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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').
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"

15408 results found.

  1. GRB 250619B: Fermi GBM Observation
  2. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  3. GRB 250506A - SVOM/ECLAIRs Refined analysis
  4. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  5. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  6. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  7. GRB 250617B: Swift/UVOT Detection
  8. GRB 250617B: Kilonova-Catcher optical afterglow detection
  9. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  10. GRB 250617B: COLIBRÍ optical observations
  11. GRB 250617B: NOT NIR observations of the afterglow
  12. GRB 250617B: Fermi GBM Observation
  13. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  14. Konus-Wind detection of GRB 250615A / EP250615a
  15. GRB 250615A / EP250615a: AstroSat CZTI detection
  16. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  17. GRB 250615A: COLIBRÍ optical upper limit
  18. GRB 250615A: DDOTI Optical Upper Limit
  19. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  20. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  21. sb25061207: Mephisto optical upper limits
  22. IceCube alert 141029_8144692 retraction
  23. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  24. GRB 250612B: Fermi GBM Observation
  25. GRB 250612C: Fermi GBM Observation
  26. sb25061218: SVOM detection of a X-ray transient
  27. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  28. EP250610a: Upper limit from Fermi-GBM Observations
  29. sb25061207: SVOM detection of a X-ray transient
  30. GRB 250610B - SVOM/ECLAIRs refined analysis
  31. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  32. GRB 250610B: additional Liverpool Telescope optical observations
  33. GRB 250610B: SVOM/GRM analysis
  34. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  35. GRB 250610B: SVOM detection of a long burst
  36. GRB 250609A: Fermi GBM Observation
  37. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  38. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  39. GRB 250607A: SVOM/GRM observation of a long burst
  40. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  41. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  42. GRB 250605A: SVOM/VT optical upper limit
  43. EP/WXT 01709177873: GOTO observations confirm stellar variability
  44. GRB 250602A: GECAM detection
  45. GRB 250605A: LT optical observations
  46. Konus-Wind detection of GRB 250601A
  47. GRB 250601A: PRIME H band upper limit.
  48. GRB 250530A: SVOM/GRM analysis
  49. GRB 250601A: PRIME J band upper limit.
  50. GRB 250601A: VLT/FORS2 Optical Observation
  51. GRB 250601A: Fermi GBM Observation
  52. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  53. GRB 250602A: Fermi GBM Observation
  54. GRB 250602A: Fermi-LAT detection
  55. GRB 250521C: NOT spectroscopic observations exclude the afterglow candidate AT2025mgj
  56. GRB 250601A: Swift/XRT candidate afterglow
  57. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  58. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  59. GRB 250601A: Swift ToO observations
  60. GRB 250530A: VLT/HAWK-I NIR counterpart fading
  61. GRB 250530C: BOOTES-7 optical upper limit
  62. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  63. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  64. GRB 250521C/AT2025mgj: NOT optical observations of the afterglow candidate
  65. GRB 250530A: SVOM/VT optical upper limit
  66. GRB 250530A: SVOM detection of a burst
  67. EP-WXT trigger 01709177124: confirmation of a stellar flare by BOOTES-6
  68. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  69. GRB 250527C: Swift ToO observations
  70. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  71. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  72. GRB 250527B: Tiled Swift observations
  73. GRB 250520A: Gemini-South optical afterglow detection
  74. GRB 250314A: CIDER NB1008 upper limit
  75. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  76. EP-WXT trigger 01709176712: GOTO observations confirm stellar counterpart variability
  77. GRB 250521A: GRBAlpha detection
  78. GRB 250520A: GRBAlpha detection
  79. GRB 250521B: SVOM/VT optical upper limit
  80. GRB 250521D: SVOM/VT optical observations
  81. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  82. GRB 250521D: LAST tentative optical counterpart candidate
  83. GRB 250520A: 10 GHz VLA radio source
  84. GRB 250521B: Swift ToO observations
  85. GRB 250521B: SVOM detection of a burst through offline search
  86. Konus-Wind detection of GRB 250520A (short/hard)
  87. GRB 250520A: VLT/FORS2 Optical Observation
  88. GRB 250502A: Tautenburg observations
  89. Konus-Wind detection of GRB 250516B
  90. GRB 250520A: Gemini-South optical observations
  91. GRB 250520A: COLIBRÍ optical upper limit
  92. GRB 250520A: DDOTI Optical Upper Limit
  93. GRB 250520A: AstroSat CZTI detection of a short burst
  94. GRB 250516B: GRBAlpha detection
  95. GRB 250520A: SVOM/GRM observation
  96. GRB 250516B: Insight-HXMT detection
  97. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  98. Konus-Wind detection of GRB 250516A
  99. GRB 250516B: NuSTAR Detection of the Prompt Emission
  100. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317

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