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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"

3136 results found.

  1. GRB 260127B: GOTO candidate optical counterpart
  2. GRB 260127A: LCO optical afterglow discovery
  3. GRB 260120A: AstroSat CZTI detection
  4. GRB 260120B: AstroSat CZTI detection
  5. SVOM GRB260121.06: Global MASTER-Net observations report
  6. GRB 260120B: Swift detection of a burst
  7. EP260119A: Mondy I-Band Observations
  8. GRB 251202A: further radio observations with the VLA
  9. SVOM GRB260119.90: Global MASTER-Net observations report
  10. GRB 260115A: AstroSat CZTI detection
  11. EP260116a: Global MASTER-Net observations report
  12. Fermi GRB 260115A: Global MASTER-Net observations report
  13. GRB 260114A: Swift detection of a short burst
  14. GRB 251230A: Mondy Optical Observations
  15. Fermi GRB 260111A: Global MASTER-Net observations report
  16. FRB 20251229A: COLIBRÍ optical upper limits
  17. GRB 260105B: Fermi GBM Final Real-time Localization
  18. GRB 260104B: Fermi GBM Final Localization
  19. SVOM GRB260103.08: Global MASTER-Net observations report
  20. EP260101a: Einstein Probe detection of an X-ray transient
  21. GRB 251231A: Fermi GBM Final Real-time Localization
  22. Fermi GRB 251228A: Global MASTER-Net observations report
  23. GRB 251228A: Fermi GBM Final Real-time Localization
  24. SVOM GRB251227.07: Global MASTER-Net observations report
  25. GRB 251221A: Swift-BAT refined analysis
  26. EP251221a: Global MASTER-Net observations report
  27. GRB 251222A: SVOM detection of a long burst
  28. EP 251220a: GOTO optical counterpart detection
  29. Fermi GRB 251217A: Global MASTER-Net observations report
  30. Fermi GRB 251216A: Global MASTER-Net observations report
  31. Fermi GRB 251215A: Global MASTER-Net observations report
  32. GRB 251214D: AstroSat CZTI detection of a long burst
  33. GRB 251213A: AstroSat CZTI detection
  34. GRB 251214A: AstroSat CZTI detection
  35. GRB 251215A: Fermi GBM Final Real-time Localization
  36. GRB 251214B: SVOM/C-GFT optical observations
  37. EP251212a: Global MASTER-Net observations report
  38. EP251212a / GRB 251212A: AstroSat CZTI detection
  39. GRB 251211B: AstroSat CZTI detection
  40. Fermi GRB 251211B: Global MASTER-Net observations report
  41. GRB 251209A: AstroSat CZTI detection
  42. IceCube Alert 251210.46: Global MASTER-Net observations report
  43. GRB 251208A: AstroSat CZTI detection
  44. GRB 251208A: Fermi GBM Final Real-time Localization
  45. GRB 251205A: FTW optical and NIR observations
  46. GRB 251205A: Swift detection of a burst with an optical afterglow
  47. GRB 251203A: SVOM/GRM observation
  48. GRB 251203A: AstroSat CZTI detection
  49. GRB 251201B: Insight-HXMT/HE detection
  50. EP251202a / GRB251202A: AstroSat CZTI detection
  51. GRB 251129B: AstroSat CZTI detection
  52. EP251130a: continued NOT optical observations indicate steep fading phase
  53. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  54. GRB 251130B: AstroSat CZTI detection
  55. GRB 251128A: AstroSat CZTI detection
  56. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  57. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  58. Fermi GRB 251127A: Global MASTER-Net observations report
  59. GRB 251127A: Fermi GBM Final Real-time Localization
  60. EP251122a: Global MASTER-Net observations report
  61. GRB 251018A: FRAM-Auger optical detection
  62. Konus-Wind detection of GRB 251118C (EP251118a)
  63. LAT GRB251118.86: Global MASTER-Net observations report
  64. EP251118a: Einstein Probe detected of a fast X-ray transient
  65. GRB 251117A: AstroSat CZTI detection
  66. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  67. LAT GRB251117.51: Global MASTER-Net observations report
  68. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  69. GRB 251116D: AstroSat CZTI detection
  70. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  71. GRB 251116B: LCO optical upper limits
  72. SVOM GRB251116C: Global MASTER-Net observations report
  73. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  74. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  75. GRB 251113A: AstroSat CZTI detection
  76. GRB 251108C: AstroSat CZTI detection
  77. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  78. GRB 251013C: Chandra X-ray observations and jet break detection
  79. GRB 251105A: AstroSat CZTI detection
  80. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  81. Fermi trigger No 784279167: Global MASTER-Net observations report
  82. SVOM GRB251108.54: Global MASTER-Net observations report
  83. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  84. GRB 251103B: AstroSat CZTI detection
  85. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  86. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  87. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  88. Fermi GRB 251103A: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  90. GRB 251102A: AstroSat CZTI detection
  91. GRB 251103A: Fermi GBM Final Localization
  92. GRB 251102B: Fermi GBM Final Real-time Localization
  93. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  94. GRB 251025C: AstroSat CZTI detection
  95. Fermi GRB 251026B: Global MASTER-Net observations report
  96. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  97. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  98. GRB 251023C: AstroSat CZTI detection
  99. EP251023b: Global MASTER-Net observations report
  100. IPN triangulation of GRB 251016B

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