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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"

42468 results found.

  1. GRB 251103A: Swift/UVOT Detection
  2. GRB 251103A: Fermi GBM Observation
  3. GRB 251103A: SVOM/GRM observation
  4. GRB 251103A: Swift-XRT afterglow detection
  5. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  6. EP251102a: Einstein Probe detection of a fast X-ray transient
  7. GRB 251025B: OHP/T193 optical upper limit
  8. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  9. GRB 251103A: LCO optical observation
  10. EP251102.890: COLIBRÍ optical counterpart candidate
  11. GRB 251103A: GOTO optical afterglow detection
  12. GRB 251102A: AstroSat CZTI detection
  13. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  14. GRB 251103A: NOT spectroscopic redshift z = 0.76
  15. GRB 251103A: BOOTES-2/TELMA optical afterglow
  16. GRB 251103A: LCO optical afterglow detection
  17. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  18. GRB 251103A: Fermi GBM Final Localization
  19. GRB 251103A: NOT optical afterglow candidate
  20. GRB 251103A: SVOM detection of a bright burst
  21. GRB 251102B: Fermi GBM Final Real-time Localization
  22. Fermi GRB 251102A: Global MASTER-Net observations report
  23. GRB 251102A: Fermi GBM Final Real-time Localization
  24. GRB 251031A: Fermi GBM Observation
  25. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  26. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  27. Konus-Wind detection of GRB 251028A
  28. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  29. GRB 251031A: Fermi GBM Final Real-time Localization
  30. GRB 251025C: SVOM/GRM observation
  31. GRB 251028A: GECAM-B detection
  32. GRB 251028A: SVOM/GRM observation
  33. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  34. GRB 251028A: Fermi GBM Observation
  35. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  36. GRB 251022A: Swift-XRT confirmation of fading
  37. GRB 251026B: LBT near-infrared observations
  38. GRB 251026B: Fermi GBM Observation
  39. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  40. GRB 251026A/EP251026a: EP-FXT follow-up observation
  41. The EP-WXT trigger 01709247588 is likely a flaring star
  42. GRB 251028B: Fermi/GBM observation
  43. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  44. GRB 251028B: Glowbug gamma-ray detection
  45. GRB 251028A: Glowbug gamma-ray detection
  46. Fermi GRB 251028B: Global MASTER-Net observations report
  47. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  48. GRB 251028B: Fermi GBM Final Localization Correction
  49. GRB251026B: PRIME H-band upper limit
  50. GRB251025B: 3.6m DOT Optical Observations
  51. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  52. GRB 251028A: MAXI/GSC detection
  53. GRB 251028A: Fermi GBM Final Real-time Localization
  54. SVOM trigger sb25102702/GRB 251027A is not a GRB
  55. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB 251025B: Swift-XRT confirmation of fading
  57. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  58. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  59. GRB 251025C: Glowbug gamma-ray detection
  60. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  61. GRB 251023B: Swift-UVOT Upper Limits
  62. Konus-Wind detection of GRB 251022A
  63. GRB 251027A: Swift-XRT observations
  64. EP251027.145: COLIBRÍ optical upper limits
  65. GRB 251022A: SVOM/GRM observation
  66. GRB 251026B: Swift ToO observations
  67. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  68. GRB 251027A: LCO optical upper limit
  69. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  71. GRB 251023B / EP251023b: Mondy optical upper limit
  72. GRB 251017A: INASAN-Kislovodsk optical observations
  73. GRB 251026A: Mondy optical upper limit
  74. GRB 251025B: Mondy optical observations
  75. GRB 251025B: Kilonova-Catcher optical afterglow detection
  76. Konus-Wind detection of GRB 251016A (short/hard)
  77. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  78. GRB 251027A: SVOM detection of a faint burst
  79. GRB 251026B: Tentative GOTO optical counterpart candidate
  80. GRB 251025C: AstroSat CZTI detection
  81. EP251023a: Mondy optical observations
  82. GRB 251025B: MAO/AZT-22 optical observations
  83. Fermi GRB 251026B: Global MASTER-Net observations report
  84. Fermi GRB 251025C: Global MASTER-Net observations report
  85. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  86. GRB 251026A: Swift-XRT observations
  87. GRB 251025B: OHP/T193 optical detection
  88. GRB 251025B: J-band detection with WINTER
  89. GRB 251026A: SVOM/C-GFT upper limit
  90. IceCube-251025A: DDOTI Optical Upper Limit
  91. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  92. GRB 251026B: Fermi GBM Final Localization
  93. GRB 251026A: SVOM detection of a long burst
  94. GRB 251025B: SVOM/VT optical bump
  95. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  96. GRB 251023A: SVOM/GRM observation
  97. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  98. GRB 251025C: Fermi GBM Final Real-time Localization
  99. Konus-Wind detection of GRB 251016B
  100. GRB 251025B: GROWTH-India Telescope optical observations

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