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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"

19806 results found.

  1. GRB 251202A: SVOM/GRM observation
  2. GRB 251203A: SVOM/GRM observation
  3. GRB 251203C: J-band observations with WINTER
  4. GRB 251203C: SVOM/VT optical counterpart
  5. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  6. GRB 251203B: Swift-XRT observations
  7. GRB 251203C: LCO optical upper limits
  8. GRB 251203B: LCO optical upper limits
  9. GRB 251203B: SVOM/VT optical observation
  10. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  11. GRB 251203B: SVOM detection of a burst
  12. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  13. EP251130a: MAO/AZT-22 optical observations
  14. EP251202a / GRB251202A: AstroSat CZTI detection
  15. GRB 251201B: Fermi GBM Observation
  16. EP251202a/GRB 251202A: KAIT optical observations
  17. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  18. IPN triangulation of GRB 251129B (short/hard)
  19. GRB251129A/EP251129a: Swift UVOT detection
  20. GRB 251202A: Swift/UVOT Detection
  21. GRB 251201B: Kilonova-Catcher optical afterglow detection
  22. GRB 251201B: Swift/UVOT Detection
  23. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  24. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  25. GRB 251126A: SAO RAS optical marginal detection
  26. GRB 251202A: Swift-XRT afterglow detection
  27. EP251129a/GRB 251129A: NOWT Detection
  28. GRB 251126A: SVOM/VT optical observation
  29. EP251130a: SVOM/VT optical observation
  30. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  31. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  32. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 251201A: SVOM/GRM observation of a burst
  34. GRB 251201B: SVOM/VT optical fading
  35. Swift GRB 251201B : MASTER optical counterpart detection
  36. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  37. GRB 251201B: Enhanced Swift-XRT position
  38. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  39. GRB 251130B: AstroSat CZTI detection
  40. GRB 251201B: Swift detection of a burst with an optical counterpart
  41. EP251130a: Mondy optical observations
  42. EP251130a: Optical detections with Kinder observations
  43. EP251130a: SAO RAS optical observations
  44. EP251130A: Optical observation from 1.3m DFOT
  45. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  46. EP251130a: JinShan optical observations
  47. GRB 251127A: SVOM/GRM observation
  48. EP251130a: COLIBRÍ optical counterpart candidate
  49. EP251130a: Einstein Probe detection of an X-ray transient
  50. GRB 251129A / EP251129a: SAO RAS optical observations
  51. GRB 251126A: SAO RAS optical observations
  52. GRB 251128A: GECAM-B detection
  53. GRB 251128A: SVOM/GRM observation of a long burst
  54. SVOM GRB 251129A : MASTER optical counterpart detection
  55. GRB 251129A: Swift-XRT afterglow detection
  56. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  57. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  58. GRB 251129A: SVOM detection of a burst
  59. GRB 251129A: SVOM detection of a burst
  60. GRB 251126A: Swift-BAT refined analysis
  61. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  62. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  63. GRB 251126A: further SAO RAS optical observations
  64. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  65. GRB251126A: MAO/AZT-22 optical observations
  66. GRB251126A: Continued optical observation from 1.3m DFOT
  67. GRB 251126A: Swift/UVOT Detection
  68. EP251124a: Pan-STARRS ri-band imaging and photometry
  69. GRB 251126A: Mondy and SAO RAS optical observations
  70. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  71. GRB 251126A: 1.3m DFOT optical afterglow detection
  72. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  73. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  74. GRB 251126A: Enhanced Swift-XRT position
  75. GRB 251126A: Kilonova-Catcher optical afterglow detection
  76. GRB 251126A: Nanshan/HMT optical afterglow detection
  77. GRB 251126A: GIT discovery of the likely optical afterglow
  78. GRB 251126A: Swift detection of a burst
  79. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  80. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  81. EP251124b: NOT r- and z-band optical upper limits
  82. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  83. EP251124b: EP-WXT detection of a fast X-ray transient
  84. EP251124a: Xinglong GWAC-F60A optical observation
  85. EP251124a: NOT r- and z-band optical upper limits
  86. EP251124a: Swift-XRT observations
  87. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  88. EP251124a: Optical upper limit with Kinder observations
  89. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  90. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  91. EP251124a: GROWTH-India Telescope optical upper limits
  92. EP251124a: Einstein Probe detection of an X-ray transient
  93. GRB 251116C: Swift-XRT confirmation of fading
  94. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  95. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  96. EP251118A: 3.6m DOT optical afterglow detection
  97. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  98. GRB 251122A / EP251122a: WFST optical observations
  99. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  100. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit

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