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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"

42564 results found.

  1. GRB 260708A: LCO optical observations
  2. EP260711a: Einstein Probe detection of an X-ray transient
  3. GRB 260710A: Fermi GBM Detection
  4. GRB 260709A: SVOM/GRM detection
  5. GRB 260709A: GECAM-B observation
  6. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  7. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  8. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  9. GRB 260705C: AstroSat CZTI detection
  10. GRB 260710A: Fermi GBM Final Real-time Localization
  11. GRB 260708A: Glowbug gamma-ray detection
  12. GRB 260704A: SVOM/ECLAIRs refined analysis
  13. GRB 260706A : GRANDMA Upper limits
  14. GRB 260708A: Kilonova-Catcher optical afterglow detection
  15. GRB 260708A: GECAM-B observation of a burst
  16. IceCube-260708A: One candidate from the Zwicky Transient Facility
  17. GRB 260708A: Fermi-GBM observation
  18. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  19. IceCube Alert 260709A: Global MASTER-Net observations report
  20. GRB 260709A: Fermi GBM Final Real-time Localization
  21. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  22. LAT GRB260708.42: Global MASTER-Net observations report
  23. GRB260708B: MAXI/GSC detection
  24. GRB 260708A: Fermi-LAT detection
  25. GRB 260705B: SVOM/GRM observation
  26. GRB 260708A: Fermi-GBM detection
  27. GRB 260706A: Further EP-FXT follow-up observation
  28. GRB 260706A: SVOM/VT optical upper limits
  29. EP260707a (by EP-FXT): NOT optical upper limit
  30. EP260707a is not a real source
  31. EP260707a: LCOGT Optical Upper Limit
  32. EP260707a: TRT optical upper limit
  33. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  34. EP260707a: Einstein Probe detection of an X-ray transient
  35. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  36. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  37. GRB 260705C: Glowbug gamma-ray detection of a short burst
  38. GRB 260706A: SVOM/ECLAIRs refined analysis
  39. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  40. GRB 260706A: SVOM/GRM observation
  41. GRB 260706A: REM optical/NIR observations
  42. IceCube-260704A: No candidates from the Zwicky Transient Facility
  43. GRB 260706A: LCO optical upper limit
  44. GRB 260706A: EP-FXT follow-up observation
  45. GRB 260707A: Fermi GBM Final Real-time Localization
  46. The EP-WXT trigger 01709274151 is likely a flaring star
  47. The EP-WXT trigger 01709274141 is likely a flaring star
  48. GRB 260706A: Fermi GBM Observation
  49. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  50. IPN triangulation of GRB 260627A
  51. GRB 260705A: SVOM/ECLAIRs refined analysis
  52. GRB 260706A: SVOM detection of a burst
  53. GRB 260706A: Fermi GBM Final Real-time Localization
  54. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  55. The EP-WXT trigger 01709274014 is likely a flaring star
  56. IceCube260704A: OHP/T193 optical observations
  57. GRB 260705A: LCO optical upper limits
  58. GRB 260704A: NOT optical upper limits
  59. GRB 260705C: Fermi GBM Final Localization
  60. GRB 260705B: Fermi GBM Final Real-time Localization
  61. Fermi GBM Sub-Threshold Detection of GRB 260705A
  62. GRB 260705A: SVOM detection of a burst
  63. GRB 260704A: EP-FXT follow-up observation
  64. GRB 260629A: SVOM/GRM observation of a short burst
  65. GRB 260629A: GECAM-A observation of a short burst
  66. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 260629A: AstroSat CZTI detection
  68. EP260703a: EP-FXT follow-up observation
  69. GRB 260704A: SVOM detection of a possible GRB
  70. GRB 260703B: Fermi GBM Final Localization
  71. EP260703a: EP-WXT detection of a fast X-ray transient
  72. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  73. Fermi trigger No 804738310: Global MASTER-Net observations report
  74. Fermi GRB 260703A: Global MASTER-Net observations report
  75. GRB 260703A: Fermi GBM Final Localization
  76. GRB 260610B: VLA detection
  77. GRB 260623A: Glowbug gamma-ray detection
  78. GRB 260614B: ATCA Radio Upper Limits
  79. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  80. Fermi trigger No 804552016: Global MASTER-Net observations report
  81. GRB 260701A: Fermi GBM Final Real-time Localization
  82. Fermi GBM trigger 804552016/260630945 is not a GRB
  83. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  84. EP260628a: EP-FXT follow-up observation
  85. GRB 260629A: Fermi GBM Final Real-time Localization
  86. Fermi GRB 260628A: Global MASTER-Net observations report
  87. EP260628a: EP-WXT detection of a fast X-ray transient
  88. GRB 260628A: Fermi GBM Final Real-time Localization
  89. The EP-WXT trigger 01709272671 is likely a flaring star
  90. EP260626a: further Liverpool Telescope optical upper limits
  91. EP260626a: EP-FXT follow-up observation
  92. EP260626a: COLIBRÍ optical upper limit
  93. EP260626a: Liverpool Telescope upper limits
  94. EP260626a: EP-WXT detection of a fast X-ray transient
  95. Konus-Wind detection of GRB 260623B / EP260623a
  96. EP260623a: TNG NIR afterglow detection
  97. GRB 260618A: Fermi GBM Observation
  98. MASS-Cube (GRID 2.0) detection of GRB 260616B
  99. GRB 260619A: SVOM/ECLAIRs refined analysis
  100. EP260623a: Liverpool Telescope optical observations

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