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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

42476 results found.

  1. GRB 251103A: J-band detection with WINTER
  2. Swift GRB 251103B: Global MASTER-Net observations report
  3. GRB 251103B: GROWTH-India Telescope optical upper limits
  4. GRB 251103A: Kilonova-Catcher optical afterglow detection
  5. GRB 251103B: Enhanced Swift-XRT position
  6. GRB 251103B: Prompt enhanced Swift-XRT position
  7. GRB 251103B: Swift detection of a burst
  8. GRB 251103B: Fermi GBM Final Real-time Localization
  9. GRB 251103A: Swift/UVOT Detection
  10. GRB 251103A: Fermi GBM Observation
  11. GRB 251103A: SVOM/GRM observation
  12. GRB 251103A: Swift-XRT afterglow detection
  13. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  14. EP251102a: Einstein Probe detection of a fast X-ray transient
  15. GRB 251025B: OHP/T193 optical upper limit
  16. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  17. GRB 251103A: LCO optical observation
  18. EP251102.890: COLIBRÍ optical counterpart candidate
  19. GRB 251103A: GOTO optical afterglow detection
  20. GRB 251102A: AstroSat CZTI detection
  21. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  22. GRB 251103A: NOT spectroscopic redshift z = 0.76
  23. GRB 251103A: BOOTES-2/TELMA optical afterglow
  24. GRB 251103A: LCO optical afterglow detection
  25. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  26. GRB 251103A: Fermi GBM Final Localization
  27. GRB 251103A: NOT optical afterglow candidate
  28. GRB 251103A: SVOM detection of a bright burst
  29. GRB 251102B: Fermi GBM Final Real-time Localization
  30. Fermi GRB 251102A: Global MASTER-Net observations report
  31. GRB 251102A: Fermi GBM Final Real-time Localization
  32. GRB 251031A: Fermi GBM Observation
  33. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  34. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  35. Konus-Wind detection of GRB 251028A
  36. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  37. GRB 251031A: Fermi GBM Final Real-time Localization
  38. GRB 251025C: SVOM/GRM observation
  39. GRB 251028A: GECAM-B detection
  40. GRB 251028A: SVOM/GRM observation
  41. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  42. GRB 251028A: Fermi GBM Observation
  43. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  44. GRB 251022A: Swift-XRT confirmation of fading
  45. GRB 251026B: LBT near-infrared observations
  46. GRB 251026B: Fermi GBM Observation
  47. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  48. GRB 251026A/EP251026a: EP-FXT follow-up observation
  49. The EP-WXT trigger 01709247588 is likely a flaring star
  50. GRB 251028B: Fermi/GBM observation
  51. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  52. GRB 251028B: Glowbug gamma-ray detection
  53. GRB 251028A: Glowbug gamma-ray detection
  54. Fermi GRB 251028B: Global MASTER-Net observations report
  55. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  56. GRB 251028B: Fermi GBM Final Localization Correction
  57. GRB251026B: PRIME H-band upper limit
  58. GRB251025B: 3.6m DOT Optical Observations
  59. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  60. GRB 251028A: MAXI/GSC detection
  61. GRB 251028A: Fermi GBM Final Real-time Localization
  62. SVOM trigger sb25102702/GRB 251027A is not a GRB
  63. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 251025B: Swift-XRT confirmation of fading
  65. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  66. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  67. GRB 251025C: Glowbug gamma-ray detection
  68. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  69. GRB 251023B: Swift-UVOT Upper Limits
  70. Konus-Wind detection of GRB 251022A
  71. GRB 251027A: Swift-XRT observations
  72. EP251027.145: COLIBRÍ optical upper limits
  73. GRB 251022A: SVOM/GRM observation
  74. GRB 251026B: Swift ToO observations
  75. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  76. GRB 251027A: LCO optical upper limit
  77. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  79. GRB 251023B / EP251023b: Mondy optical upper limit
  80. GRB 251017A: INASAN-Kislovodsk optical observations
  81. GRB 251026A: Mondy optical upper limit
  82. GRB 251025B: Mondy optical observations
  83. GRB 251025B: Kilonova-Catcher optical afterglow detection
  84. Konus-Wind detection of GRB 251016A (short/hard)
  85. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  86. GRB 251027A: SVOM detection of a faint burst
  87. GRB 251026B: Tentative GOTO optical counterpart candidate
  88. GRB 251025C: AstroSat CZTI detection
  89. EP251023a: Mondy optical observations
  90. GRB 251025B: MAO/AZT-22 optical observations
  91. Fermi GRB 251026B: Global MASTER-Net observations report
  92. Fermi GRB 251025C: Global MASTER-Net observations report
  93. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  94. GRB 251026A: Swift-XRT observations
  95. GRB 251025B: OHP/T193 optical detection
  96. GRB 251025B: J-band detection with WINTER
  97. GRB 251026A: SVOM/C-GFT upper limit
  98. IceCube-251025A: DDOTI Optical Upper Limit
  99. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  100. GRB 251026B: Fermi GBM Final Localization

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