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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"

28035 results found.

  1. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  2. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  3. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  4. EP260713a: Einstein Probe detection of an X-ray transient
  5. GRB 260619A: SVOM/VT continuous optical observations
  6. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  7. EP260623a: KAIT optical observations
  8. GRB 260708A: GRANDMA Optical Observations
  9. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  10. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  11. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  12. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 260708A: LCO optical observations
  14. EP260711a: Einstein Probe detection of an X-ray transient
  15. GRB 260709A: SVOM/GRM detection
  16. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  17. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  18. GRB 260708A: Glowbug gamma-ray detection
  19. GRB 260706A : GRANDMA Upper limits
  20. GRB 260708A: Kilonova-Catcher optical afterglow detection
  21. IceCube-260708A: One candidate from the Zwicky Transient Facility
  22. GRB 260708A: Fermi-GBM observation
  23. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  24. IceCube Alert 260709A: Global MASTER-Net observations report
  25. LAT GRB260708.42: Global MASTER-Net observations report
  26. GRB260708B: MAXI/GSC detection
  27. GRB 260705B: SVOM/GRM observation
  28. GRB 260706A: Further EP-FXT follow-up observation
  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. EP260707a: Einstein Probe detection of an X-ray transient
  34. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  35. GRB 260705C: Glowbug gamma-ray detection of a short burst
  36. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  37. GRB 260706A: REM optical/NIR observations
  38. GRB 260706A: LCO optical upper limit
  39. GRB 260706A: EP-FXT follow-up observation
  40. The EP-WXT trigger 01709274151 is likely a flaring star
  41. GRB 260706A: Fermi GBM Observation
  42. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 260706A: SVOM detection of a burst
  44. GRB 260705A: LCO optical upper limits
  45. GRB 260704A: NOT optical upper limits
  46. Fermi GBM Sub-Threshold Detection of GRB 260705A
  47. GRB 260704A: EP-FXT follow-up observation
  48. GRB 260629A: SVOM/GRM observation of a short burst
  49. GRB 260629A: AstroSat CZTI detection
  50. EP260703a: EP-FXT follow-up observation
  51. GRB 260704A: SVOM detection of a possible GRB
  52. EP260703a: EP-WXT detection of a fast X-ray transient
  53. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  54. Fermi trigger No 804738310: Global MASTER-Net observations report
  55. Fermi GRB 260703A: Global MASTER-Net observations report
  56. GRB 260623A: Glowbug gamma-ray detection
  57. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  58. Fermi trigger No 804552016: Global MASTER-Net observations report
  59. GRB 260701A: Fermi GBM Final Real-time Localization
  60. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  61. EP260628a: EP-FXT follow-up observation
  62. Fermi GRB 260628A: Global MASTER-Net observations report
  63. EP260628a: EP-WXT detection of a fast X-ray transient
  64. EP260626a: further Liverpool Telescope optical upper limits
  65. EP260626a: COLIBRÍ optical upper limit
  66. EP260626a: Liverpool Telescope upper limits
  67. EP260626a: EP-WXT detection of a fast X-ray transient
  68. EP260623a: TNG NIR afterglow detection
  69. GRB 260618A: Fermi GBM Observation
  70. GRB 260619A: SVOM/ECLAIRs refined analysis
  71. EP260623a: Liverpool Telescope optical observations
  72. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  73. EP260623a: WINTER J-band observations
  74. GRB 260617A: Glowbug gamma-ray detection of a short burst
  75. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  76. EP260623a: Optical follow-up observations with Kinder
  77. EP260623a: SVOM/VT optical observations
  78. EP260623a: TRT optical observations
  79. EP260623a: REM optical/NIR afterglow detection
  80. EP 260623a: COLIBRÍ optical observations
  81. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  82. EP260623a: Las Cumbres discovery of the optical counterpart
  83. EP260623a: Einstein Probe detection of an X-ray transient
  84. GRB 260614B: EP-FXT follow-up observation
  85. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  86. EP260618a: Liverpool Telescope optical observations
  87. GRB 260618B: LCO optical observations
  88. EP260618a: JinShan optical observations
  89. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  90. GRB 260618B: Fermi GBM Observation
  91. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  92. GRB 260619A: TRT optical counterpart confirmation
  93. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  94. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  95. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  96. GRB 260616B: AstroSat CZTI detection
  97. GRB 260616A: AstroSat CZTI detection
  98. GRB 260616A: SVOM/GRM observation
  99. EP260618a: OHP/T193 optical observations
  100. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection

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