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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"

41622 results found.

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

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