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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"

19552 results found.

  1. GRB 241018A: Maidanak optical observations
  2. IPN triangulation of GRB 250620C (long/bright)
  3. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  4. GRB 250620C: SVOM/GRM observation
  5. GRB 250620A: SVOM/GRM observation of a short burst
  6. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  7. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  8. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  9. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  10. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  11. GRB 250617B: Nickel telescope optical observations
  12. GRB 250615A: Kilonova-Catcher optical upper limits
  13. GRB 250617B: Assy AZT-20 Optical Observations
  14. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  15. GRB 250617B: Swift/UVOT Detection
  16. GRB 250617B: Kilonova-Catcher optical afterglow detection
  17. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  18. GRB 250617B: COLIBRÍ optical observations
  19. GRB 250617B: NOT NIR observations of the afterglow
  20. GRB 250617B: NUTTelA-TAO early time optical observations
  21. GRB 250617B: Enhanced Swift-XRT position
  22. The EP-WXT trigger 01709178990 is likely a flaring star
  23. GRB 250617B: SAO RAS optical observations
  24. GRB 250617B: Swift detection of a burst with an optical counterpart
  25. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  26. EP-WXT trigger 01709178975: GOTO optical upper limit
  27. GRB 250615A / EP250615a: AstroSat CZTI detection
  28. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  29. GRB 250615A: COLIBRÍ optical upper limit
  30. GRB 250615A: DDOTI Optical Upper Limit
  31. GRB 250615A: Swift/UVOT Upper Limits
  32. sb25061207/SVOM: T120 OHP optical upper limit
  33. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  34. GRB 250615A: Enhanced Swift-XRT position
  35. GRB 250615A: Swift detection of a burst
  36. sb25061207: Mephisto optical upper limits
  37. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  38. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  39. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  40. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  41. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  42. sb25061207: EP-FXT follow-up observation and afterglow candidate
  43. EP250612a: SVOM/VT optical candidate
  44. sb25061218: SVOM detection of a X-ray transient
  45. EP250612a/GRB 250612B: JinShan optical upper limit
  46. sb25061207: SVOM/VT optical counterpart
  47. GRB 250610B: Swift-XRT refined Analysis
  48. EP250612a: Einstein Probe detection of an X-ray transient
  49. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  50. sb25061207: SVOM detection of a X-ray transient
  51. GRB 250610B: Swift/UVOT Detection
  52. EP250610A: Swift/UVOT Upper limits
  53. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  54. EP250610a: TNG NIR upper limit
  55. GRB 250610B: REM optical/NIR observations
  56. EP250610a: Liverpool Telescope optical upper limits
  57. GRB 250610B: additional Liverpool Telescope optical observations
  58. GRB 250610B: SVOM/VT optical counterpart
  59. GRB 250610B: OHP/T120 optical counterpart candidate
  60. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  61. GRB 250610B: SVOM detection of a long burst
  62. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  63. EP250610a: SVOM/VT optical upper limit
  64. EP250610a: REM optical/NIR observations
  65. EP250610a: COLIBRÍ optical upper limit
  66. EP250610a: Einstein Probe detection of an X-ray transient
  67. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  68. GRB 250605A: Swift/UVOT Upper Limits
  69. GRB 250527C: CrAO Optical Upper Limit
  70. GRB 250607A: SVOM/GRM observation of a long burst
  71. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  72. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  73. The EP-WXT trigger 01709178069 is likely a flaring star
  74. GRB 250605A: Enhanced Swift-XRT position
  75. Fermi trigger No 770867684: Global MASTER-Net observations report
  76. GRB 250605A: Swift detection of a burst
  77. IPN triangulation of GRB 250404B
  78. IPN triangulation of GRB 250529A
  79. GRB 250601A: PRIME H band upper limit.
  80. GRB 250601A: PRIME J band upper limit.
  81. GRB 250601A: VLT/FORS2 Optical Observation
  82. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  83. GRB 250603A: Swift/UVOT Upper Limits
  84. GRB 250603A: Enhanced Swift-XRT position
  85. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  86. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  87. GRB 250602A: DDOTI Optical Upper Limit
  88. GRB 250601A: Swift ToO observations
  89. EP#01709177494: SVOM/VT optical observations
  90. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  91. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  92. GRB 250530C: Enhanced Swift-XRT position
  93. GRB 250530C: Swift detection of a burst
  94. GRB 250521C/AT2025mgj: NOT optical observations of the afterglow candidate
  95. GRB 250530A: SVOM/VT optical upper limit
  96. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  97. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  98. GRB 250530A: SVOM detection of a burst
  99. GRB 250527C: Swift/UVOT Upper Limits
  100. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst

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