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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"

21770 results found.

  1. GRB 250625A: COLIBRÍ optical observations
  2. GRB 250625A: Fermi-LAT detection
  3. GRB 250625A: JinShan optical observations
  4. GRB 250625A: SAO RAS possible optical afterglow
  5. GRB 250625A: Enhanced Swift-XRT position
  6. GRB 250625A: Swift detection of a burst
  7. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  8. GRB 241018A: Maidanak optical observations
  9. GRB 250620C: AstroSat CZTI detection
  10. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  11. GRB 250521A: VZLUSAT-2 detection
  12. Konus-Wind detection of GRB 250620C
  13. IPN triangulation of GRB 250620C (long/bright)
  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 250506A - SVOM/ECLAIRs Refined analysis
  19. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  20. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  21. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  22. GRB 250617B: Nickel telescope optical observations
  23. GRB 250615A: Kilonova-Catcher optical upper limits
  24. GRB 250617B: Assy AZT-20 Optical Observations
  25. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  26. GRB 250617B: Swift/UVOT Detection
  27. GRB 250617B: Kilonova-Catcher optical afterglow detection
  28. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  29. GRB 250617B: COLIBRÍ optical observations
  30. GRB 250617B: NOT NIR observations of the afterglow
  31. GRB 250617B: NUTTelA-TAO early time optical observations
  32. GRB 250617B: Enhanced Swift-XRT position
  33. GRB 250615A: Swift-BAT refined analysis
  34. GRB 250617B: SAO RAS optical observations
  35. GRB 250617B: Swift detection of a burst with an optical counterpart
  36. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  37. EP-WXT trigger 01709178975: GOTO optical upper limit
  38. Konus-Wind detection of GRB 250615A / EP250615a
  39. GRB 250615A / EP250615a: AstroSat CZTI detection
  40. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  41. GRB 250615A: COLIBRÍ optical upper limit
  42. GRB 250615A: DDOTI Optical Upper Limit
  43. GRB 250615A: Swift/UVOT Upper Limits
  44. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  45. sb25061207/SVOM: T120 OHP optical upper limit
  46. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  47. GRB 250615A: Enhanced Swift-XRT position
  48. GRB 250615A: Swift detection of a burst
  49. Swift GRB 250615A: Global MASTER-Net observations report
  50. sb25061207: Mephisto optical upper limits
  51. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  52. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  53. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  54. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  55. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  56. EP250612a: SVOM/VT optical candidate
  57. EP250612a/GRB 250612B: JinShan optical upper limit
  58. sb25061207: SVOM/VT optical counterpart
  59. GRB 250610B: Swift-XRT refined Analysis
  60. EP250612a: Einstein Probe detection of an X-ray transient
  61. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  62. sb25061207: SVOM detection of a X-ray transient
  63. GRB 250610B - SVOM/ECLAIRs refined analysis
  64. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  65. Fermi GBM Sub-Threshold Detection of GRB 250610B
  66. GRB 250610B: Swift/UVOT Detection
  67. EP250610A: Swift/UVOT Upper limits
  68. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  69. EP250610a: TNG NIR upper limit
  70. GRB 250610B: REM optical/NIR observations
  71. EP250610a: Liverpool Telescope optical upper limits
  72. GRB 250610B: additional Liverpool Telescope optical observations
  73. GRB 250610B: SVOM/VT optical counterpart
  74. GRB 250610B: OHP/T120 optical counterpart candidate
  75. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  76. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  77. EP250610a: SVOM/VT optical upper limit
  78. EP250610a: REM optical/NIR observations
  79. EP250610a: COLIBRÍ optical upper limit
  80. EP250610a: Einstein Probe detection of an X-ray transient
  81. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  82. GRB 250605A: Swift/UVOT Upper Limits
  83. The EP-WXT trigger 01709178283 is likely a flaring star
  84. GRB 250527C: CrAO Optical Upper Limit
  85. GRB 250607A: SVOM/GRM observation of a long burst
  86. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  87. GRB 250605A: Enhanced Swift-XRT position
  88. GRB 250605A: Swift detection of a burst
  89. IPN triangulation of GRB 250404B
  90. IPN triangulation of GRB 250529A
  91. GRB 250601A: PRIME H band upper limit.
  92. GRB 250601A: PRIME J band upper limit.
  93. GRB 250601A: VLT/FORS2 Optical Observation
  94. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  95. GRB 250603A: Swift/UVOT Upper Limits
  96. GRB 250603A: Enhanced Swift-XRT position
  97. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  98. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  99. GRB 250602A: DDOTI Optical Upper Limit
  100. EP#01709177494: SVOM/VT optical observations

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