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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"

45439 results found.

  1. GRB 260714B: Fermi-LAT detection
  2. GRB 260714B: Fermi GBM Detection
  3. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  4. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  5. GRB 260714B: Fermi GBM Final Real-time Localization
  6. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  7. GRB 260706A: ATCA detection of possible radio counterpart
  8. GRB 260705A: ATCA radio observations
  9. GRB 260714A: Fermi GBM Final Real-time Localization
  10. EP260713a: Einstein Probe detection of an X-ray transient
  11. GRB 260619A: SVOM/VT continuous optical observations
  12. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  13. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  14. EP260623a: KAIT optical observations
  15. EP260711a: EP-FXT follow-up observation
  16. GRB 260708A: GRANDMA Optical Observations
  17. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  18. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  19. GRB 260710A: Insight-HXMT/HE detection
  20. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  21. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  22. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  23. GRB 260708A: LCO optical observations
  24. EP260711a: Einstein Probe detection of an X-ray transient
  25. GRB 260710A: Fermi GBM Detection
  26. GRB 260709A: SVOM/GRM detection
  27. GRB 260709A: GECAM-B observation
  28. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  29. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  30. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  31. GRB 260705C: AstroSat CZTI detection
  32. GRB 260710A: Fermi GBM Final Real-time Localization
  33. GRB 260708A: Glowbug gamma-ray detection
  34. GRB 260704A: SVOM/ECLAIRs refined analysis
  35. GRB 260706A : GRANDMA Upper limits
  36. GRB 260708A: Kilonova-Catcher optical afterglow detection
  37. GRB 260708A: GECAM-B observation of a burst
  38. IceCube-260708A: One candidate from the Zwicky Transient Facility
  39. GRB 260708A: Fermi-GBM observation
  40. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  41. IceCube Alert 260709A: Global MASTER-Net observations report
  42. GRB 260709A: Fermi GBM Final Real-time Localization
  43. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  44. LAT GRB260708.42: Global MASTER-Net observations report
  45. GRB260708B: MAXI/GSC detection
  46. GRB 260708A: Fermi-LAT detection
  47. GRB 260705B: SVOM/GRM observation
  48. GRB 260708A: Fermi-GBM detection
  49. GRB 260706A: Further EP-FXT follow-up observation
  50. GRB 260706A: SVOM/VT optical upper limits
  51. EP260707a (by EP-FXT): NOT optical upper limit
  52. EP260707a is not a real source
  53. EP260707a: LCOGT Optical Upper Limit
  54. EP260707a: TRT optical upper limit
  55. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  56. EP260707a: Einstein Probe detection of an X-ray transient
  57. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  58. GRB 260705C: Glowbug gamma-ray detection of a short burst
  59. GRB 260706A: SVOM/ECLAIRs refined analysis
  60. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  61. GRB 260706A: SVOM/GRM observation
  62. GRB 260706A: REM optical/NIR observations
  63. IceCube-260704A: No candidates from the Zwicky Transient Facility
  64. GRB 260706A: LCO optical upper limit
  65. GRB 260706A: EP-FXT follow-up observation
  66. GRB 260707A: Fermi GBM Final Real-time Localization
  67. The EP-WXT trigger 01709274151 is likely a flaring star
  68. The EP-WXT trigger 01709274141 is likely a flaring star
  69. GRB 260706A: Fermi GBM Observation
  70. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  71. IPN triangulation of GRB 260627A
  72. GRB 260705A: SVOM/ECLAIRs refined analysis
  73. GRB 260706A: SVOM detection of a burst
  74. GRB 260706A: Fermi GBM Final Real-time Localization
  75. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  76. The EP-WXT trigger 01709274014 is likely a flaring star
  77. IceCube260704A: OHP/T193 optical observations
  78. GRB 260705A: LCO optical upper limits
  79. GRB 260704A: NOT optical upper limits
  80. GRB 260705C: Fermi GBM Final Localization
  81. GRB 260705B: Fermi GBM Final Real-time Localization
  82. Fermi GBM Sub-Threshold Detection of GRB 260705A
  83. GRB 260705A: SVOM detection of a burst
  84. GRB 260704A: EP-FXT follow-up observation
  85. GRB 260629A: SVOM/GRM observation of a short burst
  86. GRB 260629A: GECAM-A observation of a short burst
  87. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  88. GRB 260629A: AstroSat CZTI detection
  89. EP260703a: EP-FXT follow-up observation
  90. GRB 260704A: SVOM detection of a possible GRB
  91. GRB 260703B: Fermi GBM Final Localization
  92. EP260703a: EP-WXT detection of a fast X-ray transient
  93. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  94. Fermi trigger No 804738310: Global MASTER-Net observations report
  95. Fermi GRB 260703A: Global MASTER-Net observations report
  96. GRB 260703A: Fermi GBM Final Localization
  97. GRB 260610B: VLA detection
  98. GRB 260623A: Glowbug gamma-ray detection
  99. GRB 260614B: ATCA Radio Upper Limits
  100. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve

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