMT detection
  7. GRB 251105A: AstroSat CZTI detection
  8. GRB 251108A: Fermi GBM Final Localization Correction
  9. IPN triangulation of GRB 251105B (possible sGRB with EE)
  10. GRB 251106A: Swift-XRT afterglow detection
  11. Fermi GBM Sub-Threshold Detection of GRB 251106A
  12. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  13. GRB 251106A: SVOM detection of a burst
  14. GRB 251103B: AstroSat CZTI detection
  15. GRB 251025C: TERI Gamma-ray detection
  16. GRB 251016B: TERI Gamma-ray detection
  17. GRB 251016A: TERI Gamma-ray detection of a short burst
  18. GRB 250920C: TERI Gamma-ray detection
  19. GRB 251105C: Fermi GBM Final Localization Correction
  20. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  21. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  22. Fermi GBM Sub-Threshold Detection of GRB 251105B
  23. GRB 251105A: Fermi GBM Final Real-time Localization
  24. GRB 251104A: SVOM detection of a burst
  25. GRB 251028A: Insight-HXMT/HE detection
  26. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  27. GRB 251103A: WFST optical observations
  28. GRB 251103A: Xinglong 2.16m optical detection
  29. GRB 251103A: Insight-HXMT detection
  30. GRB 251103B: Nanshan/HMT optical upper limit
  31. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  32. GRB 251103A: J-band detection with WINTER
  33. GRB 251103A: Kilonova-Catcher optical afterglow detection
  34. GRB 251103B: Swift detection of a burst
  35. GRB 251103B: Fermi GBM Final Real-time Localization
  36. GRB 251103A: Swift/UVOT Detection
  37. GRB 251103A: Swift-XRT afterglow detection
  38. EP251102a: Einstein Probe detection of a fast X-ray transient
  39. GRB 251103A: GOTO optical afterglow detection
  40. GRB 251102A: AstroSat CZTI detection
  41. GRB 251103A: NOT spectroscopic redshift z = 0.76
  42. GRB 251103A: BOOTES-2/TELMA optical afterglow
  43. GRB 251103A: LCO optical afterglow detection
  44. GRB 251103A: Fermi GBM Final Localization
  45. GRB 251103A: SVOM detection of a bright burst
  46. GRB 251102B: Fermi GBM Final Real-time Localization
  47. GRB 251102A: Fermi GBM Final Real-time Localization
  48. Konus-Wind detection of GRB 251028A
  49. GRB 251031A: Fermi GBM Final Real-time Localization
  50. GRB 251028A: GECAM-B detection
  51. GRB 251026B: LBT near-infrared observations
  52. GRB 250926B: VZLUSAT-2 detection
  53. GRB 250926A: VZLUSAT-2 detection
  54. GRB 250925A: VZLUSAT-2 detection
  55. GRB 251028B: Glowbug gamma-ray detection
  56. GRB 251028A: Glowbug gamma-ray detection
  57. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  58. GRB 251028B: Fermi GBM Final Localization Correction
  59. GRB251026B: PRIME H-band upper limit
  60. GRB251025B: 3.6m DOT Optical Observations
  61. GRB 251028A: MAXI/GSC detection
  62. GRB 251028A: Fermi GBM Final Real-time Localization
  63. GRB 251025C: Glowbug gamma-ray detection
  64. GRB 251023B: Swift-UVOT Upper Limits
  65. Konus-Wind detection of GRB 251022A
  66. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  67. GRB 251025B: Kilonova-Catcher optical afterglow detection
  68. Konus-Wind detection of GRB 251016A (short/hard)
  69. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  70. GRB 251027A: SVOM detection of a faint burst
  71. GRB 251025C: AstroSat CZTI detection
  72. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  73. GRB 251025B: OHP/T193 optical detection
  74. GRB 251025B: J-band detection with WINTER
  75. GRB 251026B: Fermi GBM Final Localization
  76. GRB 251026A: SVOM detection of a long burst
  77. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  78. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  79. GRB 251025C: Fermi GBM Final Real-time Localization
  80. Konus-Wind detection of GRB 251016B
  81. GRB 251025B: Swift-XRT afterglow detection
  82. GRB 251025B: SVOM/VT optical observations with VHF data
  83. GRB 251025B: MASTER OT detection
  84. GRB 251025B: SVOM/C-GFT optical counterpart detection
  85. GRB 251025B: SVOM detection of a burst
  86. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  87. GRB 251025A: SVOM detection of a faint burst
  88. GRB 251003A: VLA Detection
  89. GRB 251023C: Glowbug gamma-ray detection
  90. GRB 251024A: LCOGT Optical Afterglow Detection
  91. GRB 251024A: Swift detection of a burst
  92. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  93. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  94. GRB 251023C: AstroSat CZTI detection
  95. EP251023b/GRB 251023B: JinShan optical observation
  96. GRB 251022A: Swift-XRT detection of GOTO25iym
  97. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  98. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  99. GRB 251023A: Glowbug gamma-ray detection
  100. GRB 251023B: Glowbug gamma-ray detection

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