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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"

3137 results found.

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

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