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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"

42567 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  2. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  3. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 260708A: LCO optical observations
  5. EP260711a: Einstein Probe detection of an X-ray transient
  6. GRB 260710A: Fermi GBM Detection
  7. GRB 260709A: SVOM/GRM detection
  8. GRB 260709A: GECAM-B observation
  9. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  10. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  11. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  12. GRB 260705C: AstroSat CZTI detection
  13. GRB 260710A: Fermi GBM Final Real-time Localization
  14. GRB 260708A: Glowbug gamma-ray detection
  15. GRB 260704A: SVOM/ECLAIRs refined analysis
  16. GRB 260706A : GRANDMA Upper limits
  17. GRB 260708A: Kilonova-Catcher optical afterglow detection
  18. GRB 260708A: GECAM-B observation of a burst
  19. IceCube-260708A: One candidate from the Zwicky Transient Facility
  20. GRB 260708A: Fermi-GBM observation
  21. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  22. IceCube Alert 260709A: Global MASTER-Net observations report
  23. GRB 260709A: Fermi GBM Final Real-time Localization
  24. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  25. LAT GRB260708.42: Global MASTER-Net observations report
  26. GRB260708B: MAXI/GSC detection
  27. GRB 260708A: Fermi-LAT detection
  28. GRB 260705B: SVOM/GRM observation
  29. GRB 260708A: Fermi-GBM detection
  30. GRB 260706A: Further EP-FXT follow-up observation
  31. GRB 260706A: SVOM/VT optical upper limits
  32. EP260707a (by EP-FXT): NOT optical upper limit
  33. EP260707a is not a real source
  34. EP260707a: LCOGT Optical Upper Limit
  35. EP260707a: TRT optical upper limit
  36. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  37. EP260707a: Einstein Probe detection of an X-ray transient
  38. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  39. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  40. GRB 260705C: Glowbug gamma-ray detection of a short burst
  41. GRB 260706A: SVOM/ECLAIRs refined analysis
  42. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  43. GRB 260706A: SVOM/GRM observation
  44. GRB 260706A: REM optical/NIR observations
  45. IceCube-260704A: No candidates from the Zwicky Transient Facility
  46. GRB 260706A: LCO optical upper limit
  47. GRB 260706A: EP-FXT follow-up observation
  48. GRB 260707A: Fermi GBM Final Real-time Localization
  49. The EP-WXT trigger 01709274151 is likely a flaring star
  50. The EP-WXT trigger 01709274141 is likely a flaring star
  51. GRB 260706A: Fermi GBM Observation
  52. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  53. IPN triangulation of GRB 260627A
  54. GRB 260705A: SVOM/ECLAIRs refined analysis
  55. GRB 260706A: SVOM detection of a burst
  56. GRB 260706A: Fermi GBM Final Real-time Localization
  57. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  58. The EP-WXT trigger 01709274014 is likely a flaring star
  59. IceCube260704A: OHP/T193 optical observations
  60. GRB 260705A: LCO optical upper limits
  61. GRB 260704A: NOT optical upper limits
  62. GRB 260705C: Fermi GBM Final Localization
  63. GRB 260705B: Fermi GBM Final Real-time Localization
  64. Fermi GBM Sub-Threshold Detection of GRB 260705A
  65. GRB 260705A: SVOM detection of a burst
  66. GRB 260704A: EP-FXT follow-up observation
  67. GRB 260629A: SVOM/GRM observation of a short burst
  68. GRB 260629A: GECAM-A observation of a short burst
  69. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  70. GRB 260629A: AstroSat CZTI detection
  71. EP260703a: EP-FXT follow-up observation
  72. GRB 260704A: SVOM detection of a possible GRB
  73. GRB 260703B: Fermi GBM Final Localization
  74. EP260703a: EP-WXT detection of a fast X-ray transient
  75. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  76. Fermi trigger No 804738310: Global MASTER-Net observations report
  77. Fermi GRB 260703A: Global MASTER-Net observations report
  78. GRB 260703A: Fermi GBM Final Localization
  79. GRB 260610B: VLA detection
  80. GRB 260623A: Glowbug gamma-ray detection
  81. GRB 260614B: ATCA Radio Upper Limits
  82. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  83. Fermi trigger No 804552016: Global MASTER-Net observations report
  84. GRB 260701A: Fermi GBM Final Real-time Localization
  85. Fermi GBM trigger 804552016/260630945 is not a GRB
  86. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  87. EP260628a: EP-FXT follow-up observation
  88. GRB 260629A: Fermi GBM Final Real-time Localization
  89. Fermi GRB 260628A: Global MASTER-Net observations report
  90. EP260628a: EP-WXT detection of a fast X-ray transient
  91. GRB 260628A: Fermi GBM Final Real-time Localization
  92. The EP-WXT trigger 01709272671 is likely a flaring star
  93. EP260626a: further Liverpool Telescope optical upper limits
  94. EP260626a: EP-FXT follow-up observation
  95. EP260626a: COLIBRÍ optical upper limit
  96. EP260626a: Liverpool Telescope upper limits
  97. EP260626a: EP-WXT detection of a fast X-ray transient
  98. Konus-Wind detection of GRB 260623B / EP260623a
  99. EP260623a: TNG NIR afterglow detection
  100. GRB 260618A: Fermi GBM Observation

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