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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"

24385 results found.

  1. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  2. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  3. Konus-Wind detection of GRB 251028A
  4. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  5. GRB 251031A: Fermi GBM Final Real-time Localization
  6. GRB 251025C: SVOM/GRM observation
  7. GRB 251028A: GECAM-B detection
  8. GRB 251028A: SVOM/GRM observation
  9. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  10. GRB 251028A: Fermi GBM Observation
  11. GRB 251022A: Swift-XRT confirmation of fading
  12. GRB 250926B: VZLUSAT-2 detection
  13. GRB 250926A: VZLUSAT-2 detection
  14. GRB 250925A: VZLUSAT-2 detection
  15. GRB 251026B: Fermi GBM Observation
  16. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  17. GRB 251026A/EP251026a: EP-FXT follow-up observation
  18. The EP-WXT trigger 01709247588 is likely a flaring star
  19. GRB 251028B: Fermi/GBM observation
  20. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  21. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  22. Fermi GRB 251028B: Global MASTER-Net observations report
  23. GRB 251028B: Fermi GBM Final Localization Correction
  24. GRB251025B: 3.6m DOT Optical Observations
  25. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  26. GRB 251028A: Fermi GBM Final Real-time Localization
  27. The EP-WXT trigger 01709247525 is not a real source
  28. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  29. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  30. Konus-Wind detection of GRB 251022A
  31. GRB 251022A: SVOM/GRM observation
  32. Konus-Wind detection of GRB 251016A (short/hard)
  33. GRB 251027A: SVOM detection of a faint burst
  34. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  35. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  36. Fermi GRB 251026B: Global MASTER-Net observations report
  37. Fermi GRB 251025C: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  39. IceCube-251025A: DDOTI Optical Upper Limit
  40. GRB 251026B: Fermi GBM Final Localization
  41. GRB 251026A: SVOM detection of a long burst
  42. GRB 251025B: SVOM/VT optical bump
  43. GRB 251023A: SVOM/GRM observation
  44. GRB 251025C: Fermi GBM Final Real-time Localization
  45. Konus-Wind detection of GRB 251016B
  46. GRB 251024A: Swift-BAT refined analysis
  47. IceCube Alert 251025.57: Global MASTER-Net observations report
  48. GRB 251024A: Swift-XRT refined Analysis
  49. GRB 251025B: SVOM/C-GFT optical counterpart detection
  50. GRB 251025B: SVOM detection of a burst
  51. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  52. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  53. GRB 251025A: SVOM/VT VHF optical upper limit
  54. GRB 251025A: SVOM detection of a faint burst
  55. GRB 251023C: Glowbug gamma-ray detection
  56. GRB 251024A: LCOGT Optical Afterglow Detection
  57. GRB 251022A: KAIT optical observations
  58. Swift GRB 251024A: Global MASTER-Net observations report
  59. EP251023b/GRB 251023B: JinShan optical observation
  60. GRB 251022A: Swift-XRT detection of GOTO25iym
  61. EP251023b: Global MASTER-Net observations report
  62. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  63. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  64. GRB 251022A: Fermi GBM Observation
  65. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  66. EP251023a: Global MASTER-Net observations report
  67. IPN triangulation of GRB 251016B
  68. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  69. GRB 251022A: MASTER OT detection
  70. EP251021b/GRB 251021A: SVOM/VT optical candidate
  71. EP251023a: NOT optical counterpart detection
  72. Fermi GRB 251023A: Global MASTER-Net observations report
  73. GRB 251022A: GOTO optical counterpart detection
  74. GRB 251023A: Fermi GBM Final Localization Correction
  75. GRB 251022A: Fermi-LAT detection
  76. GRB 251016B: Fermi GBM Detection
  77. LAT GRB251022A: Global MASTER-Net observations report
  78. GRB 251022A: Fermi GBM Final Real-time Localization
  79. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  80. EP251021b: BOOTES-7 optical upper limit
  81. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  82. GRB 251016A: SVOM/ECLAIRs refined analysis
  83. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  85. Fermi-LAT gamma-ray observations of IceCube-251018A
  86. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  87. GRB 251017A: Swift-BAT refined analysis
  88. GRB 251016A: Fermi GBM Observation
  89. GRB 251018A: Fermi GBM Observation
  90. Fermi trigger No 782500909: Global MASTER-Net observations report
  91. IceCube-251018A: Global MASTER-Net observations report
  92. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  93. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  94. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  95. GRB 251016A: VLT/FORS2 Optical Observation
  96. GRB 251017A: Swift-XRT refined Analysis
  97. GRB 251018A: MASTER OT detection
  98. Swift GRB 251018A: Global MASTER-Net observations report
  99. GRB 251018A: Fermi GBM Final Real-time Localization
  100. GRB 251017A: SVOM/VT optical observation

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