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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"

42611 results found.

  1. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  2. GRB 260705C: Glowbug gamma-ray detection of a short burst
  3. GRB 260706A: SVOM/ECLAIRs refined analysis
  4. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  5. GRB 260706A: SVOM/GRM observation
  6. GRB 260706A: REM optical/NIR observations
  7. IceCube-260704A: No candidates from the Zwicky Transient Facility
  8. GRB 260706A: LCO optical upper limit
  9. GRB 260706A: EP-FXT follow-up observation
  10. GRB 260707A: Fermi GBM Final Real-time Localization
  11. The EP-WXT trigger 01709274151 is likely a flaring star
  12. The EP-WXT trigger 01709274141 is likely a flaring star
  13. GRB 260706A: Fermi GBM Observation
  14. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  15. IPN triangulation of GRB 260627A
  16. GRB 260705A: SVOM/ECLAIRs refined analysis
  17. GRB 260706A: SVOM detection of a burst
  18. GRB 260706A: Fermi GBM Final Real-time Localization
  19. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  20. The EP-WXT trigger 01709274014 is likely a flaring star
  21. IceCube260704A: OHP/T193 optical observations
  22. GRB 260705A: LCO optical upper limits
  23. GRB 260704A: NOT optical upper limits
  24. GRB 260705C: Fermi GBM Final Localization
  25. GRB 260705B: Fermi GBM Final Real-time Localization
  26. Fermi GBM Sub-Threshold Detection of GRB 260705A
  27. GRB 260705A: SVOM detection of a burst
  28. GRB 260704A: EP-FXT follow-up observation
  29. GRB 260629A: SVOM/GRM observation of a short burst
  30. GRB 260629A: GECAM-A observation of a short burst
  31. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 260629A: AstroSat CZTI detection
  33. EP260703a: EP-FXT follow-up observation
  34. GRB 260704A: SVOM detection of a possible GRB
  35. GRB 260703B: Fermi GBM Final Localization
  36. EP260703a: EP-WXT detection of a fast X-ray transient
  37. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  38. Fermi trigger No 804738310: Global MASTER-Net observations report
  39. Fermi GRB 260703A: Global MASTER-Net observations report
  40. GRB 260703A: Fermi GBM Final Localization
  41. GRB 260610B: VLA detection
  42. GRB 260623A: Glowbug gamma-ray detection
  43. GRB 260614B: ATCA Radio Upper Limits
  44. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  45. Fermi trigger No 804552016: Global MASTER-Net observations report
  46. GRB 260701A: Fermi GBM Final Real-time Localization
  47. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  48. EP260628a: EP-FXT follow-up observation
  49. GRB 260629A: Fermi GBM Final Real-time Localization
  50. Fermi GRB 260628A: Global MASTER-Net observations report
  51. EP260628a: EP-WXT detection of a fast X-ray transient
  52. GRB 260628A: Fermi GBM Final Real-time Localization
  53. The EP-WXT trigger 01709272671 is likely a flaring star
  54. EP260626a: further Liverpool Telescope optical upper limits
  55. EP260626a: EP-FXT follow-up observation
  56. EP260626a: COLIBRÍ optical upper limit
  57. EP260626a: Liverpool Telescope upper limits
  58. EP260626a: EP-WXT detection of a fast X-ray transient
  59. Konus-Wind detection of GRB 260623B / EP260623a
  60. EP260623a: TNG NIR afterglow detection
  61. GRB 260618A: Fermi GBM Observation
  62. MASS-Cube (GRID 2.0) detection of GRB 260616B
  63. EP260623a: FTW optical and NIR observations
  64. GRB 260619A: SVOM/ECLAIRs refined analysis
  65. EP260623a: Liverpool Telescope optical observations
  66. Konus-Wind detection of GRB 260618B
  67. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  68. GRB 260624A: Fermi GBM Final Real-time Localization
  69. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  70. EP260623a: WINTER J-band observations
  71. GRB 260617A: Glowbug gamma-ray detection of a short burst
  72. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  73. IPN triangulation of GRB 260605A
  74. EP260623a: Optical follow-up observations with Kinder
  75. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  76. GRB 260623A: Fermi GBM Final Real-time Localization
  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: OSIRIS+/GTC redshift z = 0.703
  83. EP260623a: Las Cumbres discovery of the optical counterpart
  84. EP260623a: Einstein Probe detection of an X-ray transient
  85. GRB 260614B: EP-FXT follow-up observation
  86. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  87. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  88. EP260618a: Liverpool Telescope optical observations
  89. GRB 260619A: NOT optical observations
  90. GRB 260618B: LCO optical observations
  91. The EP-WXT trigger 01709271197 is likely a flaring star
  92. EP260618a: JinShan optical observations
  93. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  94. GRB 260618B: Fermi GBM Observation
  95. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  96. GRB 260619A: TRT optical counterpart confirmation
  97. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  98. GRB 260604B: 239Alferov CubeSat detection
  99. GRB 260604A: 239Alferov CubeSat detection
  100. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening

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