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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"
  1. GRB 260718A: SVOM/VT optical upper limits
  2. GRB 260718A: SVOM/VT optical upper limits from VHF data
  3. GRB 260718A: SVOM detection of a burst
  4. GRB 260714B: SVOM/GRM observation
  5. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  6. GRB 260714B: GECAM-B observation of a burst
  7. GRB 260618B: EP-FXT follow-up observation upper limit
  8. GRB 260714B: COLIBRÍ optical counterpart candidate
  9. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  10. SVOM sb26071506: Global MASTER-Net observations report
  11. sb26071506: SVOM detection of a X-ray transient
  12. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  13. GRB 260715A: Fermi GBM Final Real-time Localization
  14. EP260703a: SVOM/ECLAIRs Upper Limit
  15. GRB 260710A: AstroSat CZTI detection
  16. GRB 260709A: AstroSat CZTI detection
  17. GRB 260714B: AstroSat CZTI detection
  18. GRB 260714B: Fermi-LAT detection
  19. GRB 260714B: Fermi GBM Detection
  20. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  21. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  22. GRB 260714B: Fermi GBM Final Real-time Localization
  23. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  24. GRB 260706A: ATCA detection of possible radio counterpart
  25. GRB 260705A: ATCA radio observations
  26. GRB 260714A: Fermi GBM Final Real-time Localization
  27. EP260713a: Einstein Probe detection of an X-ray transient
  28. GRB 260619A: SVOM/VT continuous optical observations
  29. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  30. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  31. EP260623a: KAIT optical observations
  32. EP260711a: EP-FXT follow-up observation
  33. GRB 260708A: GRANDMA Optical Observations
  34. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  35. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  36. GRB 260710A: Insight-HXMT/HE detection
  37. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  38. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  39. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 260708A: LCO optical observations
  41. EP260711a: Einstein Probe detection of an X-ray transient
  42. GRB 260710A: Fermi GBM Detection
  43. GRB 260709A: SVOM/GRM detection
  44. GRB 260709A: GECAM-B observation
  45. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  46. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  47. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  48. GRB 260705C: AstroSat CZTI detection
  49. GRB 260710A: Fermi GBM Final Real-time Localization
  50. GRB 260708A: Glowbug gamma-ray detection
  51. GRB 260704A: SVOM/ECLAIRs refined analysis
  52. GRB 260706A : GRANDMA Upper limits
  53. GRB 260708A: Kilonova-Catcher optical afterglow detection
  54. GRB 260708A: GECAM-B observation of a burst
  55. IceCube-260708A: One candidate from the Zwicky Transient Facility
  56. GRB 260708A: Fermi-GBM observation
  57. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  58. IceCube Alert 260709A: Global MASTER-Net observations report
  59. GRB 260709A: Fermi GBM Final Real-time Localization
  60. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  61. LAT GRB260708.42: Global MASTER-Net observations report
  62. GRB260708B: MAXI/GSC detection
  63. GRB 260708A: Fermi-LAT detection
  64. GRB 260705B: SVOM/GRM observation
  65. GRB 260708A: Fermi-GBM detection
  66. GRB 260706A: Further EP-FXT follow-up observation
  67. GRB 260706A: SVOM/VT optical upper limits
  68. EP260707a (by EP-FXT): NOT optical upper limit
  69. EP260707a is not a real source
  70. EP260707a: LCOGT Optical Upper Limit
  71. EP260707a: TRT optical upper limit
  72. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  73. EP260707a: Einstein Probe detection of an X-ray transient
  74. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  75. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  76. GRB 260705C: Glowbug gamma-ray detection of a short burst
  77. GRB 260706A: SVOM/ECLAIRs refined analysis
  78. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  79. GRB 260706A: SVOM/GRM observation
  80. GRB 260706A: REM optical/NIR observations
  81. IceCube-260704A: No candidates from the Zwicky Transient Facility
  82. GRB 260706A: LCO optical upper limit
  83. GRB 260706A: EP-FXT follow-up observation
  84. GRB 260707A: Fermi GBM Final Real-time Localization
  85. The EP-WXT trigger 01709274151 is likely a flaring star
  86. The EP-WXT trigger 01709274141 is likely a flaring star
  87. GRB 260706A: Fermi GBM Observation
  88. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  89. IPN triangulation of GRB 260627A
  90. GRB 260705A: SVOM/ECLAIRs refined analysis
  91. GRB 260706A: SVOM detection of a burst
  92. GRB 260706A: Fermi GBM Final Real-time Localization
  93. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  94. The EP-WXT trigger 01709274014 is likely a flaring star
  95. IceCube260704A: OHP/T193 optical observations
  96. GRB 260705A: LCO optical upper limits
  97. GRB 260704A: NOT optical upper limits
  98. GRB 260705C: Fermi GBM Final Localization
  99. GRB 260705B: Fermi GBM Final Real-time Localization
  100. Fermi GBM Sub-Threshold Detection of GRB 260705A

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