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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"

2844 results found.

  1. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  2. GRB 251025C: AstroSat CZTI detection
  3. Fermi GRB 251026B: Global MASTER-Net observations report
  4. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  5. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  6. GRB 251023C: AstroSat CZTI detection
  7. EP251023b: Global MASTER-Net observations report
  8. IPN triangulation of GRB 251016B
  9. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  10. Fermi GRB 251023A: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  12. GRB 251016A: Fermi GBM Observation
  13. GRB 251018A: Fermi GBM Observation
  14. IceCube-251018A: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  16. GRB 251016A: AstroSat CZTI detection of a short burst
  17. GRB 251016B: AstroSat CZTI detection
  18. GRB 251017A: Swift detection of a burst with an optical counterpart
  19. Fermi GRB 251016A: Global MASTER-Net observations report
  20. GRB 251013C: SVOM/ECLAIRs refined analysis
  21. GRB 251013D: Fermi GBM Observation
  22. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  23. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  24. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  25. GRB 251013C: AstroSat CZTI detection
  26. Fermi trigger No 782044789: Global MASTER-Net observations report
  27. Fermi GRB 251013C: Global MASTER-Net observations report
  28. GRB 251013C: BOOTES-6 early optical detection
  29. GRB 251013C: SVOM/VT optical observation
  30. GRB 251013C: SVOM detection of a burst
  31. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  32. GRB 251010A: AstroSat CZTI detection
  33. GRB 251011A: AstroSat CZTI detection
  34. EP251006a: Global MASTER-Net observations report
  35. IceCube Alert 251008A: Global MASTER-Net observations report
  36. GRB 251007A: AstroSat CZTI detection
  37. GRB 251007B: SVOM detection of a faint burst
  38. GRB 251006B/EP251006a: SVOM/VT optical candidate
  39. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  40. Fermi GRB 251006A: Global MASTER-Net observations report
  41. GRB 251005C: AstroSat CZTI detection
  42. GRB 251001A: AstroSat CZTI detection
  43. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  44. GRB 251002A: SVOM detection of a burst
  45. Fermi GRB 251002A: Global MASTER-Net observations report
  46. Fermi GRB 250929A: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  49. GRB 250926A: AstroSat CZTI detection
  50. GRB 250925A: Leavitt Observatory optical upper limit
  51. GRB 250924A: SAO RAS optical observations
  52. GRB 250924A: AstroSat CZTI detection
  53. GRB 250914A: AstroSat CZTI detection
  54. GRB 250920B: AstroSat CZTI detection
  55. GRB 250922C: AstroSat CZTI detection of a short burst
  56. Fermi trigger No 780156732: Global MASTER-Net observations report
  57. Swift GRB 250920C: Global MASTER-Net observations report
  58. Konus-Wind detection of GRB 250919A
  59. GRB 250920A: AstroSat CZTI detection
  60. EP250919a: Global MASTER-Net observations report
  61. Fermi GRB 250919A: Global MASTER-Net observations report
  62. GRB 250916A: SAO RAS optical observations
  63. GRB250917B: WFST optical observations
  64. GRB 250916A: AstroSat CZTI detection of a bright long burst
  65. Fermi GRB 250916A: Global MASTER-Net observations report
  66. Fermi GRB 250912A: Global MASTER-Net observations report
  67. EP250911a: Global MASTER-Net observations report
  68. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  69. Fermi GRB 250910B: Global MASTER-Net observations report
  70. EP250910a: Global MASTER-Net observations report
  71. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  72. GRB 250909B: AstroSat CZTI detection of a long burst
  73. GRB 250909A: AstroSat CZTI detection
  74. The EP-WXT trigger EP250908a/01709240652 is not a real source
  75. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  76. IceCube Alert 250905.84: Global MASTER-Net observations report
  77. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  80. EP250901a: Mondy, Assy and SAO RAS optical limits
  81. GRB 250902B: AstroSat CZTI detection
  82. Fermi GRB 250902B: Global MASTER-Net observations report
  83. EP250901a: Swift-XRT observations
  84. GRB 250901A: LCO optical upper limit
  85. EP250827b: Swift observations of AT 2025wkm
  86. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  87. EP250901a: Global MASTER-Net observations report
  88. GRB 250830C: AstroSat CZTI detection of a long burst
  89. EP250831a: Global MASTER-Net observations report
  90. EP250830a: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  94. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  95. GRB 250826A: Fermi GBM Final Real-time Localization
  96. Fermi GRB 250824B: Global MASTER-Net observations report
  97. GRB 250821B: AstroSat CZTI detection
  98. GRB 250819A: AstroSat CZTI detection
  99. LIGO/Virgo/KAGRA S250818k: GRAWITA TNG NIR observations of AT2025ulz
  100. GRB 250821C: Fermi GBM Final Real-time Localization

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