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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"

2850 results found.

  1. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  2. Fermi GRB 251103A: Global MASTER-Net observations report
  3. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  4. GRB 251102A: AstroSat CZTI detection
  5. GRB 251103A: Fermi GBM Final Localization
  6. GRB 251102B: Fermi GBM Final Real-time Localization
  7. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  8. GRB 251025C: AstroSat CZTI detection
  9. Fermi GRB 251026B: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  11. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  12. GRB 251023C: AstroSat CZTI detection
  13. EP251023b: Global MASTER-Net observations report
  14. IPN triangulation of GRB 251016B
  15. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  16. Fermi GRB 251023A: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  18. GRB 251016A: Fermi GBM Observation
  19. GRB 251018A: Fermi GBM Observation
  20. IceCube-251018A: Global MASTER-Net observations report
  21. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  22. GRB 251016A: AstroSat CZTI detection of a short burst
  23. GRB 251016B: AstroSat CZTI detection
  24. GRB 251017A: Swift detection of a burst with an optical counterpart
  25. Fermi GRB 251016A: Global MASTER-Net observations report
  26. GRB 251013C: SVOM/ECLAIRs refined analysis
  27. GRB 251013D: Fermi GBM Observation
  28. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  29. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  30. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  31. GRB 251013C: AstroSat CZTI detection
  32. Fermi trigger No 782044789: Global MASTER-Net observations report
  33. Fermi GRB 251013C: Global MASTER-Net observations report
  34. GRB 251013C: BOOTES-6 early optical detection
  35. GRB 251013C: SVOM/VT optical observation
  36. GRB 251013C: SVOM detection of a burst
  37. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  38. GRB 251010A: AstroSat CZTI detection
  39. GRB 251011A: AstroSat CZTI detection
  40. EP251006a: Global MASTER-Net observations report
  41. IceCube Alert 251008A: Global MASTER-Net observations report
  42. GRB 251007A: AstroSat CZTI detection
  43. GRB 251007B: SVOM detection of a faint burst
  44. GRB 251006B/EP251006a: SVOM/VT optical candidate
  45. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  46. Fermi GRB 251006A: Global MASTER-Net observations report
  47. GRB 251005C: AstroSat CZTI detection
  48. GRB 251001A: AstroSat CZTI detection
  49. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  50. GRB 251002A: SVOM detection of a burst
  51. Fermi GRB 251002A: Global MASTER-Net observations report
  52. Fermi GRB 250929A: Global MASTER-Net observations report
  53. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  55. GRB 250926A: AstroSat CZTI detection
  56. GRB 250925A: Leavitt Observatory optical upper limit
  57. GRB 250924A: SAO RAS optical observations
  58. GRB 250924A: AstroSat CZTI detection
  59. GRB 250914A: AstroSat CZTI detection
  60. GRB 250920B: AstroSat CZTI detection
  61. GRB 250922C: AstroSat CZTI detection of a short burst
  62. Fermi trigger No 780156732: Global MASTER-Net observations report
  63. Swift GRB 250920C: Global MASTER-Net observations report
  64. Konus-Wind detection of GRB 250919A
  65. GRB 250920A: AstroSat CZTI detection
  66. EP250919a: Global MASTER-Net observations report
  67. Fermi GRB 250919A: Global MASTER-Net observations report
  68. GRB 250916A: SAO RAS optical observations
  69. GRB250917B: WFST optical observations
  70. GRB 250916A: AstroSat CZTI detection of a bright long burst
  71. Fermi GRB 250916A: Global MASTER-Net observations report
  72. Fermi GRB 250912A: Global MASTER-Net observations report
  73. EP250911a: Global MASTER-Net observations report
  74. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  75. Fermi GRB 250910B: Global MASTER-Net observations report
  76. EP250910a: Global MASTER-Net observations report
  77. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  78. GRB 250909B: AstroSat CZTI detection of a long burst
  79. GRB 250909A: AstroSat CZTI detection
  80. The EP-WXT trigger EP250908a/01709240652 is not a real source
  81. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  82. IceCube Alert 250905.84: Global MASTER-Net observations report
  83. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  86. EP250901a: Mondy, Assy and SAO RAS optical limits
  87. GRB 250902B: AstroSat CZTI detection
  88. Fermi GRB 250902B: Global MASTER-Net observations report
  89. EP250901a: Swift-XRT observations
  90. GRB 250901A: LCO optical upper limit
  91. EP250827b: Swift observations of AT 2025wkm
  92. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  93. EP250901a: Global MASTER-Net observations report
  94. GRB 250830C: AstroSat CZTI detection of a long burst
  95. EP250831a: Global MASTER-Net observations report
  96. EP250830a: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  98. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate

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