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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').
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"

20966 results found.

  1. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  2. Fermi GRB 250623A: Global MASTER-Net observations report
  3. Fermi trigger No 772190032: Global MASTER-Net observations report
  4. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  5. Fermi GRB 250621A: Global MASTER-Net observations report
  6. GRB 250506A - SVOM/ECLAIRs Refined analysis
  7. Fermi trigger No 772128434: Global MASTER-Net observations report
  8. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  9. GRB 250617B: Nickel telescope optical observations
  10. Fermi trigger No 772058337: Global MASTER-Net observations report
  11. GRB 250615A: Kilonova-Catcher optical upper limits
  12. GRB 250617B: Assy AZT-20 Optical Observations
  13. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  14. Fermi GRB 250617A: Global MASTER-Net observations report
  15. GRB 250615A/EP250615a: FTW optical and NIR observations
  16. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  17. GRB 250617B: Swift/UVOT Detection
  18. GRB 250617B: Kilonova-Catcher optical afterglow detection
  19. GRB 250617B: COLIBRÍ optical observations
  20. GRB 250617B: NOT NIR observations of the afterglow
  21. GRB 250617B: NUTTelA-TAO early time optical observations
  22. Fermi trigger No 771886893: Global MASTER-Net observations report
  23. Swift GRB 250617B: Global MASTER-Net observations report
  24. GRB 250617B: GOTO optical upper limit
  25. GRB 250617B: SAO RAS optical observations
  26. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  27. EP#01709178975: Swift-XRT counterpart detection
  28. EP-WXT trigger 01709178975: GOTO optical upper limit
  29. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  30. GRB 250615A: DDOTI Optical Upper Limit
  31. GRB 250615A: Swift/UVOT Upper Limits
  32. Fermi trigger No 771752663: Global MASTER-Net observations report
  33. Swift GRB 250615A: Global MASTER-Net observations report
  34. Fermi trigger No 771718064: Global MASTER-Net observations report
  35. sb25061207: Mephisto optical upper limits
  36. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  37. Fermi trigger No 771494087: Global MASTER-Net observations report
  38. sb25061218: Swift-XRT observations
  39. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  40. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  41. Fermi trigger No 771424081: Global MASTER-Net observations report
  42. EP250612a: Global MASTER-Net observations report
  43. sb25061207: Swift-XRT observations
  44. EP250612a/GRB 250612B: JinShan optical upper limit
  45. EP250610a: Upper limit from Fermi-GBM Observations
  46. GRB 250610B: Liverpool Telescope continued monitoring
  47. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  48. EP250610a: continuous follow-up observations with EP-FXT
  49. GRB 250610B - SVOM/ECLAIRs refined analysis
  50. Swift GRB250612.04: Global MASTER-Net observations report
  51. GRB 250610B: Swift/UVOT Detection
  52. EP250610A: Swift/UVOT Upper limits
  53. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  54. GRB 250610B: REM optical/NIR observations
  55. GRB 250610B: SVOM/VT optical shallow decay
  56. GRB 250610B: additional Liverpool Telescope optical observations
  57. GRB 250610B: Swift-XRT counterpart detection
  58. GRB 250610B: LT detection of the optical counterpart
  59. GRB 250610B: GOTO optical upper limit
  60. EP250610a: Global MASTER-Net observations report
  61. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  62. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  63. EP250610a: REM optical/NIR observations
  64. EP250610a: Swift-XRT counterpart detection
  65. EP250610a: COLIBRÍ optical upper limit
  66. Fermi trigger No 771072240: Global MASTER-Net observations report
  67. GRB 250605A: Swift/UVOT Upper Limits
  68. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  69. GRB 250527C: CrAO Optical Upper Limit
  70. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  71. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  72. GRB 250605A: SVOM/VT optical upper limit
  73. EP/WXT 01709177873: GOTO observations confirm stellar variability
  74. Fermi GRB 250606A: Global MASTER-Net observations report
  75. Fermi trigger No 770867684: Global MASTER-Net observations report
  76. GRB 250605A: LT optical observations
  77. Swift GRB250605.79: Global MASTER-Net observations report
  78. GRB 250601A: PRIME H band upper limit.
  79. GRB 250530A: SVOM/GRM analysis
  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. Fermi trigger No 770638414: Global MASTER-Net observations report
  85. Swift GRB250603.05: Global MASTER-Net observations report
  86. GRB 250602A: DDOTI Optical Upper Limit
  87. GRB 250521C: NOT spectroscopic observations exclude the afterglow candidate AT2025mgj
  88. GRB 250601A: Swift/XRT candidate afterglow
  89. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  90. GRB 250601A: Swift-XRT observations
  91. Fermi GRB 250601A: Global MASTER-Net observations report
  92. Fermi trigger No 770470765: Global MASTER-Net observations report
  93. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  94. GRB 250601A: Swift ToO observations
  95. GRB 250521C/AT2025mgj: FTW optical and NIR observations
  96. EP#01709177494: SVOM/VT optical observations
  97. Fermi GRB 250531A: Global MASTER-Net observations report
  98. EP#01709177494: Swift-XRT counterpart detection of known source
  99. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  100. Swift GRB 250530C: Global MASTER-Net observations report

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