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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"

27400 results found.

  1. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  2. GRB 260708A: GRANDMA Optical Observations
  3. GRB 260708A: LCO optical observations
  4. GRB 260710A: Fermi GBM Detection
  5. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  6. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  7. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  8. GRB 260710A: Fermi GBM Final Real-time Localization
  9. GRB 260704A: SVOM/ECLAIRs refined analysis
  10. GRB 260708A: Fermi-GBM observation
  11. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  12. IceCube Alert 260709A: Global MASTER-Net observations report
  13. GRB 260709A: Fermi GBM Final Real-time Localization
  14. LAT GRB260708.42: Global MASTER-Net observations report
  15. GRB 260708A: Fermi-LAT detection
  16. GRB 260708A: Fermi-GBM detection
  17. GRB 260706A: Further EP-FXT follow-up observation
  18. GRB 260706A: SVOM/VT optical upper limits
  19. EP260707a: LCOGT Optical Upper Limit
  20. EP260707a: TRT optical upper limit
  21. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  22. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  23. GRB 260706A: SVOM/ECLAIRs refined analysis
  24. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  25. GRB 260706A: REM optical/NIR observations
  26. GRB 260706A: LCO optical upper limit
  27. GRB 260706A: EP-FXT follow-up observation
  28. GRB 260707A: Fermi GBM Final Real-time Localization
  29. The EP-WXT trigger 01709274151 is likely a flaring star
  30. The EP-WXT trigger 01709274141 is likely a flaring star
  31. GRB 260706A: Fermi GBM Observation
  32. GRB 260706A: SVOM detection of a burst
  33. GRB 260706A: Fermi GBM Final Real-time Localization
  34. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  35. The EP-WXT trigger 01709274014 is likely a flaring star
  36. IceCube260704A: OHP/T193 optical observations
  37. GRB 260705A: LCO optical upper limits
  38. GRB 260704A: NOT optical upper limits
  39. GRB 260705C: Fermi GBM Final Localization
  40. GRB 260705B: Fermi GBM Final Real-time Localization
  41. Fermi GBM Sub-Threshold Detection of GRB 260705A
  42. GRB 260705A: SVOM detection of a burst
  43. GRB 260704A: EP-FXT follow-up observation
  44. GRB 260704A: SVOM detection of a possible GRB
  45. GRB 260703B: Fermi GBM Final Localization
  46. Fermi trigger No 804738310: Global MASTER-Net observations report
  47. Fermi GRB 260703A: Global MASTER-Net observations report
  48. GRB 260703A: Fermi GBM Final Localization
  49. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  50. Fermi trigger No 804552016: Global MASTER-Net observations report
  51. GRB 260701A: Fermi GBM Final Real-time Localization
  52. Fermi GBM trigger 804552016/260630945 is not a GRB
  53. GRB 260629A: Fermi GBM Final Real-time Localization
  54. Fermi GRB 260628A: Global MASTER-Net observations report
  55. GRB 260628A: Fermi GBM Final Real-time Localization
  56. The EP-WXT trigger 01709272671 is likely a flaring star
  57. EP260626a: further Liverpool Telescope optical upper limits
  58. EP260626a: COLIBRÍ optical upper limit
  59. EP260623a: TNG NIR afterglow detection
  60. GRB 260618A: Fermi GBM Observation
  61. EP260623a: FTW optical and NIR observations
  62. EP260623a: Liverpool Telescope optical observations
  63. Fermi GBM trigger 804010507/260624677 is not a GRB
  64. GRB 260624A: Fermi GBM Final Real-time Localization
  65. EP260623a: WINTER J-band observations
  66. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  67. GRB 260623A: Fermi GBM Final Real-time Localization
  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. EP260623a: OSIRIS+/GTC redshift z = 0.703
  73. EP260623a: Las Cumbres discovery of the optical counterpart
  74. GRB 260614B: EP-FXT follow-up observation
  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 260619A: SVOM/VT optical counterpart confirmation
  85. GRB 260618B: SVOM/VT optical candidate
  86. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  87. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  88. Konus-Wind detection of GRB 260617A
  89. EP260618a: OHP/T193 optical observations
  90. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  91. EP260618a: LCO optical counterpart confirmation
  92. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  93. EP260618a: COLIBRÍ optical counterpart candidate
  94. GRB 260619A: SVOM possible detection of a faint burst
  95. GRB 260618B: Fermi-LAT detection
  96. IPN triangulation of GRB 260617A (short)
  97. GRB 260618B: Fermi GBM Final Real-time Localization
  98. GRB 260610B: AbAO optical observations
  99. GRB 260618A: Fermi GBM Final Real-time Localization
  100. GRB 260617A: Fermi GBM Detection

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