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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. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  2. GRB 260710A: Insight-HXMT/HE detection
  3. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  4. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  5. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  6. GRB 260708A: LCO optical observations
  7. EP260711a: Einstein Probe detection of an X-ray transient
  8. GRB 260710A: Fermi GBM Detection
  9. GRB 260709A: SVOM/GRM detection
  10. GRB 260709A: GECAM-B observation
  11. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  12. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  13. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  14. GRB 260705C: AstroSat CZTI detection
  15. GRB 260710A: Fermi GBM Final Real-time Localization
  16. GRB 260708A: Glowbug gamma-ray detection
  17. GRB 260704A: SVOM/ECLAIRs refined analysis
  18. GRB 260706A : GRANDMA Upper limits
  19. GRB 260708A: Kilonova-Catcher optical afterglow detection
  20. GRB 260708A: GECAM-B observation of a burst
  21. IceCube-260708A: One candidate from the Zwicky Transient Facility
  22. GRB 260708A: Fermi-GBM observation
  23. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  24. IceCube Alert 260709A: Global MASTER-Net observations report
  25. GRB 260709A: Fermi GBM Final Real-time Localization
  26. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  27. LAT GRB260708.42: Global MASTER-Net observations report
  28. GRB260708B: MAXI/GSC detection
  29. GRB 260708A: Fermi-LAT detection
  30. GRB 260705B: SVOM/GRM observation
  31. GRB 260708A: Fermi-GBM detection
  32. GRB 260706A: Further EP-FXT follow-up observation
  33. GRB 260706A: SVOM/VT optical upper limits
  34. EP260707a (by EP-FXT): NOT optical upper limit
  35. EP260707a is not a real source
  36. EP260707a: LCOGT Optical Upper Limit
  37. EP260707a: TRT optical upper limit
  38. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  39. EP260707a: Einstein Probe detection of an X-ray transient
  40. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  41. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  42. GRB 260705C: Glowbug gamma-ray detection of a short burst
  43. GRB 260706A: SVOM/ECLAIRs refined analysis
  44. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  45. GRB 260706A: SVOM/GRM observation
  46. GRB 260706A: REM optical/NIR observations
  47. IceCube-260704A: No candidates from the Zwicky Transient Facility
  48. GRB 260706A: LCO optical upper limit
  49. GRB 260706A: EP-FXT follow-up observation
  50. GRB 260707A: Fermi GBM Final Real-time Localization
  51. The EP-WXT trigger 01709274151 is likely a flaring star
  52. The EP-WXT trigger 01709274141 is likely a flaring star
  53. GRB 260706A: Fermi GBM Observation
  54. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  55. IPN triangulation of GRB 260627A
  56. GRB 260705A: SVOM/ECLAIRs refined analysis
  57. GRB 260706A: SVOM detection of a burst
  58. GRB 260706A: Fermi GBM Final Real-time Localization
  59. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  60. The EP-WXT trigger 01709274014 is likely a flaring star
  61. IceCube260704A: OHP/T193 optical observations
  62. GRB 260705A: LCO optical upper limits
  63. GRB 260704A: NOT optical upper limits
  64. GRB 260705C: Fermi GBM Final Localization
  65. GRB 260705B: Fermi GBM Final Real-time Localization
  66. Fermi GBM Sub-Threshold Detection of GRB 260705A
  67. GRB 260705A: SVOM detection of a burst
  68. GRB 260704A: EP-FXT follow-up observation
  69. GRB 260629A: SVOM/GRM observation of a short burst
  70. GRB 260629A: GECAM-A observation of a short burst
  71. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  72. GRB 260629A: AstroSat CZTI detection
  73. EP260703a: EP-FXT follow-up observation
  74. GRB 260704A: SVOM detection of a possible GRB
  75. GRB 260703B: Fermi GBM Final Localization
  76. EP260703a: EP-WXT detection of a fast X-ray transient
  77. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  78. Fermi trigger No 804738310: Global MASTER-Net observations report
  79. Fermi GRB 260703A: Global MASTER-Net observations report
  80. GRB 260703A: Fermi GBM Final Localization
  81. GRB 260610B: VLA detection
  82. GRB 260623A: Glowbug gamma-ray detection
  83. GRB 260614B: ATCA Radio Upper Limits
  84. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  85. Fermi trigger No 804552016: Global MASTER-Net observations report
  86. GRB 260701A: Fermi GBM Final Real-time Localization
  87. Fermi GBM trigger 804552016/260630945 is not a GRB
  88. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  89. EP260628a: EP-FXT follow-up observation
  90. GRB 260629A: Fermi GBM Final Real-time Localization
  91. Fermi GRB 260628A: Global MASTER-Net observations report
  92. EP260628a: EP-WXT detection of a fast X-ray transient
  93. GRB 260628A: Fermi GBM Final Real-time Localization
  94. The EP-WXT trigger 01709272671 is likely a flaring star
  95. EP260626a: further Liverpool Telescope optical upper limits
  96. EP260626a: EP-FXT follow-up observation
  97. EP260626a: COLIBRÍ optical upper limit
  98. EP260626a: Liverpool Telescope upper limits
  99. EP260626a: EP-WXT detection of a fast X-ray transient
  100. Konus-Wind detection of GRB 260623B / EP260623a

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