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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"

45352 results found.

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

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