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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"
  1. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  2. LAT GRB260708.42: Global MASTER-Net observations report
  3. GRB260708B: MAXI/GSC detection
  4. GRB 260708A: Fermi-LAT detection
  5. GRB 260705B: SVOM/GRM observation
  6. GRB 260708A: Fermi-GBM detection
  7. GRB 260706A: Further EP-FXT follow-up observation
  8. GRB 260706A: SVOM/VT optical upper limits
  9. EP260707a (by EP-FXT): NOT optical upper limit
  10. EP260707a is not a real source
  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. EP260707a: Einstein Probe detection of an X-ray transient
  15. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  16. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  17. GRB 260705C: Glowbug gamma-ray detection of a short burst
  18. GRB 260706A: SVOM/ECLAIRs refined analysis
  19. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  20. GRB 260706A: SVOM/GRM observation
  21. GRB 260706A: REM optical/NIR observations
  22. IceCube-260704A: No candidates from the Zwicky Transient Facility
  23. GRB 260706A: LCO optical upper limit
  24. GRB 260706A: EP-FXT follow-up observation
  25. GRB 260707A: Fermi GBM Final Real-time Localization
  26. The EP-WXT trigger 01709274151 is likely a flaring star
  27. The EP-WXT trigger 01709274141 is likely a flaring star
  28. GRB 260706A: Fermi GBM Observation
  29. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  30. IPN triangulation of GRB 260627A
  31. GRB 260705A: SVOM/ECLAIRs refined analysis
  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 260629A: SVOM/GRM observation of a short burst
  45. GRB 260629A: GECAM-A observation of a short burst
  46. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  47. GRB 260629A: AstroSat CZTI detection
  48. EP260703a: EP-FXT follow-up observation
  49. GRB 260704A: SVOM detection of a possible GRB
  50. GRB 260703B: Fermi GBM Final Localization
  51. EP260703a: EP-WXT detection of a fast X-ray transient
  52. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  53. Fermi trigger No 804738310: Global MASTER-Net observations report
  54. Fermi GRB 260703A: Global MASTER-Net observations report
  55. GRB 260703A: Fermi GBM Final Localization
  56. GRB 260610B: VLA detection
  57. GRB 260623A: Glowbug gamma-ray detection
  58. GRB 260614B: ATCA Radio Upper Limits
  59. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  60. Fermi trigger No 804552016: Global MASTER-Net observations report
  61. GRB 260701A: Fermi GBM Final Real-time Localization
  62. Fermi GBM trigger 804552016/260630945 is not a GRB
  63. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  64. EP260628a: EP-FXT follow-up observation
  65. GRB 260629A: Fermi GBM Final Real-time Localization
  66. Fermi GRB 260628A: Global MASTER-Net observations report
  67. EP260628a: EP-WXT detection of a fast X-ray transient
  68. GRB 260628A: Fermi GBM Final Real-time Localization
  69. The EP-WXT trigger 01709272671 is likely a flaring star
  70. EP260626a: further Liverpool Telescope optical upper limits
  71. EP260626a: EP-FXT follow-up observation
  72. EP260626a: COLIBRÍ optical upper limit
  73. EP260626a: Liverpool Telescope upper limits
  74. EP260626a: EP-WXT detection of a fast X-ray transient
  75. Konus-Wind detection of GRB 260623B / EP260623a
  76. EP260623a: TNG NIR afterglow detection
  77. GRB 260618A: Fermi GBM Observation
  78. MASS-Cube (GRID 2.0) detection of GRB 260616B
  79. EP260623a: FTW optical and NIR observations
  80. GRB 260619A: SVOM/ECLAIRs refined analysis
  81. EP260623a: Liverpool Telescope optical observations
  82. Fermi GBM trigger 804010507/260624677 is not a GRB
  83. Konus-Wind detection of GRB 260618B
  84. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  85. GRB 260624A: Fermi GBM Final Real-time Localization
  86. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  87. EP260623a: WINTER J-band observations
  88. GRB 260617A: Glowbug gamma-ray detection of a short burst
  89. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  90. IPN triangulation of GRB 260605A
  91. EP260623a: Optical follow-up observations with Kinder
  92. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  93. GRB 260623A: Fermi GBM Final Real-time Localization
  94. EP260623a: SVOM/VT optical observations
  95. EP260623a: TRT optical observations
  96. EP260623a: REM optical/NIR afterglow detection
  97. EP 260623a: COLIBRÍ optical observations
  98. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  99. EP260623a: OSIRIS+/GTC redshift z = 0.703
  100. EP260623a: Las Cumbres discovery of the optical counterpart

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