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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"

21793 results found.

  1. GRB 251205A: COLIBRÍ optical observations
  2. GRB 251205A: GOTO optical afterglow detection
  3. GRB 251205A: NOT optical observations
  4. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  5. Swift GRB 251205A : MASTER OT detection with host galaxy
  6. Swift GRB251205A: Global MASTER-Net observations report
  7. GRB 251203C: SVOM/ECLAIRs refined analysis
  8. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  9. GRB 251203C: J-band observations with WINTER
  10. EP251130a: JinShan near-infrared observations
  11. GRB 251203C: SVOM/VT optical counterpart
  12. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  13. GRB 251203B: Swift-XRT observations
  14. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  15. GRB 251203B: LCO optical upper limits
  16. GRB 251203B: SVOM/VT optical observation
  17. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  18. SVOM GRB251203.77: Global MASTER-Net observations report
  19. SVOM GRB251203B: Global MASTER-Net observations report
  20. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  21. EP251130a: MAO/AZT-22 optical observations
  22. GRB 251202A / EP251202a: SVOM/VT optical observation
  23. EP251202a/GRB 251202A: KAIT optical observations
  24. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  25. Fermi GRB 251202B: Global MASTER-Net observations report
  26. GRB251129A/EP251129a: Swift UVOT detection
  27. GRB 251202A: Swift/UVOT Detection
  28. GRB 251201B: Kilonova-Catcher optical afterglow detection
  29. GRB 251201B: Swift/UVOT Detection
  30. EP251130a: continued NOT optical observations indicate steep fading phase
  31. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  32. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  33. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  34. GRB 251202A: GOTO optical afterglow detection
  35. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  36. GRB 251202A: Swift-XRT afterglow detection
  37. Fermi GRB 251202A: Global MASTER-Net observations report
  38. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  39. Swift GRB 251201B: Global MASTER-Net observations report
  40. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  41. EP251130a: Mondy optical observations
  42. EP251130a: Optical detections with Kinder observations
  43. SVOM GRB251201.19: Global MASTER-Net observations report
  44. EP251130a: SAO RAS optical observations
  45. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  46. EP251130a: KAIT optical observations
  47. EP251130A: Optical observation from 1.3m DFOT
  48. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  49. EP251130a: JinShan optical observations
  50. Fermi GRB 251130B: Global MASTER-Net observations report
  51. IceCube Alert 251130.75: Global MASTER-Net observations report
  52. EP251130a: Swift-XRT counterpart detection
  53. EP251130a: Global MASTER-Net observations report
  54. EP251129a/GRB 251129A: EP-FXT follow-up observations
  55. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  56. GRB 251129A / EP251129a: SAO RAS optical observations
  57. GRB 251126A: SAO RAS optical observations
  58. GRB 251129A: Swift-XRT afterglow detection
  59. GRB 251129A: Swift ToO observations
  60. EP251129a: Global MASTER-Net observations report
  61. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  62. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  63. SVOM GRB251129A: Global MASTER-Net observations report
  64. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  65. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  66. Fermi GRB 251128A: Global MASTER-Net observations report
  67. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  68. GRB 251126A: further SAO RAS optical observations
  69. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  70. GRB 251126A NUTTelA-TAO Early Measurements
  71. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  72. GRB251126A: MAO/AZT-22 optical observations
  73. GRB251126A: Continued optical observation from 1.3m DFOT
  74. GRB 251126A: Swift/UVOT Detection
  75. GRB 251126A: Mondy and SAO RAS optical observations
  76. GRB 251126A: NOT optical observations
  77. GRB 251126A: 1.3m DFOT optical afterglow detection
  78. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  79. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  80. Fermi GRB 251127A: Global MASTER-Net observations report
  81. GRB 251126A: Kilonova-Catcher optical afterglow detection
  82. GRB 251126A: Asiago i-band detection
  83. GRB 251126A: Nanshan/HMT optical afterglow detection
  84. Swift GRB 251126A: Global MASTER-Net observations report
  85. GRB 251126A: GIT discovery of the likely optical afterglow
  86. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  87. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  88. EP251124b: NOT r- and z-band optical upper limits
  89. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  90. Fermi GRB 251125B: Global MASTER-Net observations report
  91. EP251124b: Global MASTER-Net observations report
  92. Fermi GRB 251125A: Global MASTER-Net observations report
  93. EP251124a: NOT r- and z-band optical upper limits
  94. EP251124a: Global MASTER-Net observations report
  95. EP251124a: Swift-XRT observations
  96. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  97. EP251124a: Optical upper limit with Kinder observations
  98. EP251118A: 6 GHz VLA Detection
  99. Fermi GRB 251124a: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901

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