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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"

20982 results found.

  1. GRB 251022A: Swift-XRT confirmation of fading
  2. GRB 251026B: LBT near-infrared observations
  3. GRB 251026A/EP251026a: EP-FXT follow-up observation
  4. Fermi GRB 251028B: Global MASTER-Net observations report
  5. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  6. GRB251026B: PRIME H-band upper limit
  7. GRB251025B: 3.6m DOT Optical Observations
  8. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  9. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  10. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  11. GRB 251023B: Swift-UVOT Upper Limits
  12. GRB 251027A: Swift-XRT observations
  13. GRB 251026B: Swift ToO observations
  14. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  15. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  16. GRB 251017A: INASAN-Kislovodsk optical observations
  17. GRB 251025B: Mondy optical observations
  18. GRB 251025B: Kilonova-Catcher optical afterglow detection
  19. GRB 251027A: SVOM detection of a faint burst
  20. GRB 251026B: Tentative GOTO optical counterpart candidate
  21. EP251023a: Mondy optical observations
  22. GRB 251025B: MAO/AZT-22 optical observations
  23. Fermi GRB 251026B: Global MASTER-Net observations report
  24. Fermi GRB 251025C: Global MASTER-Net observations report
  25. GRB 251026A: Swift-XRT observations
  26. GRB 251025B: OHP/T193 optical detection
  27. GRB 251025B: J-band detection with WINTER
  28. GRB 251026A: SVOM/C-GFT upper limit
  29. IceCube-251025A: DDOTI Optical Upper Limit
  30. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  32. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  33. GRB 251025B: GROWTH-India Telescope optical observations
  34. GRB 251024A: Swift/UVOT Upper Limits
  35. GRB 251025B: Swift-XRT afterglow detection
  36. IceCube Alert 251025.57: Global MASTER-Net observations report
  37. GRB 251025A (sb25102501): stellar flare confirmed
  38. GRB 251025B: SVOM/VT optical observations with VHF data
  39. GRB 251025B: MASTER OT detection
  40. GRB 251025B: SVOM/C-GFT optical counterpart detection
  41. GRB 251003A: VLA Detection
  42. GRB 251022A: KAIT optical observations
  43. Swift GRB 251024A: Global MASTER-Net observations report
  44. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  45. EP251023a: MAO/AZT-22 optical observations
  46. GRB 251023B: OHP/T193 optical observations
  47. EP251023a: OHP/T193 optical observations
  48. EP251023b/GRB 251023B: JinShan optical observation
  49. GRB 251022A: Swift-XRT detection of GOTO25iym
  50. EP251023b: Global MASTER-Net observations report
  51. GRB 251022A: GROWTH-India Telescope optical observations
  52. EP251023a: GROWTH-India Telescope optical observations
  53. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  54. EP251023a: Global MASTER-Net observations report
  55. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  56. EP#01709247298: Swift-XRT counterpart detection
  57. EP251023a: COLIBRÍ optical observations
  58. GRB 251013C: further SAO RAS optical observations
  59. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  60. GRB 251022A: COLIBRÍ optical observations
  61. GRB 251013C: ISON-Castelgrande observatory optical observations
  62. GRB 251022A: MASTER OT detection
  63. GRB 251022A: DDOTI Optical Detection
  64. Fermi GRB 251023A: Global MASTER-Net observations report
  65. EP251023a: GSP Optical Counterpart Detection
  66. EP/WXT 01709247295: GOTO optical afterglow candidate.
  67. GRB 251022A: GOTO optical counterpart detection
  68. GRB 251022A: Tiled Swift observations
  69. LAT GRB251022A: Global MASTER-Net observations report
  70. GRB 251016A: SVOM/ECLAIRs refined analysis
  71. Fermi-LAT gamma-ray observations of IceCube-251018A
  72. GRB 251017A : RAPAS follow-up observations
  73. GRB 251017A: COLIBRÍ optical observations of a late plateau
  74. IceCube-251018A: DDOTI Optical Upper Limit
  75. Fermi trigger No 782500909: Global MASTER-Net observations report
  76. IceCube-251018A: Global MASTER-Net observations report
  77. GRB 251016A: Swift-XRT afterglow detection
  78. GRB 251017A: Swift/UVOT Detection
  79. GRB 251016A: Swift/UVOT Detection
  80. GRB 251018A: Swift/UVOT Detection
  81. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  82. GRB 251016A: VLT/FORS2 Optical Observation
  83. GRB 251017A: COLIBRÍ photometric redshift
  84. GRB 251018A: MASTER OT detection
  85. GRB 251018A: TRT optical afterglow detection
  86. Swift GRB 251018A: Global MASTER-Net observations report
  87. GRB 251017A: OHP/T193 i-band observations
  88. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  89. GRB 251017A: J-band detection with WINTER
  90. GRB 251013C: Liverpool Telescope observations
  91. GRB 251013C: Leavitt Observatory optical photometry
  92. Fermi GRB 251016B: Global MASTER-Net observations report
  93. GRB 251017A: JinShan observations of the optical afterglow
  94. Swift GRB 251017A: Global MASTER-Net observations report
  95. GRB 251017A: COLIBRÍ Early Afterglow Detection
  96. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  97. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  98. GRB 251013C: VLA detection
  99. sb25101602: Swift-XRT counterpart detection
  100. Fermi GRB 251016A: Global MASTER-Net observations report

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