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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"

15985 results found.

  1. GRB 251103A: SVOM detection of a bright burst
  2. GRB 251025C: SVOM/GRM observation
  3. GRB 251028A: SVOM/GRM observation
  4. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  5. GRB 251026B: LBT near-infrared observations
  6. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  7. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  8. GRB251026B: PRIME H-band upper limit
  9. GRB251025B: 3.6m DOT Optical Observations
  10. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  11. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  12. GRB 251023B: Swift-UVOT Upper Limits
  13. EP251027.145: COLIBRÍ optical upper limits
  14. GRB 251022A: SVOM/GRM observation
  15. GRB 251027A: LCO optical upper limit
  16. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  18. GRB 251023B / EP251023b: Mondy optical upper limit
  19. GRB 251017A: INASAN-Kislovodsk optical observations
  20. GRB 251026A: Mondy optical upper limit
  21. GRB 251025B: Mondy optical observations
  22. GRB 251025B: Kilonova-Catcher optical afterglow detection
  23. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  24. GRB 251026B: Tentative GOTO optical counterpart candidate
  25. EP251023a: Mondy optical observations
  26. GRB 251025B: MAO/AZT-22 optical observations
  27. GRB 251025B: OHP/T193 optical detection
  28. GRB 251025B: J-band detection with WINTER
  29. IceCube-251025A: DDOTI Optical Upper Limit
  30. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 251025B: SVOM/VT optical bump
  32. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  33. GRB 251023A: SVOM/GRM observation
  34. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  35. GRB 251025B: GROWTH-India Telescope optical observations
  36. GRB 251024A: Swift/UVOT Upper Limits
  37. GRB 251025B: SVOM/VT optical observations with VHF data
  38. GRB 251025B: MASTER OT detection
  39. GRB 251025B: SVOM/C-GFT optical counterpart detection
  40. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  41. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  42. GRB 251025A: SVOM/VT VHF optical upper limit
  43. GRB 251024A: LCOGT Optical Afterglow Detection
  44. GRB 251022A: KAIT optical observations
  45. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  46. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  47. EP251023a: MAO/AZT-22 optical observations
  48. GRB 251023B: OHP/T193 optical observations
  49. EP251023a: OHP/T193 optical observations
  50. EP251023b/GRB 251023B: JinShan optical observation
  51. GRB 251022A: Swift-XRT detection of GOTO25iym
  52. GRB 251022A: GROWTH-India Telescope optical observations
  53. EP251023a: GROWTH-India Telescope optical observations
  54. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  55. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  56. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  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. EP251021b/GRB 251021A: SVOM/VT optical candidate
  65. EP251023a: NOT optical counterpart detection
  66. EP251023a: GSP Optical Counterpart Detection
  67. EP251023a: Einstein Probe detection of an X-ray transient
  68. EP/WXT 01709247295: GOTO optical afterglow candidate.
  69. GRB 251022A: GOTO optical counterpart detection
  70. EP251021b: BOOTES-7 optical upper limit
  71. GRB 251017A: COLIBRÍ optical observations of a late plateau
  72. IceCube-251018A: DDOTI Optical Upper Limit
  73. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  74. GRB 251016A: Swift/UVOT Detection
  75. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  76. GRB 251016A: VLT/FORS2 Optical Observation
  77. GRB 251018A: MASTER OT detection
  78. GRB 251018A: TRT optical afterglow detection
  79. GRB 251018A: Swift detection of a burst with an optical counterpart
  80. GRB 251017A: SVOM/VT optical observation
  81. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  82. GRB 251017A: J-band detection with WINTER
  83. GRB 251013C: Liverpool Telescope observations
  84. GRB 251013C: Leavitt Observatory optical photometry
  85. GRB 251017A: JinShan observations of the optical afterglow
  86. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  87. GRB 251017A: COLIBRÍ Early Afterglow Detection
  88. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  89. GRB 251017A: Swift detection of a burst with an optical counterpart
  90. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  91. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  92. GRB 251016A: BOOTES-6/DPRT optical upper limit
  93. GRB 251013C: VLA detection
  94. GRB 251016A: SVOM detection of a short burst
  95. GRB 251014B: PRIME J-band upper limit
  96. GRB 251013C: Kilonova-Catcher optical afterglow detection
  97. GRB 251013D: Swift/UVOT Observations
  98. GRB 251013C: Swift/UVOT Detection
  99. GRB 251014B: Swift/UVOT Upper Limits
  100. GRB 251014B: VLT/FORS2 Optical Observation

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