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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"

27392 results found.

  1. GRB 260704A: SVOM/ECLAIRs refined analysis
  2. GRB 260708A: Fermi-GBM observation
  3. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  4. IceCube Alert 260709A: Global MASTER-Net observations report
  5. GRB 260709A: Fermi GBM Final Real-time Localization
  6. LAT GRB260708.42: Global MASTER-Net observations report
  7. GRB 260708A: Fermi-LAT detection
  8. GRB 260708A: Fermi-GBM detection
  9. GRB 260706A: Further EP-FXT follow-up observation
  10. GRB 260706A: SVOM/VT optical upper limits
  11. EP260707a: LCOGT Optical Upper Limit
  12. EP260707a: TRT optical upper limit
  13. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  14. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  15. GRB 260706A: SVOM/ECLAIRs refined analysis
  16. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  17. GRB 260706A: REM optical/NIR observations
  18. GRB 260706A: LCO optical upper limit
  19. GRB 260706A: EP-FXT follow-up observation
  20. GRB 260707A: Fermi GBM Final Real-time Localization
  21. The EP-WXT trigger 01709274151 is likely a flaring star
  22. The EP-WXT trigger 01709274141 is likely a flaring star
  23. GRB 260706A: Fermi GBM Observation
  24. GRB 260706A: SVOM detection of a burst
  25. GRB 260706A: Fermi GBM Final Real-time Localization
  26. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  27. The EP-WXT trigger 01709274014 is likely a flaring star
  28. IceCube260704A: OHP/T193 optical observations
  29. GRB 260705A: LCO optical upper limits
  30. GRB 260704A: NOT optical upper limits
  31. GRB 260705C: Fermi GBM Final Localization
  32. GRB 260705B: Fermi GBM Final Real-time Localization
  33. Fermi GBM Sub-Threshold Detection of GRB 260705A
  34. GRB 260705A: SVOM detection of a burst
  35. GRB 260704A: EP-FXT follow-up observation
  36. GRB 260704A: SVOM detection of a possible GRB
  37. GRB 260703B: Fermi GBM Final Localization
  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 / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  42. Fermi trigger No 804552016: Global MASTER-Net observations report
  43. GRB 260701A: Fermi GBM Final Real-time Localization
  44. Fermi GBM trigger 804552016/260630945 is not a GRB
  45. GRB 260629A: Fermi GBM Final Real-time Localization
  46. Fermi GRB 260628A: Global MASTER-Net observations report
  47. GRB 260628A: Fermi GBM Final Real-time Localization
  48. The EP-WXT trigger 01709272671 is likely a flaring star
  49. EP260626a: further Liverpool Telescope optical upper limits
  50. EP260626a: COLIBRÍ optical upper limit
  51. EP260623a: TNG NIR afterglow detection
  52. GRB 260618A: Fermi GBM Observation
  53. EP260623a: FTW optical and NIR observations
  54. EP260623a: Liverpool Telescope optical observations
  55. Fermi GBM trigger 804010507/260624677 is not a GRB
  56. GRB 260624A: Fermi GBM Final Real-time Localization
  57. EP260623a: WINTER J-band observations
  58. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  59. GRB 260623A: Fermi GBM Final Real-time Localization
  60. EP260623a: SVOM/VT optical observations
  61. EP260623a: TRT optical observations
  62. EP260623a: REM optical/NIR afterglow detection
  63. EP 260623a: COLIBRÍ optical observations
  64. EP260623a: OSIRIS+/GTC redshift z = 0.703
  65. EP260623a: Las Cumbres discovery of the optical counterpart
  66. GRB 260614B: EP-FXT follow-up observation
  67. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  68. EP260618a: Liverpool Telescope optical observations
  69. GRB 260619A: NOT optical observations
  70. GRB 260618B: LCO optical observations
  71. The EP-WXT trigger 01709271197 is likely a flaring star
  72. EP260618a: JinShan optical observations
  73. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  74. GRB 260618B: Fermi GBM Observation
  75. GRB 260619A: TRT optical counterpart confirmation
  76. GRB 260619A: SVOM/VT optical counterpart confirmation
  77. GRB 260618B: SVOM/VT optical candidate
  78. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  79. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  80. Konus-Wind detection of GRB 260617A
  81. EP260618a: OHP/T193 optical observations
  82. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  83. EP260618a: LCO optical counterpart confirmation
  84. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  85. EP260618a: COLIBRÍ optical counterpart candidate
  86. GRB 260619A: SVOM possible detection of a faint burst
  87. GRB 260618B: Fermi-LAT detection
  88. IPN triangulation of GRB 260617A (short)
  89. GRB 260618B: Fermi GBM Final Real-time Localization
  90. GRB 260610B: AbAO optical observations
  91. GRB 260618A: Fermi GBM Final Real-time Localization
  92. GRB 260617A: Fermi GBM Detection
  93. GRB 260616A: Fermi GBM Observation
  94. GRB 260617A: Fermi GBM Final Real-time Localization
  95. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  96. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  97. GRB 260616A: Fermi-LAT detection
  98. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  99. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  100. The EP-WXT trigger 01709270148 is likely a flaring star

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