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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

23413 results found.

  1. GRB 251025B: OHP/T193 optical upper limit
  2. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  3. GRB 251103A: LCO optical observation
  4. EP251102.890: COLIBRÍ optical counterpart candidate
  5. GRB 251103A: GOTO optical afterglow detection
  6. GRB 251102A: AstroSat CZTI detection
  7. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  8. GRB 251103A: BOOTES-2/TELMA optical afterglow
  9. GRB 251103A: LCO optical afterglow detection
  10. GRB 251103A: NOT optical afterglow candidate
  11. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  12. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  13. GRB 251025C: SVOM/GRM observation
  14. GRB 251028A: SVOM/GRM observation
  15. GRB 251022A: Swift-XRT confirmation of fading
  16. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  17. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  18. GRB 251028B: Glowbug gamma-ray detection
  19. GRB 251028A: Glowbug gamma-ray detection
  20. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  21. GRB251026B: PRIME H-band upper limit
  22. GRB251025B: 3.6m DOT Optical Observations
  23. SVOM trigger sb25102702/GRB 251027A is not a GRB
  24. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  25. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  26. GRB 251025C: Glowbug gamma-ray detection
  27. GRB 251023B: Swift-UVOT Upper Limits
  28. GRB 251027A: Swift-XRT observations
  29. EP251027.145: COLIBRÍ optical upper limits
  30. GRB 251022A: SVOM/GRM observation
  31. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  32. GRB 251027A: LCO optical upper limit
  33. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  34. GRB 251023B / EP251023b: Mondy optical upper limit
  35. GRB 251017A: INASAN-Kislovodsk optical observations
  36. GRB 251026A: Mondy optical upper limit
  37. GRB 251025B: Mondy optical observations
  38. GRB 251025B: Kilonova-Catcher optical afterglow detection
  39. Konus-Wind detection of GRB 251016A (short/hard)
  40. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  41. GRB 251026B: Tentative GOTO optical counterpart candidate
  42. EP251023a: Mondy optical observations
  43. GRB 251025B: MAO/AZT-22 optical observations
  44. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  45. GRB 251026A: Swift-XRT observations
  46. GRB 251025B: OHP/T193 optical detection
  47. GRB 251025B: J-band detection with WINTER
  48. GRB 251026A: SVOM/C-GFT upper limit
  49. IceCube-251025A: DDOTI Optical Upper Limit
  50. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  51. GRB 251026A: SVOM detection of a long burst
  52. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  53. GRB 251023A: SVOM/GRM observation
  54. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  55. GRB 251025B: GROWTH-India Telescope optical observations
  56. GRB 251024A: Swift/UVOT Upper Limits
  57. GRB 251025B: Swift-XRT afterglow detection
  58. GRB 251024A: Swift-BAT refined analysis
  59. GRB 251025A (sb25102501): stellar flare confirmed
  60. GRB 251025B: SVOM/VT optical observations with VHF data
  61. GRB 251025B: MASTER OT detection
  62. GRB 251025B: SVOM/C-GFT optical counterpart detection
  63. GRB 251025B: SVOM detection of a burst
  64. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  65. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB 251025A: SVOM/VT VHF optical upper limit
  67. GRB 251025A: SVOM detection of a faint burst
  68. GRB 251024A: Enhanced Swift-XRT position
  69. GRB 251023C: Glowbug gamma-ray detection
  70. GRB 251024A: LCOGT Optical Afterglow Detection
  71. GRB 251022A: KAIT optical observations
  72. GRB 251024A: Swift detection of a burst
  73. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  74. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  75. EP251023a: MAO/AZT-22 optical observations
  76. GRB 251023B: OHP/T193 optical observations
  77. EP251023b/GRB 251023B: JinShan optical observation
  78. GRB 251022A: Swift-XRT detection of GOTO25iym
  79. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  80. GRB 251022A: GROWTH-India Telescope optical observations
  81. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  82. EP251023a: GROWTH-India Telescope optical observations
  83. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  84. GRB 251023A: Glowbug gamma-ray detection
  85. GRB 251023B: Glowbug gamma-ray detection
  86. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  87. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  88. IPN triangulation of GRB 251016B
  89. EP#01709247298: Swift-XRT counterpart detection
  90. EP251023a: COLIBRÍ optical observations
  91. GRB 251013C: further SAO RAS optical observations
  92. GRB 251022A: COLIBRÍ optical observations
  93. GRB 251013C: ISON-Castelgrande observatory optical observations
  94. GRB 251022A: MASTER OT detection
  95. GRB 251022A: DDOTI Optical Detection
  96. EP251021b/GRB 251021A: SVOM/VT optical candidate
  97. EP251023a: NOT optical counterpart detection
  98. EP251023a: Einstein Probe detection of an X-ray transient
  99. EP251021b: Einstein Probe detection of a fast X-ray transient
  100. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate

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