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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"

37500 results found.

  1. EP251023b/GRB 251023B: JinShan optical observation
  2. GRB 251022A: Swift-XRT detection of GOTO25iym
  3. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  4. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  5. GRB 251022A: GROWTH-India Telescope optical observations
  6. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  7. GRB 251022A: Fermi GBM Observation
  8. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  9. GRB 251023A: Glowbug gamma-ray detection
  10. GRB 251023B: Glowbug gamma-ray detection
  11. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  12. IPN triangulation of GRB 251016B
  13. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  14. EP#01709247298: Swift-XRT counterpart detection
  15. GRB 251013C: further SAO RAS optical observations
  16. GRB 251022A: COLIBRÍ optical observations
  17. GRB 251013C: ISON-Castelgrande observatory optical observations
  18. GRB 251022A: MASTER OT detection
  19. GRB 251022A: DDOTI Optical Detection
  20. EP251021b/GRB 251021A: SVOM/VT optical candidate
  21. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  22. Fermi GRB 251023A: Global MASTER-Net observations report
  23. GRB 251022A: GOTO optical counterpart detection
  24. GRB 251023A: Fermi GBM Final Localization Correction
  25. GRB 251022A: Fermi-LAT detection
  26. GRB 251016B: Fermi GBM Detection
  27. GRB 251022A: Tiled Swift observations
  28. GRB 251022A: Fermi GBM Final Real-time Localization
  29. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  30. GRB 250911A: MAXI/GSC detection
  31. GRB 251016A: SVOM/ECLAIRs refined analysis
  32. Fermi-LAT gamma-ray observations of IceCube-251018A
  33. GRB 251017A : RAPAS follow-up observations
  34. GRB 251017A: COLIBRÍ optical observations of a late plateau
  35. GRB 251017A: Swift-BAT refined analysis
  36. GRB 251016A: Fermi GBM Observation
  37. GRB 251018A: Fermi GBM Observation
  38. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  39. GRB 251018A: Swift-XRT refined Analysis
  40. GRB 251018A: Enhanced Swift-XRT position
  41. Fermi trigger No 782500909: Global MASTER-Net observations report
  42. GRB 251016A: HXMT/HE detection
  43. GRB 251016A: Swift-XRT afterglow detection
  44. GRB 251017A: Swift/UVOT Detection
  45. GRB 251016A: Swift/UVOT Detection
  46. GRB 251018A: Swift/UVOT Detection
  47. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  48. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  49. GRB 251016A: VLT/FORS2 Optical Observation
  50. GRB 251017A: COLIBRÍ photometric redshift
  51. GRB 251017A: Swift-XRT refined Analysis
  52. GRB 251018A: MASTER OT detection
  53. GRB 251018A: TRT optical afterglow detection
  54. Swift GRB 251018A: Global MASTER-Net observations report
  55. GRB 251018A: Swift detection of a burst with an optical counterpart
  56. GRB 251018A: Fermi GBM Final Real-time Localization
  57. GRB 251017A: SVOM/VT optical observation
  58. GRB 251011A: Fermi GBM Observation
  59. GRB 251017A: OHP/T193 i-band observations
  60. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  61. GRB 251017A: J-band detection with WINTER
  62. GRB 251017A: Glowbug gamma-ray detection
  63. GRB 251013C: Liverpool Telescope observations
  64. GRB 251013C: Leavitt Observatory optical photometry
  65. Fermi GRB 251016B: Global MASTER-Net observations report
  66. GRB 251017A: JinShan observations of the optical afterglow
  67. Swift GRB 251017A: Global MASTER-Net observations report
  68. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  69. Swift Trigger 1404295 is not a GRB
  70. GRB 251016A: AstroSat CZTI detection of a short burst
  71. GRB 251017A: Enhanced Swift-XRT position
  72. GRB 251017A: COLIBRÍ Early Afterglow Detection
  73. GRB 251016B: AstroSat CZTI detection
  74. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  75. GRB 251017A: Swift detection of a burst with an optical counterpart
  76. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  78. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  79. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  80. GRB 251007B: Swift-BAT refined analysis
  81. GRB 251016B: Fermi GBM Final Real-time Localization
  82. GRB 251014D: Swift-BAT refined analysis
  83. GRB 251016A: BOOTES-6/DPRT optical upper limit
  84. GRB 251016A: Glowbug gamma-ray detection of a short burst
  85. GRB 251013C: VLA detection
  86. Fermi GRB 251016A: Global MASTER-Net observations report
  87. GRB 251016A: Fermi GBM Final Localization
  88. GRB 251016A: SVOM detection of a short burst
  89. GRB 251014A: Swift-XRT observations
  90. GRB 251014B: PRIME J-band upper limit
  91. GRB 251013C: Kilonova-Catcher optical afterglow detection
  92. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  93. GRB 251013D: Swift/UVOT Observations
  94. GRB 251013C: Swift/UVOT Detection
  95. Konus-Wind detection of GRB 251007A
  96. Fermi Gamma-ray Burst Monitor trigger 782237334/251015673 is not a GRB
  97. GRB 251013C, GCN Circular 42267, errata corrige
  98. GRB 251013C: detection of a radio counterpart at 15.5GHz
  99. GRB 251015A: Fermi GBM Final Real-time Localization
  100. GRB 251013C: SVOM/ECLAIRs refined analysis

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