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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"

16159 results found.

  1. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  2. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  3. GRB251026B: PRIME H-band upper limit
  4. GRB251025B: 3.6m DOT Optical Observations
  5. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  6. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  7. GRB 251023B: Swift-UVOT Upper Limits
  8. EP251027.145: COLIBRÍ optical upper limits
  9. GRB 251022A: SVOM/GRM observation
  10. GRB 251027A: LCO optical upper limit
  11. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  12. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  13. GRB 251023B / EP251023b: Mondy optical upper limit
  14. GRB 251017A: INASAN-Kislovodsk optical observations
  15. GRB 251026A: Mondy optical upper limit
  16. GRB 251025B: Mondy optical observations
  17. GRB 251025B: Kilonova-Catcher optical afterglow detection
  18. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  19. GRB 251026B: Tentative GOTO optical counterpart candidate
  20. EP251023a: Mondy optical observations
  21. GRB 251025B: MAO/AZT-22 optical observations
  22. GRB 251025B: OHP/T193 optical detection
  23. GRB 251025B: J-band detection with WINTER
  24. IceCube-251025A: DDOTI Optical Upper Limit
  25. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  26. GRB 251025B: SVOM/VT optical bump
  27. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  28. GRB 251023A: SVOM/GRM observation
  29. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  30. GRB 251025B: GROWTH-India Telescope optical observations
  31. GRB 251024A: Swift/UVOT Upper Limits
  32. GRB 251025B: SVOM/VT optical observations with VHF data
  33. GRB 251025B: MASTER OT detection
  34. GRB 251025B: SVOM/C-GFT optical counterpart detection
  35. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  36. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. GRB 251025A: SVOM/VT VHF optical upper limit
  38. GRB 251024A: LCOGT Optical Afterglow Detection
  39. GRB 251022A: KAIT optical observations
  40. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  41. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  42. EP251023a: MAO/AZT-22 optical observations
  43. GRB 251023B: OHP/T193 optical observations
  44. EP251023a: OHP/T193 optical observations
  45. EP251023b/GRB 251023B: JinShan optical observation
  46. GRB 251022A: Swift-XRT detection of GOTO25iym
  47. GRB 251022A: GROWTH-India Telescope optical observations
  48. EP251023a: GROWTH-India Telescope optical observations
  49. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  50. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  51. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  52. EP251023a: COLIBRÍ optical observations
  53. GRB 251013C: further SAO RAS optical observations
  54. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  55. GRB 251022A: COLIBRÍ optical observations
  56. GRB 251013C: ISON-Castelgrande observatory optical observations
  57. GRB 251022A: MASTER OT detection
  58. GRB 251022A: DDOTI Optical Detection
  59. EP251021b/GRB 251021A: SVOM/VT optical candidate
  60. EP251023a: NOT optical counterpart detection
  61. EP251023a: GSP Optical Counterpart Detection
  62. EP251023a: Einstein Probe detection of an X-ray transient
  63. EP/WXT 01709247295: GOTO optical afterglow candidate.
  64. GRB 251022A: GOTO optical counterpart detection
  65. EP251021b: BOOTES-7 optical upper limit
  66. GRB 251017A: COLIBRÍ optical observations of a late plateau
  67. IceCube-251018A: DDOTI Optical Upper Limit
  68. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  69. GRB 251016A: Swift/UVOT Detection
  70. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  71. GRB 251016A: VLT/FORS2 Optical Observation
  72. GRB 251018A: MASTER OT detection
  73. GRB 251018A: TRT optical afterglow detection
  74. GRB 251018A: Swift detection of a burst with an optical counterpart
  75. GRB 251017A: SVOM/VT optical observation
  76. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  77. GRB 251017A: J-band detection with WINTER
  78. GRB 251013C: Liverpool Telescope observations
  79. GRB 251013C: Leavitt Observatory optical photometry
  80. GRB 251017A: JinShan observations of the optical afterglow
  81. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  82. GRB 251017A: COLIBRÍ Early Afterglow Detection
  83. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  84. GRB 251017A: Swift detection of a burst with an optical counterpart
  85. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  86. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  87. GRB 251016A: BOOTES-6/DPRT optical upper limit
  88. GRB 251013C: VLA detection
  89. GRB 251016A: SVOM detection of a short burst
  90. GRB 251014B: PRIME J-band upper limit
  91. GRB 251013C: Kilonova-Catcher optical afterglow detection
  92. GRB 251013D: Swift/UVOT Observations
  93. GRB 251013C: Swift/UVOT Detection
  94. GRB 251014B: Swift/UVOT Upper Limits
  95. GRB 251014B: VLT/FORS2 Optical Observation
  96. GRB 251014D: Swift/UVOT Upper Limits
  97. GRB 251014D: BOOTES-6/DPRT optical upper limit
  98. GRB 251013C: MAO/AZT-22 optical observations
  99. GRB 251011B: SVOM/VT optical upper limit
  100. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations

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