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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"

17851 results found.

  1. GRB 251205A: Liverpool Telescope further optical follow-up observations
  2. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  3. The EP-WXT trigger 01709249380 is likely a flaring star
  4. GRB 251205A: GROWTH-India Telescope optical observations
  5. GRB 251205A: Swift-BAT refined analysis
  6. GRB 251205A: Swift-XRT refined Analysis
  7. GRB 251205A: Swift/UVOT Detection
  8. GRB 251205A: Liverpool Telescope optical follow-up observations
  9. GRB 251203C: Swift/UVOT Upper Limit
  10. GRB 251205A: COLIBRÍ optical observations
  11. GRB 251205A: NOT optical observations
  12. GRB 251205A: Enhanced Swift-XRT position
  13. Swift GRB 251205A : MASTER OT detection with host galaxy
  14. GRB 251205A: Swift detection of a burst with an optical afterglow
  15. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  16. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. GRB 251202A: SVOM/GRM observation
  18. GRB 251203A: SVOM/GRM observation
  19. GRB 251203C: J-band observations with WINTER
  20. GRB 251203C: SVOM/VT optical counterpart
  21. GRB 251203C: EP-FXT follow-up observation
  22. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  23. GRB 251203C: LCO optical upper limits
  24. GRB 251203B: LCO optical upper limits
  25. GRB 251203B: SVOM/VT optical observation
  26. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  27. GRB 251203B: SVOM detection of a burst
  28. EP251130a: MAO/AZT-22 optical observations
  29. EP251202a/GRB 251202A: KAIT optical observations
  30. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  31. IPN triangulation of GRB 251129B (short/hard)
  32. GRB251129A/EP251129a: Swift UVOT detection
  33. GRB 251202A: Swift/UVOT Detection
  34. GRB 251201B: Kilonova-Catcher optical afterglow detection
  35. GRB 251201B: Swift/UVOT Detection
  36. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  37. GRB 251126A: SAO RAS optical marginal detection
  38. GRB 251202A: Swift-XRT afterglow detection
  39. EP251129a/GRB 251129A: NOWT Detection
  40. GRB 251126A: SVOM/VT optical observation
  41. EP251130a: SVOM/VT optical observation
  42. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  43. GRB 251201A: SVOM/GRM observation of a burst
  44. GRB 251201B: SVOM/VT optical fading
  45. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  46. GRB 251201B: Enhanced Swift-XRT position
  47. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  48. GRB 251201B: Swift detection of a burst with an optical counterpart
  49. EP251130a: Mondy optical observations
  50. EP251130a: Optical detections with Kinder observations
  51. EP251130a: SAO RAS optical observations
  52. EP251130A: Optical observation from 1.3m DFOT
  53. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  54. EP251130a: JinShan optical observations
  55. GRB 251127A: SVOM/GRM observation
  56. EP251130a: COLIBRÍ optical counterpart candidate
  57. EP251130a: Einstein Probe detection of an X-ray transient
  58. EP251129a/GRB 251129A: EP-FXT follow-up observations
  59. GRB 251129A / EP251129a: SAO RAS optical observations
  60. GRB 251126A: SAO RAS optical observations
  61. GRB 251128A: SVOM/GRM observation of a long burst
  62. SVOM GRB 251129A : MASTER optical counterpart detection
  63. GRB 251129A: Swift-XRT afterglow detection
  64. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  65. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  66. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  67. GRB 251129A: SVOM detection of a burst
  68. SVOM GRB251129A: Global MASTER-Net observations report
  69. GRB 251129A: SVOM detection of a burst
  70. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  71. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  72. GRB 251126A: further SAO RAS optical observations
  73. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  74. GRB251126A: MAO/AZT-22 optical observations
  75. GRB251126A: Continued optical observation from 1.3m DFOT
  76. GRB 251126A: Swift/UVOT Detection
  77. GRB 251126A: Mondy and SAO RAS optical observations
  78. GRB 251126A: Swift-XRT refined Analysis
  79. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  80. GRB 251126A: 1.3m DFOT optical afterglow detection
  81. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  82. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  83. GRB 251126A: Enhanced Swift-XRT position
  84. GRB 251126A: Kilonova-Catcher optical afterglow detection
  85. GRB 251126A: Nanshan/HMT optical afterglow detection
  86. GRB 251126A: GIT discovery of the likely optical afterglow
  87. GRB 251126A: Swift detection of a burst
  88. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  89. EP251124b follow-up observation by EP-FXT
  90. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  91. EP251124b: NOT r- and z-band optical upper limits
  92. EP251124b: EP-WXT detection of a fast X-ray transient
  93. EP251124a: Xinglong GWAC-F60A optical observation
  94. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  95. EP251124a: NOT r- and z-band optical upper limits
  96. EP251124a: Swift-XRT observations
  97. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  98. EP251124a: Optical upper limit with Kinder observations
  99. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  100. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901

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