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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

21921 results found.

  1. GRB 251203B: LCO optical upper limits
  2. GRB 251203B: SVOM/VT optical observation
  3. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  4. GRB 251203B: SVOM detection of a burst
  5. EP251130a: MAO/AZT-22 optical observations
  6. EP251202a / GRB251202A: AstroSat CZTI detection
  7. EP251202a/GRB 251202A: KAIT optical observations
  8. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  9. IPN triangulation of GRB 251129B (short/hard)
  10. GRB251129A/EP251129a: Swift UVOT detection
  11. GRB 251202A: Swift/UVOT Detection
  12. GRB 251201B: Kilonova-Catcher optical afterglow detection
  13. GRB 251201B: Swift/UVOT Detection
  14. GRB 251201B: GECAM-B observation of a long burst
  15. EP251130a: continued NOT optical observations indicate steep fading phase
  16. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  17. GRB 251126A: SAO RAS optical marginal detection
  18. GRB 251202A: Swift-XRT afterglow detection
  19. EP251129a/GRB 251129A: NOWT Detection
  20. GRB 251126A: SVOM/VT optical observation
  21. EP251130a: SVOM/VT optical observation
  22. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  23. GRB 251201A: SVOM/GRM observation of a burst
  24. GRB 251201B: SVOM/VT optical fading
  25. Swift GRB 251201B : MASTER optical counterpart detection
  26. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  27. GRB 251201B: Enhanced Swift-XRT position
  28. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  29. GRB 251130B: AstroSat CZTI detection
  30. GRB 251201B: Swift detection of a burst with an optical counterpart
  31. EP251130a: Mondy optical observations
  32. EP251130a: Optical detections with Kinder observations
  33. EP251130a: SAO RAS optical observations
  34. EP251130A: Optical observation from 1.3m DFOT
  35. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  36. EP251130a: JinShan optical observations
  37. GRB 251127A: SVOM/GRM observation
  38. EP251130a: COLIBRÍ optical counterpart candidate
  39. EP251130a: Einstein Probe detection of an X-ray transient
  40. GRB 251128A: AstroSat CZTI detection
  41. GRB 251129A / EP251129a: SAO RAS optical observations
  42. GRB 251126A: SAO RAS optical observations
  43. GRB 251128A: SVOM/GRM observation of a long burst
  44. SVOM GRB 251129A : MASTER optical counterpart detection
  45. GRB 251129A: Swift-XRT afterglow detection
  46. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  47. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  48. GRB 251129A: SVOM detection of a burst
  49. GRB 251129A: SVOM detection of a burst
  50. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  51. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  52. GRB 251126A: further SAO RAS optical observations
  53. GRB 251126A NUTTelA-TAO Early Measurements
  54. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  55. GRB251126A: MAO/AZT-22 optical observations
  56. GRB251126A: Continued optical observation from 1.3m DFOT
  57. GRB 251126A: Swift/UVOT Detection
  58. GRB 251126A: Mondy and SAO RAS optical observations
  59. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  60. GRB 251126A: 1.3m DFOT optical afterglow detection
  61. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  62. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  63. GRB 251126A: Enhanced Swift-XRT position
  64. GRB 251126A: Kilonova-Catcher optical afterglow detection
  65. GRB 251126A: Nanshan/HMT optical afterglow detection
  66. GRB 251121A: Fermi GBM Observation
  67. GRB 251126A: GIT discovery of the likely optical afterglow
  68. GRB 251126A: Swift detection of a burst
  69. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  70. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  71. EP251124b: NOT r- and z-band optical upper limits
  72. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  73. EP251124b: EP-WXT detection of a fast X-ray transient
  74. EP251124a: Xinglong GWAC-F60A optical observation
  75. EP251124a: NOT r- and z-band optical upper limits
  76. EP251124a: Swift-XRT observations
  77. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  78. EP251124a: Optical upper limit with Kinder observations
  79. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  80. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  81. EP251124a: GROWTH-India Telescope optical upper limits
  82. EP251124a: Einstein Probe detection of an X-ray transient
  83. GRB 251116C: Swift-XRT confirmation of fading
  84. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  85. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  86. EP251118A: 3.6m DOT optical afterglow detection
  87. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  88. GRB 251122A / EP251122a: WFST optical observations
  89. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  90. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  91. GRB 251122A / EP251122a: LCO optical upper limits
  92. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  93. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  94. GRB 251122A / EP251122a: SVOM detection of a long burst
  95. EP251122a: Einstein Probe detection of an X-ray transient
  96. EP251118a: Continued Optical Detection with Kinder observations
  97. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  98. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  99. EP251118a: Xinglong-2.16m optical observation
  100. EP251118A: 1.3m DFOT optical afterglow detection

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