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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"

26053 results found.

  1. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  2. GRB 251116C: SVOM/ECLAIRs refined analysis
  3. GRB 251117A: AstroSat CZTI detection
  4. GRB 251117A: Fermi GBM observation
  5. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  6. GRB 251115A: Swift-XRT observations
  7. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  8. GRB 251117A: Tiled Swift observations
  9. GRB 251117A: Fermi-LAT detection
  10. GRB 251116C: Swift/BAT arcminute localization of a burst
  11. GRB 251116C: Swift-XRT observations
  12. GRB 251116C: SVOM/VT optical upper limit
  13. GRB 251115A: Tiled Swift observations
  14. GRB 251115A: Fermi-LAT detection
  15. GRB 251112A: Swift-BAT refined analysis
  16. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  17. GRB 251112A: Swift/UVOT Upper Limits
  18. GRB 251112A: Swift-XRT refined Analysis
  19. Swift Trigger 1413695: a possible GRB 251112A
  20. GRB251111A: 1.3m DFOT optical upper limit
  21. GRB 251111A: Swift-XRT afterglow detection
  22. GRB 251111A: Swift-XRT observations
  23. GRB 251013C: Chandra X-ray observations and jet break detection
  24. GRB 251111A: KAIT optical upper limit
  25. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  26. GRB 251103B: Swift-BAT refined analysis
  27. GRB 251106A: Swift/UVOT Upper Limits
  28. GRB 251105A: AstroSat CZTI detection
  29. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  30. GRB 251106A: Swift-XRT afterglow detection
  31. GRB 251106A: Kilonova-Catcher optical upper limit
  32. GRB 251106A: Swift/BAT arcminute localization of a burst
  33. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  34. GRB 251103B: AstroSat CZTI detection
  35. GRB 250920C: TERI Gamma-ray detection
  36. GRB 251105A: Fermi GBM Observation
  37. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  38. GRB 251103B: Swift/UVOT Upper Limits
  39. GRB 251103B: Fermi GBM observation
  40. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  41. GRB 251103A: WFST optical observations
  42. EP251102a: OHP/T193 optical observations
  43. GRB 251103A: OHP/T193 optical observations
  44. GRB 251103A: Xinglong 2.16m optical detection
  45. GRB 251103A: KAIT optical observations
  46. GRB 251103B: Nanshan/HMT optical upper limit
  47. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  48. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  49. GRB 251103B: MITSuME Akeno optical upper limits
  50. GRB 251103B: Swift-XRT refined Analysis
  51. Swift GRB 251103B: Global MASTER-Net observations report
  52. GRB 251103B: GROWTH-India Telescope optical upper limits
  53. GRB 251103A: Kilonova-Catcher optical afterglow detection
  54. GRB 251103B: Enhanced Swift-XRT position
  55. GRB 251103B: Prompt enhanced Swift-XRT position
  56. GRB 251103B: Swift detection of a burst
  57. GRB 251103A: Swift/UVOT Detection
  58. GRB 251103A: Swift-XRT afterglow detection
  59. GRB 251025B: OHP/T193 optical upper limit
  60. GRB 251103A: GOTO optical afterglow detection
  61. GRB 251103A: NOT spectroscopic redshift z = 0.76
  62. GRB 251103A: BOOTES-2/TELMA optical afterglow
  63. GRB 251103A: LCO optical afterglow detection
  64. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  65. GRB 251103A: NOT optical afterglow candidate
  66. GRB 251031A: Fermi GBM Observation
  67. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  68. GRB 251022A: Swift-XRT confirmation of fading
  69. GRB 251026B: LBT near-infrared observations
  70. GRB 250925A: VZLUSAT-2 detection
  71. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  72. GRB 251028B: Fermi/GBM observation
  73. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  74. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  75. GRB251025B: 3.6m DOT Optical Observations
  76. GRB 251025B: Swift-XRT confirmation of fading
  77. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  78. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  79. GRB 251023B: Swift-UVOT Upper Limits
  80. GRB 251027A: Swift-XRT observations
  81. GRB 251022A: SVOM/GRM observation
  82. GRB 251026B: Swift ToO observations
  83. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  84. GRB 251017A: INASAN-Kislovodsk optical observations
  85. GRB 251025B: Kilonova-Catcher optical afterglow detection
  86. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  87. GRB 251025C: AstroSat CZTI detection
  88. GRB 251026A: Swift-XRT observations
  89. GRB 251025B: OHP/T193 optical detection
  90. GRB 251025B: SVOM/VT optical bump
  91. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  92. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  93. GRB 251024A: Swift/UVOT Upper Limits
  94. GRB 251025B: Swift-XRT afterglow detection
  95. GRB 251024A: Swift-BAT refined analysis
  96. GRB 251024A: Swift-XRT refined Analysis
  97. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  98. GRB 251003A: VLA Detection
  99. GRB 251024A: Enhanced Swift-XRT position
  100. GRB 251023C: Glowbug gamma-ray detection

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