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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"

32489 results found.

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

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