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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"

32494 results found.

  1. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  2. EP260723a: SVOM/ECLAIRs Upper Limit
  3. GRB 260727A: GOTO early optical upper limit
  4. GRB 260727A: AstroSat CZTI detection
  5. GRB 260727A: Kilonova-Catcher optical upper limit
  6. GRB 260727A: LCO optical upper limits
  7. Fermi GRB 260726A: Global MASTER-Net observations report
  8. GRB 260726A: SVOM detection of a burst
  9. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  10. EP260723a: further EP-FXT follow-up observation
  11. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  12. GRB 260616A: cubesat Avion detection
  13. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  14. GRB 260602B: cubesat Avion detection
  15. GRB 260601A: cubesat Avion detection
  16. EP260723a: EP-FXT follow-up observation
  17. IPN triangulation of GRB 260706B
  18. GRB 260718A: SVOM/ECLAIRs refined analysis
  19. EP260723a: SVOM/VT optical observation
  20. EP260723a: COLIBRÍ optical observations
  21. EP260723a: NOT optical conterpart confirmation
  22. EP260723a: Liverpool Telescope likely optical counterpart
  23. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  25. Konus-Wind detection of GRB 260721A
  26. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 260721A: NuSTAR detection of prompt emission
  28. Konus-Wind detection of GRB 260714B
  29. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  30. GRB 260705A: Retraction of optical counterpart
  31. GRB 260714B: Insight-HXMT/HE detection
  32. GRB 260718A: EP-FXT follow-up observation
  33. Fermi GRB 260718A: Global MASTER-Net observations report
  34. GRB 260718A: LCO optical upper limits
  35. GRB 260711A: SVOM/GRM observation
  36. GRB 260710A: SVOM/GRM observation
  37. GRB 260718A: Fermi GBM Observation
  38. GRB 260718A : GRANDMA and KNC upper limits
  39. GRB 260718A: SVOM/VT optical upper limits
  40. GRB 260718A: SVOM/VT optical upper limits from VHF data
  41. GRB 260718A: SVOM detection of a burst
  42. GRB 260714B: SVOM/GRM observation
  43. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  44. GRB 260714B: GECAM-B observation of a burst
  45. GRB 260618B: EP-FXT follow-up observation upper limit
  46. GRB 260714B: COLIBRÍ optical counterpart candidate
  47. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  48. SVOM sb26071506: Global MASTER-Net observations report
  49. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  50. EP260703a: SVOM/ECLAIRs Upper Limit
  51. GRB 260710A: AstroSat CZTI detection
  52. GRB 260709A: AstroSat CZTI detection
  53. GRB 260714B: AstroSat CZTI detection
  54. GRB 260714B: Fermi-LAT detection
  55. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  56. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  57. GRB 260706A: ATCA detection of possible radio counterpart
  58. GRB 260705A: ATCA radio observations
  59. GRB 260619A: SVOM/VT continuous optical observations
  60. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  61. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  62. EP260623a: KAIT optical observations
  63. EP260711a: EP-FXT follow-up observation
  64. GRB 260708A: GRANDMA Optical Observations
  65. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  66. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  67. GRB 260710A: Insight-HXMT/HE detection
  68. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  69. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  70. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 260708A: LCO optical observations
  72. GRB 260710A: Fermi GBM Detection
  73. GRB 260709A: SVOM/GRM detection
  74. GRB 260709A: GECAM-B observation
  75. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  76. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  77. GRB 260705C: AstroSat CZTI detection
  78. GRB 260708A: Glowbug gamma-ray detection
  79. GRB 260704A: SVOM/ECLAIRs refined analysis
  80. GRB 260706A : GRANDMA Upper limits
  81. GRB 260708A: Kilonova-Catcher optical afterglow detection
  82. GRB 260708A: GECAM-B observation of a burst
  83. IceCube-260708A: One candidate from the Zwicky Transient Facility
  84. GRB 260708A: Fermi-GBM observation
  85. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  86. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  87. GRB 260708A: Fermi-LAT detection
  88. GRB 260705B: SVOM/GRM observation
  89. GRB 260706A: Further EP-FXT follow-up observation
  90. GRB 260706A: SVOM/VT optical upper limits
  91. EP260707a (by EP-FXT): NOT optical upper limit
  92. EP260707a is not a real source
  93. EP260707a: LCOGT Optical Upper Limit
  94. EP260707a: TRT optical upper limit
  95. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  96. GRB 260705C: Glowbug gamma-ray detection of a short burst
  97. GRB 260706A: SVOM/ECLAIRs refined analysis
  98. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  99. GRB 260706A: SVOM/GRM observation
  100. GRB 260706A: REM optical/NIR observations

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