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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

18056 results found.

  1. GRB 250530A: SVOM detection of a burst
  2. GRB 250527C: Swift/UVOT Upper Limits
  3. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  4. GRB 250527B: Swift-XRT observations
  5. Fermi trigger No 770047117: Global MASTER-Net observations report
  6. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  7. GRB 250314A: CIDER NB1008 upper limit
  8. EP250526a: COLIBRÍ optical upper limits
  9. EP250526a: Einstein Probe detection of a fast X-ray transient
  10. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  11. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  12. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  13. GRB 250521D: DDOTI Optical Upper Limit
  14. The EP-WXT trigger 01709176612 is likely a flaring star
  15. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. GRB 250521D: LAST tentative optical counterpart candidate
  17. GRB 250520A: 10 GHz VLA radio source
  18. GRB 250521A: DDOTI Optical Upper Limit
  19. GRB 250520A: VLT/FORS2 Optical Observation
  20. GRB 250502A: Tautenburg observations
  21. GRB 250520A: Swift/UVOT Upper Limits
  22. Konus-Wind detection of GRB 250516B
  23. IPN triangulation of GRB 250516B
  24. GRB 250520A: J-band observations with WINTER
  25. GRB 250520A: Gemini-South optical observations
  26. GRB 250520A: REM optical/NIR early observations
  27. GRB 250520A:SVOM/VT optical candidate
  28. GRB 250520A: COLIBRÍ optical upper limit
  29. GRB 250520A: DDOTI Optical Upper Limit
  30. GRB 250520A: Enhanced Swift-XRT position
  31. GRB 250520A: Swift detection of a burst
  32. GRB 250516A: COLIBRÍ optical upper limit
  33. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  34. GRB 250515A: Swift-XRT observations
  35. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  36. GRB 250515A: 1.6m Mephisto optical detection
  37. GRB 250516A: Swift/UVOT Detection
  38. GRB 250516A: Enhanced Swift-XRT position
  39. GRB 250516A: Swift detection of a burst
  40. GRB 250424A: COLIBRÍ detection of the associated supernova
  41. GRB 250502A: TESS observations
  42. EP250512a/GRB 250512B: REM optical/NIR observations
  43. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  44. EP250511a: Gemini optical counterpart observation
  45. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  46. EP250511a: Mephisto optical upper limits
  47. GRB 250512B: SVOM detection of a burst
  48. EP250512a: Einstein Probe detection of an X-ray transient
  49. EP250511a: REM optical/NIR observations
  50. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  51. EP250511a: COLIBRÍ optical counterpart candidate
  52. EP250511a: Einstein Probe detection of an X-ray transient
  53. EP250508a: Gemini NIR upper limits
  54. GRB 250510A: Swift-XRT observations
  55. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  56. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  57. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. GRB 250507A: J-band observations with WINTER
  59. GRB 250509A: Enhanced Swift-XRT position
  60. GRB 250509A: Swift detection of a burst
  61. GRB 250506A: NOT optical upper limits
  62. EP250508a: Liverpool Telescope optical upper limits
  63. EP250508a: KAIT optical upper limit
  64. GRB 250507A: KAIT optical upper limit
  65. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  66. GRB 250505B: SVOM/GRM observation of a short burst
  67. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  68. EP250508a: REM optical/NIR observations
  69. GRB 250506A: Swift-XRT afterglow detection
  70. EP250508a: COLIBRÍ Optical Limit
  71. EP250508a: Einstein Probe detection of an X-ray transient
  72. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 250506A: Swift/UVOT Upper Limits
  74. GRB 250427B : SVOM detection of a burst through offline search
  75. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. GRB 250507A: REM optical/NIR observations
  77. GRB 250507A: SVOM/VT optical upper limit
  78. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  80. GRB 250507A: SVOM detection of a long burst
  81. GRB 250506A: Mephisto optical upper limits
  82. GRB 250502A: Bassano Bresciano Observatory upper limit
  83. GRB 250506A: Xinglong 2.16m optical upper limit
  84. GRB 250506A: REM optical/NIR upper limits
  85. GRB 250506A: TRT optical observations
  86. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  87. GRB 250504A: VLT/X-shooter upper limits
  88. GRB 250504A: REM optical/NIR observations
  89. GRB 250502A: REM optical/NIR observations
  90. GRB 250504A: MeerLICHT optical afterglow detection
  91. GRB 250504A: Enhanced Swift-XRT position
  92. GRB 250504A: Swift detection of a burst
  93. GRB 250504A: Fermi GBM Final Real-time Localization
  94. GRB 250502A: Swift/UVOT Follow up
  95. GRB 250502A: KAIT optical observations
  96. GRB 250502A: Montarrenti Observatory optical detection
  97. GRB 250502A: Swift-XRT afterglow detection
  98. GRB 250502A: NOT optical observations
  99. GRB 250502B: AstroSat CZTI detection
  100. GRB 250502A: AKO Optical Afterglow Detection

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