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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"

32508 results found.

  1. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  2. EP260727a: OHP/T193 optical observations
  3. Konus-Wind detection of GRB 260727A
  4. GRB 260726A: Liverpool Telescope optical observations
  5. GRB 260727A: Liverpool Telescope optical upper limits
  6. EP260727a: Liverpool Telescope confirmation of optical counterpart
  7. EP260727a: NUTTELA-TAO Early Optical Limits
  8. GRB 260727A: EP/FXT follow-up observations
  9. EP260727a: Einstein Probe detection of an X-ray transient
  10. GRB 260727A: Glowbug gamma-ray detection
  11. GRB 260726A: J-band upper limit with WINTER
  12. GRB 260727A: J-band upper limit with WINTER
  13. GRB 260726A: SVOM/VT optical candidate
  14. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  15. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  16. EP260723a: SVOM/ECLAIRs Upper Limit
  17. GRB 260727A: GOTO early optical upper limit
  18. GRB 260727A: AstroSat CZTI detection
  19. GRB 260727A: Kilonova-Catcher optical upper limit
  20. GRB 260727A: LCO optical upper limits
  21. Fermi GRB 260726A: Global MASTER-Net observations report
  22. GRB 260726A: SVOM detection of a burst
  23. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  24. EP260723a: further EP-FXT follow-up observation
  25. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  26. GRB 260616A: cubesat Avion detection
  27. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  28. GRB 260602B: cubesat Avion detection
  29. GRB 260601A: cubesat Avion detection
  30. EP260723a: EP-FXT follow-up observation
  31. IPN triangulation of GRB 260706B
  32. GRB 260718A: SVOM/ECLAIRs refined analysis
  33. EP260723a: SVOM/VT optical observation
  34. EP260723a: COLIBRÍ optical observations
  35. EP260723a: NOT optical conterpart confirmation
  36. EP260723a: Liverpool Telescope likely optical counterpart
  37. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  38. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  39. Konus-Wind detection of GRB 260721A
  40. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 260721A: NuSTAR detection of prompt emission
  42. Konus-Wind detection of GRB 260714B
  43. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  44. GRB 260705A: Retraction of optical counterpart
  45. GRB 260714B: Insight-HXMT/HE detection
  46. GRB 260718A: EP-FXT follow-up observation
  47. Fermi GRB 260718A: Global MASTER-Net observations report
  48. GRB 260718A: LCO optical upper limits
  49. GRB 260711A: SVOM/GRM observation
  50. GRB 260710A: SVOM/GRM observation
  51. GRB 260718A: Fermi GBM Observation
  52. GRB 260718A : GRANDMA and KNC upper limits
  53. GRB 260718A: SVOM/VT optical upper limits
  54. GRB 260718A: SVOM/VT optical upper limits from VHF data
  55. GRB 260718A: SVOM detection of a burst
  56. GRB 260714B: SVOM/GRM observation
  57. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  58. GRB 260714B: GECAM-B observation of a burst
  59. GRB 260618B: EP-FXT follow-up observation upper limit
  60. GRB 260714B: COLIBRÍ optical counterpart candidate
  61. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  62. SVOM sb26071506: Global MASTER-Net observations report
  63. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  64. EP260703a: SVOM/ECLAIRs Upper Limit
  65. GRB 260710A: AstroSat CZTI detection
  66. GRB 260709A: AstroSat CZTI detection
  67. GRB 260714B: AstroSat CZTI detection
  68. GRB 260714B: Fermi-LAT detection
  69. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  70. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  71. GRB 260706A: ATCA detection of possible radio counterpart
  72. GRB 260705A: ATCA radio observations
  73. GRB 260619A: SVOM/VT continuous optical observations
  74. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  75. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  76. EP260623a: KAIT optical observations
  77. EP260711a: EP-FXT follow-up observation
  78. GRB 260708A: GRANDMA Optical Observations
  79. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  80. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  81. GRB 260710A: Insight-HXMT/HE detection
  82. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  83. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260708A: LCO optical observations
  86. GRB 260710A: Fermi GBM Detection
  87. GRB 260709A: SVOM/GRM detection
  88. GRB 260709A: GECAM-B observation
  89. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  90. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  91. GRB 260705C: AstroSat CZTI detection
  92. GRB 260708A: Glowbug gamma-ray detection
  93. GRB 260704A: SVOM/ECLAIRs refined analysis
  94. GRB 260706A : GRANDMA Upper limits
  95. GRB 260708A: Kilonova-Catcher optical afterglow detection
  96. GRB 260708A: GECAM-B observation of a burst
  97. IceCube-260708A: One candidate from the Zwicky Transient Facility
  98. GRB 260708A: Fermi-GBM observation
  99. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  100. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event

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