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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').
Advanced Search

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"

18291 results found.

  1. EP251202a/GRB 251202A: KAIT optical observations
  2. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  3. IPN triangulation of GRB 251129B (short/hard)
  4. GRB251129A/EP251129a: Swift UVOT detection
  5. GRB 251202A: Swift/UVOT Detection
  6. GRB 251201B: Kilonova-Catcher optical afterglow detection
  7. GRB 251201B: Swift/UVOT Detection
  8. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  9. GRB 251126A: SAO RAS optical marginal detection
  10. GRB 251202A: Swift-XRT afterglow detection
  11. EP251129a/GRB 251129A: NOWT Detection
  12. GRB 251126A: SVOM/VT optical observation
  13. EP251130a: SVOM/VT optical observation
  14. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  15. GRB 251201A: SVOM/GRM observation of a burst
  16. GRB 251201B: SVOM/VT optical fading
  17. Swift GRB 251201B : MASTER optical counterpart detection
  18. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  19. GRB 251201B: Enhanced Swift-XRT position
  20. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  21. GRB 251130B: AstroSat CZTI detection
  22. GRB 251201B: Swift detection of a burst with an optical counterpart
  23. EP251130a: Mondy optical observations
  24. EP251130a: Optical detections with Kinder observations
  25. EP251130a: SAO RAS optical observations
  26. EP251130A: Optical observation from 1.3m DFOT
  27. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  28. EP251130a: JinShan optical observations
  29. GRB 251127A: SVOM/GRM observation
  30. EP251130a: COLIBRÍ optical counterpart candidate
  31. EP251130a: Einstein Probe detection of an X-ray transient
  32. GRB 251129A / EP251129a: SAO RAS optical observations
  33. GRB 251126A: SAO RAS optical observations
  34. GRB 251128A: SVOM/GRM observation of a long burst
  35. SVOM GRB 251129A : MASTER optical counterpart detection
  36. GRB 251129A: Swift-XRT afterglow detection
  37. GRB 251129A: Swift ToO observations
  38. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  39. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  40. GRB 251129A: SVOM detection of a burst
  41. GRB 251129A: SVOM detection of a burst
  42. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  43. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  44. GRB 251126A: further SAO RAS optical observations
  45. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  46. GRB251126A: MAO/AZT-22 optical observations
  47. GRB251126A: Continued optical observation from 1.3m DFOT
  48. GRB 251126A: Swift/UVOT Detection
  49. GRB 251126A: Mondy and SAO RAS optical observations
  50. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  51. GRB 251126A: 1.3m DFOT optical afterglow detection
  52. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  53. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  54. GRB 251126A: Enhanced Swift-XRT position
  55. GRB 251126A: Kilonova-Catcher optical afterglow detection
  56. GRB 251126A: Nanshan/HMT optical afterglow detection
  57. GRB 251126A: GIT discovery of the likely optical afterglow
  58. GRB 251126A: Swift detection of a burst
  59. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  60. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  61. EP251124b: NOT r- and z-band optical upper limits
  62. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  63. EP251124b: EP-WXT detection of a fast X-ray transient
  64. EP251124a: Xinglong GWAC-F60A optical observation
  65. EP251124a: NOT r- and z-band optical upper limits
  66. EP251124a: Swift-XRT observations
  67. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  68. EP251124a: Optical upper limit with Kinder observations
  69. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  70. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  71. EP251124a: GROWTH-India Telescope optical upper limits
  72. EP251124a: Einstein Probe detection of an X-ray transient
  73. GRB 251116C: Swift-XRT confirmation of fading
  74. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  75. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  76. EP251118A: 3.6m DOT optical afterglow detection
  77. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  78. GRB 251122A / EP251122a: WFST optical observations
  79. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  80. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  81. GRB 251122A / EP251122a: LCO optical upper limits
  82. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  83. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  84. GRB 251122A / EP251122a: SVOM detection of a long burst
  85. EP251122a: Einstein Probe detection of an X-ray transient
  86. EP251118a: Continued Optical Detection with Kinder observations
  87. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  88. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  89. EP251118a: Xinglong-2.16m optical observation
  90. Fermi trigger No 785388351: Global MASTER-Net observations report
  91. EP251118A: 1.3m DFOT optical afterglow detection
  92. GRB 251118A: Swift/UVOT Detection
  93. EP251118a / GRB 251118C: SAO RAS optical observations
  94. GRB 251118A: Swift-XRT afterglow detection
  95. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  96. EP251118a: Optical detection with Kinder observations
  97. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  98. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  99. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  100. GRB 251117A: Swift-XRT observations

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