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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"

14814 results found.

  1. IPN triangulation of GRB 251016B
  2. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  3. EP#01709247298: Swift-XRT counterpart detection
  4. GRB 251013C: further SAO RAS optical observations
  5. GRB 251013C: ISON-Castelgrande observatory optical observations
  6. GRB 251022A: MASTER OT detection
  7. GRB 251022A: DDOTI Optical Detection
  8. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  9. EP251023a: NOT optical counterpart detection
  10. EP251023a: GSP Optical Counterpart Detection
  11. EP251023a: Einstein Probe detection of an X-ray transient
  12. GRB 251022A: GOTO optical counterpart detection
  13. GRB 251023A: Fermi GBM Final Localization Correction
  14. GRB 251022A: Fermi-LAT detection
  15. GRB 251016B: Fermi GBM Detection
  16. GRB 251022A: Fermi GBM Final Real-time Localization
  17. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  18. EP251021b: BOOTES-7 optical upper limit
  19. EP251021b: Einstein Probe detection of a fast X-ray transient
  20. GRB 250911A: MAXI/GSC detection
  21. GRB 251016A: SVOM/ECLAIRs refined analysis
  22. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  23. GRB 251016A: HXMT/HE detection
  24. GRB 251016A: Swift-XRT afterglow detection
  25. GRB 251017A: Swift/UVOT Detection
  26. GRB 251016A: Swift/UVOT Detection
  27. GRB 251018A: Swift/UVOT Detection
  28. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  29. GRB 251018A: MASTER OT detection
  30. GRB 251018A: TRT optical afterglow detection
  31. GRB 251018A: Swift detection of a burst with an optical counterpart
  32. GRB 251018A: Fermi GBM Final Real-time Localization
  33. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  34. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  35. GRB 251017A: J-band detection with WINTER
  36. GRB 251017A: Glowbug gamma-ray detection
  37. GRB 251017A: JinShan observations of the optical afterglow
  38. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  39. GRB 251016A: AstroSat CZTI detection of a short burst
  40. GRB 251017A: COLIBRÍ Early Afterglow Detection
  41. GRB 251016B: AstroSat CZTI detection
  42. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  43. GRB 251017A: Swift detection of a burst with an optical counterpart
  44. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  45. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  46. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  47. GRB 251016B: Fermi GBM Final Real-time Localization
  48. GRB 251016A: BOOTES-6/DPRT optical upper limit
  49. GRB 251016A: Glowbug gamma-ray detection of a short burst
  50. GRB 251013C: VLA detection
  51. sb25101602: Swift-XRT counterpart detection
  52. GRB 251016A: Fermi GBM Final Localization
  53. GRB 251016A: SVOM detection of a short burst
  54. GRB 251014B: PRIME J-band upper limit
  55. GRB 251013C: Kilonova-Catcher optical afterglow detection
  56. GRB 251013C: Swift/UVOT Detection
  57. Konus-Wind detection of GRB 251007A
  58. GRB 251013C: detection of a radio counterpart at 15.5GHz
  59. GRB 251015A: Fermi GBM Final Real-time Localization
  60. Swift Trigger 1404295: possible GRB 251015A
  61. GRB 251014D: BOOTES-6/DPRT optical upper limit
  62. GRB 251014D: Swift-XRT afterglow detection
  63. IceCube-251014A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 251014D: Swift detection of a burst
  65. GRB 251014A: PRIME near-infrared upper limits
  66. GRB 251014C: Fermi GBM Final Localization
  67. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  68. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  69. GRB 251012A: Glowbug gamma-ray detection of a likely short burst
  70. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  71. GRB 251013C: Early and late-time optical counterpart detection by LCO
  72. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  73. GRB 251013A: CALET Gamma-Ray Burst Monitor detection
  74. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  75. GRB 251013C: EP-FXT counterpart detection
  76. GRB 251013C: AstroSat CZTI detection
  77. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  78. GRB 251013C: ALMA detection
  79. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  80. GRB 251013C: DDOTI detection of the optical afterglow
  81. GRB 251014A: Swift detection of a possibly-short burst
  82. GRB 251014A: Fermi GBM Final Real-time Localization
  83. GRB 251013C: Swift-XRT counterpart detection
  84. GRB 251013C: GOTO optical afterglow detection
  85. GRB 251013C: LCO optical afterglow detection
  86. GRB 251013C: NOT spectroscopic redshift z = 0.572
  87. GRB 251013C: LAST detection of optical counterpart
  88. GRB 251013C: BOOTES-6 early optical detection
  89. GRB 251013D: Fermi GBM Final Real-time Localization
  90. GRB 251013C: SVOM detection of a burst
  91. GRB 251013C: Fermi GBM Final Real-time Localization
  92. GRB 251013B: Fermi GBM Final Real-time Localization
  93. GRB 251013A: Fermi GBM Final Real-time Localization
  94. GRB 251011B inspection: MASTER orphan GRB detection
  95. GRB 251011A: Insight-HXMT detection
  96. GRB 251012A: Fermi GBM Final Real-time Localization
  97. GRB 251011C: Fermi GBM Final Real-time Localization
  98. GRB 251010A: AstroSat CZTI detection
  99. GRB 251011A: AstroSat CZTI detection
  100. GRB 251009B: SVOM/GRM observation of short GRB

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