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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"

27784 results found.

  1. GRB 251028A: Glowbug gamma-ray detection
  2. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  3. GRB 251028B: Fermi GBM Final Localization Correction
  4. GRB251026B: PRIME H-band upper limit
  5. GRB251025B: 3.6m DOT Optical Observations
  6. GRB 251028A: MAXI/GSC detection
  7. GRB 251028A: Fermi GBM Final Real-time Localization
  8. GRB 251025B: Swift-XRT confirmation of fading
  9. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  10. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  11. GRB 251025C: Glowbug gamma-ray detection
  12. GRB 251023B: Swift-UVOT Upper Limits
  13. Konus-Wind detection of GRB 251022A
  14. GRB 251027A: Swift-XRT observations
  15. GRB 251022A: SVOM/GRM observation
  16. GRB 251026B: Swift ToO observations
  17. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  18. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  19. GRB 251017A: INASAN-Kislovodsk optical observations
  20. GRB 251025B: Kilonova-Catcher optical afterglow detection
  21. Konus-Wind detection of GRB 251016A (short/hard)
  22. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  23. GRB 251027A: SVOM detection of a faint burst
  24. GRB 251025C: AstroSat CZTI detection
  25. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  26. GRB 251026A: Swift-XRT observations
  27. GRB 251025B: OHP/T193 optical detection
  28. GRB 251025B: J-band detection with WINTER
  29. GRB 251026B: Fermi GBM Final Localization
  30. GRB 251026A: SVOM detection of a long burst
  31. GRB 251025B: SVOM/VT optical bump
  32. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  33. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  34. GRB 251025C: Fermi GBM Final Real-time Localization
  35. Konus-Wind detection of GRB 251016B
  36. GRB 251024A: Swift/UVOT Upper Limits
  37. GRB 251025B: Swift-XRT afterglow detection
  38. GRB 251024A: Swift-BAT refined analysis
  39. GRB 251024A: Swift-XRT refined Analysis
  40. GRB 251025B: SVOM/VT optical observations with VHF data
  41. GRB 251025B: MASTER OT detection
  42. GRB 251025B: SVOM/C-GFT optical counterpart detection
  43. GRB 251025B: SVOM detection of a burst
  44. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 251025A: SVOM detection of a faint burst
  46. GRB 251003A: VLA Detection
  47. GRB 251024A: Enhanced Swift-XRT position
  48. GRB 251023C: Glowbug gamma-ray detection
  49. GRB 251024A: LCOGT Optical Afterglow Detection
  50. GRB 251024A: Swift detection of a burst
  51. Swift GRB 251024A: Global MASTER-Net observations report
  52. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  53. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  54. GRB 251023C: AstroSat CZTI detection
  55. GRB 251022A: Swift-XRT detection of GOTO25iym
  56. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  57. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  58. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  59. GRB 251022A: Fermi GBM Observation
  60. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  61. GRB 251023A: Glowbug gamma-ray detection
  62. GRB 251023B: Glowbug gamma-ray detection
  63. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  64. IPN triangulation of GRB 251016B
  65. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  66. EP#01709247298: Swift-XRT counterpart detection
  67. GRB 251022A: MASTER OT detection
  68. GRB 251022A: DDOTI Optical Detection
  69. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  70. EP251023a: NOT optical counterpart detection
  71. EP251023a: GSP Optical Counterpart Detection
  72. EP251023a: Einstein Probe detection of an X-ray transient
  73. GRB 251022A: GOTO optical counterpart detection
  74. GRB 251023A: Fermi GBM Final Localization Correction
  75. GRB 251022A: Fermi-LAT detection
  76. GRB 251016B: Fermi GBM Detection
  77. GRB 251022A: Tiled Swift observations
  78. GRB 251022A: Fermi GBM Final Real-time Localization
  79. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  80. EP251021b: BOOTES-7 optical upper limit
  81. EP251021b: Einstein Probe detection of a fast X-ray transient
  82. GRB 250911A: MAXI/GSC detection
  83. GRB 251017A: COLIBRÍ optical observations of a late plateau
  84. GRB 251017A: Swift-BAT refined analysis
  85. GRB 251018A: Fermi GBM Observation
  86. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  87. GRB 251018A: Swift-XRT refined Analysis
  88. GRB 251018A: Enhanced Swift-XRT position
  89. GRB 251016A: HXMT/HE detection
  90. GRB 251016A: Swift-XRT afterglow detection
  91. GRB 251017A: Swift/UVOT Detection
  92. GRB 251016A: Swift/UVOT Detection
  93. GRB 251018A: Swift/UVOT Detection
  94. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  95. GRB 251016A: VLT/FORS2 Optical Observation
  96. GRB 251017A: COLIBRÍ photometric redshift
  97. GRB 251017A: Swift-XRT refined Analysis
  98. GRB 251018A: MASTER OT detection
  99. GRB 251018A: TRT optical afterglow detection
  100. Swift GRB 251018A: Global MASTER-Net observations report

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