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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 260710A: AstroSat CZTI detection
  2. GRB 260709A: AstroSat CZTI detection
  3. GRB 260714B: AstroSat CZTI detection
  4. GRB 260714B: Fermi-LAT detection
  5. GRB 260714B: Fermi GBM Detection
  6. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  7. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 260714B: Fermi GBM Final Real-time Localization
  9. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  10. GRB 260706A: ATCA detection of possible radio counterpart
  11. GRB 260705A: ATCA radio observations
  12. GRB 260714A: Fermi GBM Final Real-time Localization
  13. EP260713a: Einstein Probe detection of an X-ray transient
  14. GRB 260619A: SVOM/VT continuous optical observations
  15. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  16. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  17. EP260623a: KAIT optical observations
  18. EP260711a: EP-FXT follow-up observation
  19. GRB 260708A: GRANDMA Optical Observations
  20. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  21. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  22. GRB 260710A: Insight-HXMT/HE detection
  23. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  24. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  25. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  26. GRB 260708A: LCO optical observations
  27. EP260711a: Einstein Probe detection of an X-ray transient
  28. GRB 260710A: Fermi GBM Detection
  29. GRB 260709A: SVOM/GRM detection
  30. GRB 260709A: GECAM-B observation
  31. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  32. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  33. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  34. GRB 260705C: AstroSat CZTI detection
  35. GRB 260710A: Fermi GBM Final Real-time Localization
  36. GRB 260708A: Glowbug gamma-ray detection
  37. GRB 260704A: SVOM/ECLAIRs refined analysis
  38. GRB 260706A : GRANDMA Upper limits
  39. GRB 260708A: Kilonova-Catcher optical afterglow detection
  40. GRB 260708A: GECAM-B observation of a burst
  41. IceCube-260708A: One candidate from the Zwicky Transient Facility
  42. GRB 260708A: Fermi-GBM observation
  43. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  44. IceCube Alert 260709A: Global MASTER-Net observations report
  45. GRB 260709A: Fermi GBM Final Real-time Localization
  46. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  47. LAT GRB260708.42: Global MASTER-Net observations report
  48. GRB260708B: MAXI/GSC detection
  49. GRB 260708A: Fermi-LAT detection
  50. GRB 260705B: SVOM/GRM observation
  51. GRB 260708A: Fermi-GBM detection
  52. GRB 260706A: Further EP-FXT follow-up observation
  53. GRB 260706A: SVOM/VT optical upper limits
  54. EP260707a (by EP-FXT): NOT optical upper limit
  55. EP260707a is not a real source
  56. EP260707a: LCOGT Optical Upper Limit
  57. EP260707a: TRT optical upper limit
  58. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  59. EP260707a: Einstein Probe detection of an X-ray transient
  60. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  61. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  62. GRB 260705C: Glowbug gamma-ray detection of a short burst
  63. GRB 260706A: SVOM/ECLAIRs refined analysis
  64. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  65. GRB 260706A: SVOM/GRM observation
  66. GRB 260706A: REM optical/NIR observations
  67. IceCube-260704A: No candidates from the Zwicky Transient Facility
  68. GRB 260706A: LCO optical upper limit
  69. GRB 260706A: EP-FXT follow-up observation
  70. GRB 260707A: Fermi GBM Final Real-time Localization
  71. The EP-WXT trigger 01709274151 is likely a flaring star
  72. The EP-WXT trigger 01709274141 is likely a flaring star
  73. GRB 260706A: Fermi GBM Observation
  74. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  75. IPN triangulation of GRB 260627A
  76. GRB 260705A: SVOM/ECLAIRs refined analysis
  77. GRB 260706A: SVOM detection of a burst
  78. GRB 260706A: Fermi GBM Final Real-time Localization
  79. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  80. The EP-WXT trigger 01709274014 is likely a flaring star
  81. IceCube260704A: OHP/T193 optical observations
  82. GRB 260705A: LCO optical upper limits
  83. GRB 260704A: NOT optical upper limits
  84. GRB 260705C: Fermi GBM Final Localization
  85. GRB 260705B: Fermi GBM Final Real-time Localization
  86. Fermi GBM Sub-Threshold Detection of GRB 260705A
  87. GRB 260705A: SVOM detection of a burst
  88. GRB 260704A: EP-FXT follow-up observation
  89. GRB 260629A: SVOM/GRM observation of a short burst
  90. GRB 260629A: GECAM-A observation of a short burst
  91. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  92. GRB 260629A: AstroSat CZTI detection
  93. EP260703a: EP-FXT follow-up observation
  94. GRB 260704A: SVOM detection of a possible GRB
  95. GRB 260703B: Fermi GBM Final Localization
  96. EP260703a: EP-WXT detection of a fast X-ray transient
  97. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  98. Fermi trigger No 804738310: Global MASTER-Net observations report
  99. Fermi GRB 260703A: Global MASTER-Net observations report
  100. GRB 260703A: Fermi GBM Final Localization

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