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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"

24398 results found.

  1. GRB 251103B: GROWTH-India Telescope optical upper limits
  2. GRB 251103B: Fermi GBM Final Real-time Localization
  3. GRB 251103A: Fermi GBM Observation
  4. GRB 251103A: SVOM/GRM observation
  5. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  6. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  7. GRB 251103A: LCO optical afterglow detection
  8. GRB 251103A: Fermi GBM Final Localization
  9. GRB 251103A: SVOM detection of a bright burst
  10. GRB 251102B: Fermi GBM Final Real-time Localization
  11. Fermi GRB 251102A: Global MASTER-Net observations report
  12. GRB 251102A: Fermi GBM Final Real-time Localization
  13. GRB 251031A: Fermi GBM Observation
  14. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  15. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  16. Konus-Wind detection of GRB 251028A
  17. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  18. GRB 251031A: Fermi GBM Final Real-time Localization
  19. GRB 251025C: SVOM/GRM observation
  20. GRB 251028A: GECAM-B detection
  21. GRB 251028A: SVOM/GRM observation
  22. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  23. GRB 251028A: Fermi GBM Observation
  24. GRB 251022A: Swift-XRT confirmation of fading
  25. GRB 250926B: VZLUSAT-2 detection
  26. GRB 250926A: VZLUSAT-2 detection
  27. GRB 250925A: VZLUSAT-2 detection
  28. GRB 251026B: Fermi GBM Observation
  29. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  30. GRB 251026A/EP251026a: EP-FXT follow-up observation
  31. The EP-WXT trigger 01709247588 is likely a flaring star
  32. GRB 251028B: Fermi/GBM observation
  33. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  34. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  35. Fermi GRB 251028B: Global MASTER-Net observations report
  36. GRB 251028B: Fermi GBM Final Localization Correction
  37. GRB251025B: 3.6m DOT Optical Observations
  38. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  39. GRB 251028A: Fermi GBM Final Real-time Localization
  40. The EP-WXT trigger 01709247525 is not a real source
  41. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  42. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  43. Konus-Wind detection of GRB 251022A
  44. GRB 251022A: SVOM/GRM observation
  45. Konus-Wind detection of GRB 251016A (short/hard)
  46. GRB 251027A: SVOM detection of a faint burst
  47. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  48. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  49. Fermi GRB 251026B: Global MASTER-Net observations report
  50. Fermi GRB 251025C: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  52. IceCube-251025A: DDOTI Optical Upper Limit
  53. GRB 251026B: Fermi GBM Final Localization
  54. GRB 251026A: SVOM detection of a long burst
  55. GRB 251025B: SVOM/VT optical bump
  56. GRB 251023A: SVOM/GRM observation
  57. GRB 251025C: Fermi GBM Final Real-time Localization
  58. Konus-Wind detection of GRB 251016B
  59. GRB 251024A: Swift-BAT refined analysis
  60. IceCube Alert 251025.57: Global MASTER-Net observations report
  61. GRB 251024A: Swift-XRT refined Analysis
  62. GRB 251025B: SVOM/C-GFT optical counterpart detection
  63. GRB 251025B: SVOM detection of a burst
  64. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  65. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB 251025A: SVOM/VT VHF optical upper limit
  67. GRB 251025A: SVOM detection of a faint burst
  68. GRB 251023C: Glowbug gamma-ray detection
  69. GRB 251024A: LCOGT Optical Afterglow Detection
  70. GRB 251022A: KAIT optical observations
  71. Swift GRB 251024A: Global MASTER-Net observations report
  72. EP251023b/GRB 251023B: JinShan optical observation
  73. GRB 251022A: Swift-XRT detection of GOTO25iym
  74. EP251023b: Global MASTER-Net observations report
  75. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  76. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  77. GRB 251022A: Fermi GBM Observation
  78. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  79. EP251023a: Global MASTER-Net observations report
  80. IPN triangulation of GRB 251016B
  81. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  82. GRB 251022A: MASTER OT detection
  83. EP251021b/GRB 251021A: SVOM/VT optical candidate
  84. EP251023a: NOT optical counterpart detection
  85. Fermi GRB 251023A: Global MASTER-Net observations report
  86. GRB 251022A: GOTO optical counterpart detection
  87. GRB 251023A: Fermi GBM Final Localization Correction
  88. GRB 251022A: Fermi-LAT detection
  89. GRB 251016B: Fermi GBM Detection
  90. LAT GRB251022A: Global MASTER-Net observations report
  91. GRB 251022A: Fermi GBM Final Real-time Localization
  92. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  93. EP251021b: BOOTES-7 optical upper limit
  94. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  95. GRB 251016A: SVOM/ECLAIRs refined analysis
  96. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  98. Fermi-LAT gamma-ray observations of IceCube-251018A
  99. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 251017A: Swift-BAT refined analysis

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