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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"

17462 results found.

  1. GRB 250625A: ABObservatory afterglow detection
  2. GRB 250625A: OHP/T193 optical detection
  3. GRB 250625A: COLIBRÍ optical observations
  4. GRB 250625A: JinShan optical observations
  5. GRB 250625A: SAO RAS possible optical afterglow
  6. GRB 250625A: Enhanced Swift-XRT position
  7. GRB 250625A: Swift detection of a burst
  8. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  9. GRB 250620A: AstroSat CZTI detection
  10. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  11. GRB 241018A: Maidanak optical observations
  12. IPN triangulation of GRB 250620С (long/bright)
  13. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  14. GRB 250620C: SVOM/GRM observation
  15. GRB 250620A: SVOM/GRM observation of a short burst
  16. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  17. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  18. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  19. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  20. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  21. GRB 250617B: Nickel telescope optical observations
  22. GRB 250615A: Kilonova-Catcher optical upper limits
  23. GRB 250617B: Assy AZT-20 Optical Observations
  24. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  25. GRB 250617B: Swift/UVOT Detection
  26. GRB 250617B: Kilonova-Catcher optical afterglow detection
  27. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  28. GRB 250617B: COLIBRÍ optical observations
  29. GRB 250617B: NOT NIR observations of the afterglow
  30. GRB 250617B: NUTTelA-TAO early time optical observations
  31. GRB 250617B: Enhanced Swift-XRT position
  32. The EP-WXT trigger 01709178990 is likely a flaring star
  33. GRB 250617B: SAO RAS optical observations
  34. GRB 250617B: Swift detection of a burst with an optical counterpart
  35. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  36. EP-WXT trigger 01709178975: GOTO optical upper limit
  37. GRB 250615A / EP250615a: AstroSat CZTI detection
  38. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  39. GRB 250615A: COLIBRÍ optical upper limit
  40. GRB 250615A: DDOTI Optical Upper Limit
  41. GRB 250615A: Swift/UVOT Upper Limits
  42. sb25061207/SVOM: T120 OHP optical upper limit
  43. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  44. GRB 250615A: Enhanced Swift-XRT position
  45. GRB 250615A: Swift detection of a burst
  46. sb25061207: Mephisto optical upper limits
  47. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  48. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  49. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  50. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  51. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  52. sb25061207: EP-FXT follow-up observation and afterglow candidate
  53. EP250612a: SVOM/VT optical candidate
  54. sb25061218: SVOM detection of a X-ray transient
  55. EP250612a/GRB 250612B: JinShan optical upper limit
  56. sb25061207: SVOM/VT optical counterpart
  57. GRB 250610B: Swift-XRT refined Analysis
  58. EP250612a: Einstein Probe detection of an X-ray transient
  59. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  60. sb25061207: SVOM detection of a X-ray transient
  61. GRB 250610B: Swift/UVOT Detection
  62. EP250610A: Swift/UVOT Upper limits
  63. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  64. EP250610a: TNG NIR upper limit
  65. GRB 250610B: REM optical/NIR observations
  66. EP250610a: Liverpool Telescope optical upper limits
  67. GRB 250610B: additional Liverpool Telescope optical observations
  68. GRB 250610B: SVOM/VT optical counterpart
  69. GRB 250610B: OHP/T120 optical counterpart candidate
  70. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  71. GRB 250610B: SVOM detection of a long burst
  72. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  73. EP250610a: SVOM/VT optical upper limit
  74. EP250610a: REM optical/NIR observations
  75. EP250610a: COLIBRÍ optical upper limit
  76. EP250610a: Einstein Probe detection of an X-ray transient
  77. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  78. GRB 250605A: Swift/UVOT Upper Limits
  79. GRB 250527C: CrAO Optical Upper Limit
  80. GRB 250607A: SVOM/GRM observation of a long burst
  81. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  82. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  83. The EP-WXT trigger 01709178069 is likely a flaring star
  84. GRB 250605A: Enhanced Swift-XRT position
  85. Fermi trigger No 770867684: Global MASTER-Net observations report
  86. GRB 250605A: Swift detection of a burst
  87. IPN triangulation of GRB 250404B
  88. IPN triangulation of GRB 250529A
  89. GRB 250601A: PRIME H band upper limit.
  90. GRB 250601A: PRIME J band upper limit.
  91. GRB 250601A: VLT/FORS2 Optical Observation
  92. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  93. GRB 250603A: Swift/UVOT Upper Limits
  94. GRB 250603A: Enhanced Swift-XRT position
  95. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  96. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  97. GRB 250602A: DDOTI Optical Upper Limit
  98. GRB 250601A: Swift ToO observations
  99. EP#01709177494: SVOM/VT optical observations
  100. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations

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