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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"

18109 results found.

  1. EP250612a: Einstein Probe detection of an X-ray transient
  2. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  3. sb25061207: SVOM detection of a X-ray transient
  4. GRB 250610B - SVOM/ECLAIRs refined analysis
  5. Swift GRB250612.04: Global MASTER-Net observations report
  6. GRB 250610B: Swift/UVOT Detection
  7. EP250610A: Swift/UVOT Upper limits
  8. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  9. EP250610a: TNG NIR upper limit
  10. GRB 250610B: REM optical/NIR observations
  11. EP250610a: Liverpool Telescope optical upper limits
  12. GRB 250610B: additional Liverpool Telescope optical observations
  13. GRB 250610B: SVOM/VT optical counterpart
  14. GRB 250610B: OHP/T120 optical counterpart candidate
  15. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  16. GRB 250610B: SVOM detection of a long burst
  17. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  18. EP250610a: SVOM/VT optical upper limit
  19. EP250610a: REM optical/NIR observations
  20. GRB 250609A: Fermi GBM Observation
  21. GRBAlpha reentry on June 9, 2025
  22. EP250610a: COLIBRÍ optical upper limit
  23. EP250610a: Einstein Probe detection of an X-ray transient
  24. Fermi trigger No 771072240: Global MASTER-Net observations report
  25. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  26. GRB 250605A: Swift/UVOT Upper Limits
  27. GRB 250527C: CrAO Optical Upper Limit
  28. GRB 250607A: SVOM/GRM observation of a long burst
  29. The EP-WXT trigger 01709178244 is likely a flaring star
  30. The EP-WXT trigger 01709178069 is likely a flaring star
  31. GRB 250605A: Enhanced Swift-XRT position
  32. GRB 250605A: Swift detection of a burst
  33. IPN triangulation of GRB 250404B
  34. IPN triangulation of GRB 250529A
  35. GRB 250601A: PRIME H band upper limit.
  36. GRB 250601A: PRIME J band upper limit.
  37. GRB 250601A: VLT/FORS2 Optical Observation
  38. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  39. GRB 250603A: Swift/UVOT Upper Limits
  40. GRB 250603A: Swift-XRT refined Analysis
  41. GRB 250603A: Enhanced Swift-XRT position
  42. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  43. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  44. GRB 250602A: DDOTI Optical Upper Limit
  45. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  46. EP#01709177494: SVOM/VT optical observations
  47. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  48. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  49. GRB 250530C: Enhanced Swift-XRT position
  50. GRB 250530C: Swift detection of a burst
  51. GRB 250530A: SVOM/VT optical upper limit
  52. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  53. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  54. GRB 250530A: SVOM detection of a burst
  55. GRB 250527C: Swift/UVOT Upper Limits
  56. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  57. GRB 250527B: Swift-XRT observations
  58. Fermi trigger No 770047117: Global MASTER-Net observations report
  59. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  60. GRB 250314A: CIDER NB1008 upper limit
  61. EP250526a: COLIBRÍ optical upper limits
  62. EP250526a: Einstein Probe detection of a fast X-ray transient
  63. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  64. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  65. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  66. GRB 250521D: DDOTI Optical Upper Limit
  67. The EP-WXT trigger 01709176612 is likely a flaring star
  68. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  69. GRB 250521D: LAST tentative optical counterpart candidate
  70. GRB 250520A: 10 GHz VLA radio source
  71. GRB 250521A: DDOTI Optical Upper Limit
  72. GRB 250520A: VLT/FORS2 Optical Observation
  73. GRB 250502A: Tautenburg observations
  74. GRB 250520A: Swift/UVOT Upper Limits
  75. Konus-Wind detection of GRB 250516B
  76. IPN triangulation of GRB 250516B
  77. GRB 250520A: J-band observations with WINTER
  78. GRB 250520A: Gemini-South optical observations
  79. GRB 250520A: REM optical/NIR early observations
  80. GRB 250520A:SVOM/VT optical candidate
  81. GRB 250520A: COLIBRÍ optical upper limit
  82. GRB 250520A: DDOTI Optical Upper Limit
  83. GRB 250520A: Enhanced Swift-XRT position
  84. GRB 250520A: Swift detection of a burst
  85. GRB 250516A: COLIBRÍ optical upper limit
  86. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  87. GRB 250515A: Swift-XRT observations
  88. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  89. GRB 250515A: 1.6m Mephisto optical detection
  90. GRB 250516A: Swift/UVOT Detection
  91. GRB 250516A: Enhanced Swift-XRT position
  92. GRB 250516A: Swift detection of a burst
  93. GRB 250424A: COLIBRÍ detection of the associated supernova
  94. GRB 250502A: TESS observations
  95. EP250512a/GRB 250512B: REM optical/NIR observations
  96. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  97. EP250511a: Gemini optical counterpart observation
  98. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  99. EP250511a: Mephisto optical upper limits
  100. GRB 250512B: SVOM detection of a burst

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