Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

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"

28222 results found.

  1. GRB 251028A: MAXI/GSC detection
  2. GRB 251028A: Fermi GBM Final Real-time Localization
  3. GRB 251025B: Swift-XRT confirmation of fading
  4. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  5. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  6. GRB 251025C: Glowbug gamma-ray detection
  7. GRB 251023B: Swift-UVOT Upper Limits
  8. Konus-Wind detection of GRB 251022A
  9. GRB 251027A: Swift-XRT observations
  10. GRB 251026B: Swift ToO observations
  11. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  12. GRB 251025B: Kilonova-Catcher optical afterglow detection
  13. Konus-Wind detection of GRB 251016A (short/hard)
  14. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  15. GRB 251027A: SVOM detection of a faint burst
  16. GRB 251025C: AstroSat CZTI detection
  17. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  18. GRB 251026A: Swift-XRT observations
  19. GRB 251025B: OHP/T193 optical detection
  20. GRB 251025B: J-band detection with WINTER
  21. GRB 251026B: Fermi GBM Final Localization
  22. GRB 251026A: SVOM detection of a long burst
  23. GRB 251025B: SVOM/VT optical bump
  24. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  25. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  26. GRB 251025C: Fermi GBM Final Real-time Localization
  27. Konus-Wind detection of GRB 251016B
  28. GRB 251024A: Swift/UVOT Upper Limits
  29. GRB 251025B: Swift-XRT afterglow detection
  30. GRB 251024A: Swift-XRT refined Analysis
  31. GRB 251025B: SVOM/VT optical observations with VHF data
  32. GRB 251025B: MASTER OT detection
  33. GRB 251025B: SVOM/C-GFT optical counterpart detection
  34. GRB 251025B: SVOM detection of a burst
  35. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  37. GRB 251025A: SVOM detection of a faint burst
  38. GRB 251003A: VLA Detection
  39. GRB 251024A: Enhanced Swift-XRT position
  40. GRB 251023C: Glowbug gamma-ray detection
  41. GRB 251024A: LCOGT Optical Afterglow Detection
  42. GRB 251022A: KAIT optical observations
  43. GRB 251024A: Swift detection of a burst
  44. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  45. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  46. EP251023a: MAO/AZT-22 optical observations
  47. EP251023a: OHP/T193 optical observations
  48. GRB 251023C: AstroSat CZTI detection
  49. GRB 251022A: Swift-XRT detection of GOTO25iym
  50. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  51. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  52. EP251023a: GROWTH-India Telescope optical observations
  53. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  54. GRB 251023A: Glowbug gamma-ray detection
  55. GRB 251023B: Glowbug gamma-ray detection
  56. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  57. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  58. IPN triangulation of GRB 251016B
  59. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  60. EP#01709247298: Swift-XRT counterpart detection
  61. GRB 251013C: further SAO RAS optical observations
  62. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  63. GRB 251013C: ISON-Castelgrande observatory optical observations
  64. GRB 251022A: MASTER OT detection
  65. GRB 251022A: DDOTI Optical Detection
  66. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  67. EP251023a: NOT optical counterpart detection
  68. EP251023a: GSP Optical Counterpart Detection
  69. EP251023a: Einstein Probe detection of an X-ray transient
  70. EP/WXT 01709247295: GOTO optical afterglow candidate.
  71. GRB 251022A: GOTO optical counterpart detection
  72. GRB 251023A: Fermi GBM Final Localization Correction
  73. GRB 251022A: Fermi-LAT detection
  74. GRB 251016B: Fermi GBM Detection
  75. GRB 251022A: Tiled Swift observations
  76. GRB 251022A: Fermi GBM Final Real-time Localization
  77. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  78. EP251021b: BOOTES-7 optical upper limit
  79. EP251021b: Einstein Probe detection of a fast X-ray transient
  80. GRB 250911A: MAXI/GSC detection
  81. GRB 251017A : RAPAS follow-up observations
  82. GRB 251018A: Fermi GBM Observation
  83. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  84. GRB 251018A: Swift-XRT refined Analysis
  85. GRB 251018A: Enhanced Swift-XRT position
  86. GRB 251016A: HXMT/HE detection
  87. GRB 251016A: Swift-XRT afterglow detection
  88. GRB 251017A: Swift/UVOT Detection
  89. GRB 251016A: Swift/UVOT Detection
  90. GRB 251018A: Swift/UVOT Detection
  91. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  92. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  93. GRB 251016A: VLT/FORS2 Optical Observation
  94. GRB 251017A: Swift-XRT refined Analysis
  95. GRB 251018A: MASTER OT detection
  96. GRB 251018A: TRT optical afterglow detection
  97. GRB 251018A: Swift detection of a burst with an optical counterpart
  98. GRB 251018A: Fermi GBM Final Real-time Localization
  99. GRB 251017A: OHP/T193 i-band observations
  100. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov