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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"

17373 results found.

  1. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  2. GRB 250628A: REM optical/NIR upper limits
  3. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  4. GRB 250628A: VLT/X-shooter upper limits
  5. GRB 250628A: Swift/UVOT Upper Limits
  6. GRB 250628A: Enhanced Swift-XRT position
  7. GRB 250628A: Swift detection of a burst
  8. GRB 250625A: Leavitt Observatory afterglow detection
  9. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  10. GRB 250625A: SVOM/C-GFT upper limit in early phase
  11. GRB 250625A: Swift/UVOT Upper Limits
  12. GRB 250625A: ABObservatory afterglow detection
  13. GRB 250625A: OHP/T193 optical detection
  14. GRB 250625A: COLIBRÍ optical observations
  15. GRB 250625A: JinShan optical observations
  16. GRB 250625A: SAO RAS possible optical afterglow
  17. GRB 250625A: Enhanced Swift-XRT position
  18. GRB 250625A: Swift detection of a burst
  19. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  20. GRB 250620A: AstroSat CZTI detection
  21. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  22. GRB 241018A: Maidanak optical observations
  23. IPN triangulation of GRB 250620С (long/bright)
  24. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  25. GRB 250620C: SVOM/GRM observation
  26. GRB 250620A: SVOM/GRM observation of a short burst
  27. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  28. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  29. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  30. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  31. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  32. GRB 250617B: Nickel telescope optical observations
  33. GRB 250615A: Kilonova-Catcher optical upper limits
  34. GRB 250617B: Assy AZT-20 Optical Observations
  35. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  36. GRB 250617B: Swift/UVOT Detection
  37. GRB 250617B: Kilonova-Catcher optical afterglow detection
  38. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  39. GRB 250617B: COLIBRÍ optical observations
  40. GRB 250617B: NOT NIR observations of the afterglow
  41. GRB 250617B: NUTTelA-TAO early time optical observations
  42. GRB 250617B: Enhanced Swift-XRT position
  43. The EP-WXT trigger 01709178990 is likely a flaring star
  44. GRB 250617B: SAO RAS optical observations
  45. GRB 250617B: Swift detection of a burst with an optical counterpart
  46. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  47. EP-WXT trigger 01709178975: GOTO optical upper limit
  48. GRB 250615A / EP250615a: AstroSat CZTI detection
  49. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  50. GRB 250615A: COLIBRÍ optical upper limit
  51. GRB 250615A: DDOTI Optical Upper Limit
  52. GRB 250615A: Swift/UVOT Upper Limits
  53. sb25061207/SVOM: T120 OHP optical upper limit
  54. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  55. GRB 250615A: Enhanced Swift-XRT position
  56. GRB 250615A: Swift detection of a burst
  57. sb25061207: Mephisto optical upper limits
  58. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  59. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  60. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  62. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  63. sb25061207: EP-FXT follow-up observation and afterglow candidate
  64. EP250612a: SVOM/VT optical candidate
  65. sb25061218: SVOM detection of a X-ray transient
  66. EP250612a/GRB 250612B: JinShan optical upper limit
  67. sb25061207: SVOM/VT optical counterpart
  68. GRB 250610B: Swift-XRT refined Analysis
  69. EP250612a: Einstein Probe detection of an X-ray transient
  70. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  71. sb25061207: SVOM detection of a X-ray transient
  72. GRB 250610B: Swift/UVOT Detection
  73. EP250610A: Swift/UVOT Upper limits
  74. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  75. EP250610a: TNG NIR upper limit
  76. GRB 250610B: REM optical/NIR observations
  77. EP250610a: Liverpool Telescope optical upper limits
  78. GRB 250610B: additional Liverpool Telescope optical observations
  79. GRB 250610B: SVOM/VT optical counterpart
  80. GRB 250610B: OHP/T120 optical counterpart candidate
  81. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  82. GRB 250610B: SVOM detection of a long burst
  83. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  84. EP250610a: SVOM/VT optical upper limit
  85. EP250610a: REM optical/NIR observations
  86. EP250610a: COLIBRÍ optical upper limit
  87. EP250610a: Einstein Probe detection of an X-ray transient
  88. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  89. GRB 250605A: Swift/UVOT Upper Limits
  90. GRB 250527C: CrAO Optical Upper Limit
  91. GRB 250607A: SVOM/GRM observation of a long burst
  92. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  93. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  94. The EP-WXT trigger 01709178069 is likely a flaring star
  95. GRB 250605A: Enhanced Swift-XRT position
  96. Fermi trigger No 770867684: Global MASTER-Net observations report
  97. GRB 250605A: Swift detection of a burst
  98. IPN triangulation of GRB 250404B
  99. IPN triangulation of GRB 250529A
  100. GRB 250601A: PRIME H band upper limit.

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