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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"

28870 results found.

  1. GRB 260706A: Further EP-FXT follow-up observation
  2. GRB 260706A: SVOM/VT optical upper limits
  3. EP260707a: LCOGT Optical Upper Limit
  4. EP260707a: TRT optical upper limit
  5. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  6. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  7. GRB 260705C: Glowbug gamma-ray detection of a short burst
  8. GRB 260706A: SVOM/ECLAIRs refined analysis
  9. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  10. GRB 260706A: SVOM/GRM observation
  11. GRB 260706A: REM optical/NIR observations
  12. GRB 260706A: LCO optical upper limit
  13. GRB 260706A: EP-FXT follow-up observation
  14. GRB 260707A: Fermi GBM Final Real-time Localization
  15. The EP-WXT trigger 01709274151 is likely a flaring star
  16. The EP-WXT trigger 01709274141 is likely a flaring star
  17. GRB 260706A: Fermi GBM Observation
  18. GRB 260706A: SVOM detection of a burst
  19. GRB 260706A: Fermi GBM Final Real-time Localization
  20. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  21. The EP-WXT trigger 01709274014 is likely a flaring star
  22. IceCube260704A: OHP/T193 optical observations
  23. GRB 260705A: LCO optical upper limits
  24. GRB 260704A: NOT optical upper limits
  25. GRB 260705C: Fermi GBM Final Localization
  26. GRB 260705B: Fermi GBM Final Real-time Localization
  27. Fermi GBM Sub-Threshold Detection of GRB 260705A
  28. GRB 260705A: SVOM detection of a burst
  29. GRB 260704A: EP-FXT follow-up observation
  30. GRB 260629A: SVOM/GRM observation of a short burst
  31. GRB 260629A: GECAM-A observation of a short burst
  32. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  33. GRB 260629A: AstroSat CZTI detection
  34. GRB 260704A: SVOM detection of a possible GRB
  35. GRB 260703B: Fermi GBM Final Localization
  36. Fermi trigger No 804738310: Global MASTER-Net observations report
  37. Fermi GRB 260703A: Global MASTER-Net observations report
  38. GRB 260703A: Fermi GBM Final Localization
  39. GRB 260610B: VLA detection
  40. GRB 260623A: Glowbug gamma-ray detection
  41. GRB 260614B: ATCA Radio Upper Limits
  42. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  43. Fermi trigger No 804552016: Global MASTER-Net observations report
  44. GRB 260701A: Fermi GBM Final Real-time Localization
  45. Fermi GBM trigger 804552016/260630945 is not a GRB
  46. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  47. GRB 260629A: Fermi GBM Final Real-time Localization
  48. Fermi GRB 260628A: Global MASTER-Net observations report
  49. GRB 260628A: Fermi GBM Final Real-time Localization
  50. The EP-WXT trigger 01709272671 is likely a flaring star
  51. EP260626a: further Liverpool Telescope optical upper limits
  52. EP260626a: COLIBRÍ optical upper limit
  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. EP260623a: Liverpool Telescope optical observations
  58. Fermi GBM trigger 804010507/260624677 is not a GRB
  59. Konus-Wind detection of GRB 260618B
  60. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  61. GRB 260624A: Fermi GBM Final Real-time Localization
  62. EP260623a: WINTER J-band observations
  63. GRB 260617A: Glowbug gamma-ray detection of a short burst
  64. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  65. GRB 260623A: Fermi GBM Final Real-time Localization
  66. EP260623a: SVOM/VT optical observations
  67. EP260623a: TRT optical observations
  68. EP260623a: REM optical/NIR afterglow detection
  69. EP 260623a: COLIBRÍ optical observations
  70. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  71. EP260623a: OSIRIS+/GTC redshift z = 0.703
  72. EP260623a: Las Cumbres discovery of the optical counterpart
  73. GRB 260614B: EP-FXT follow-up observation
  74. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  76. EP260618a: Liverpool Telescope optical observations
  77. GRB 260619A: NOT optical observations
  78. GRB 260618B: LCO optical observations
  79. The EP-WXT trigger 01709271197 is likely a flaring star
  80. EP260618a: JinShan optical observations
  81. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  82. GRB 260618B: Fermi GBM Observation
  83. GRB 260619A: TRT optical counterpart confirmation
  84. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  85. GRB 260604B: 239Alferov CubeSat detection
  86. GRB 260604A: 239Alferov CubeSat detection
  87. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  88. GRB 260619A: SVOM/VT optical counterpart confirmation
  89. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  90. GRB 260618B: SVOM/VT optical candidate
  91. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  92. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  93. Konus-Wind detection of GRB 260617A
  94. GRB 260616B: AstroSat CZTI detection
  95. GRB 260616A: AstroSat CZTI detection
  96. GRB 260616A: SVOM/GRM observation
  97. EP260618a: OHP/T193 optical observations
  98. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  99. EP260618a: EP-FXT follow-up observation
  100. EP260618a: LCO optical counterpart confirmation

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