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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"

32514 results found.

  1. GRB 260708A: Kilonova-Catcher optical afterglow detection
  2. GRB 260708A: GECAM-B observation of a burst
  3. IceCube-260708A: One candidate from the Zwicky Transient Facility
  4. GRB 260708A: Fermi-GBM observation
  5. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  6. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  7. GRB 260708A: Fermi-LAT detection
  8. GRB 260705B: SVOM/GRM observation
  9. GRB 260706A: Further EP-FXT follow-up observation
  10. GRB 260706A: SVOM/VT optical upper limits
  11. EP260707a (by EP-FXT): NOT optical upper limit
  12. EP260707a is not a real source
  13. EP260707a: LCOGT Optical Upper Limit
  14. EP260707a: TRT optical upper limit
  15. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  16. GRB 260705C: Glowbug gamma-ray detection of a short burst
  17. GRB 260706A: SVOM/ECLAIRs refined analysis
  18. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  19. GRB 260706A: SVOM/GRM observation
  20. GRB 260706A: REM optical/NIR observations
  21. IceCube-260704A: No candidates from the Zwicky Transient Facility
  22. GRB 260706A: LCO optical upper limit
  23. GRB 260706A: EP-FXT follow-up observation
  24. GRB 260706A: Fermi GBM Observation
  25. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  26. IPN triangulation of GRB 260627A
  27. GRB 260705A: SVOM/ECLAIRs refined analysis
  28. GRB 260706A: SVOM detection of a burst
  29. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  30. IceCube260704A: OHP/T193 optical observations
  31. GRB 260705A: LCO optical upper limits
  32. GRB 260704A: NOT optical upper limits
  33. Fermi GBM Sub-Threshold Detection of GRB 260705A
  34. GRB 260704A: EP-FXT follow-up observation
  35. GRB 260629A: SVOM/GRM observation of a short burst
  36. GRB 260629A: GECAM-A observation of a short burst
  37. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  38. GRB 260629A: AstroSat CZTI detection
  39. EP260703a: EP-FXT follow-up observation
  40. Fermi GRB 260703A: Global MASTER-Net observations report
  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-LAT Gamma-ray Observations of IceCube-260622A
  46. EP260628a: EP-FXT follow-up observation
  47. Fermi GRB 260628A: Global MASTER-Net observations report
  48. EP260626a: further Liverpool Telescope optical upper limits
  49. EP260626a: EP-FXT follow-up observation
  50. EP260626a: COLIBRÍ optical upper limit
  51. EP260626a: Liverpool Telescope upper limits
  52. Konus-Wind detection of GRB 260623B / EP260623a
  53. EP260623a: TNG NIR afterglow detection
  54. GRB 260618A: Fermi GBM Observation
  55. MASS-Cube (GRID 2.0) detection of GRB 260616B
  56. EP260623a: FTW optical and NIR observations
  57. GRB 260619A: SVOM/ECLAIRs refined analysis
  58. EP260623a: Liverpool Telescope optical observations
  59. Konus-Wind detection of GRB 260618B
  60. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  61. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  62. EP260623a: WINTER J-band observations
  63. GRB 260617A: Glowbug gamma-ray detection of a short burst
  64. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  65. IPN triangulation of GRB 260605A
  66. EP260623a: Optical follow-up observations with Kinder
  67. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  68. EP260623a: SVOM/VT optical observations
  69. EP260623a: TRT optical observations
  70. EP260623a: REM optical/NIR afterglow detection
  71. EP 260623a: COLIBRÍ optical observations
  72. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  73. EP260623a: OSIRIS+/GTC redshift z = 0.703
  74. EP260623a: Las Cumbres discovery of the optical counterpart
  75. GRB 260614B: EP-FXT follow-up observation
  76. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  77. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  78. EP260618a: Liverpool Telescope optical observations
  79. GRB 260619A: NOT optical observations
  80. GRB 260618B: LCO optical observations
  81. EP260618a: JinShan optical observations
  82. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  83. GRB 260618B: Fermi GBM Observation
  84. GRB 260619A: TRT optical counterpart confirmation
  85. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  86. GRB 260604B: 239Alferov CubeSat detection
  87. GRB 260604A: 239Alferov CubeSat detection
  88. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  89. GRB 260619A: SVOM/VT optical counterpart confirmation
  90. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  91. GRB 260618B: SVOM/VT optical candidate
  92. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  93. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  94. Konus-Wind detection of GRB 260617A
  95. GRB 260616B: AstroSat CZTI detection
  96. GRB 260616A: AstroSat CZTI detection
  97. GRB 260616A: SVOM/GRM observation
  98. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  99. GRB 260619A: Kilonova-Catcher optical upper limit
  100. EP260618a: EP-FXT follow-up observation

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