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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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.

Advanced Search Examples (click to copy):

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

36000 results found.

  1. GRB 250509A: Swift-BAT refined analysis
  2. Fermi GRB 250512A: Global MASTER-Net observations report
  3. Konus-Wind detection of GRB 250506A
  4. EP250512a/GRB 250512B: REM optical/NIR observations
  5. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  6. GRB 250507B: AstroSat CZTI detection
  7. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  8. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  9. GRB 250512B/EP250512a: SVOM/VT optical fading
  10. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  11. GRB 250507B: GRBAlpha detection
  12. GRB 250506A: GRBAlpha detection
  13. GRB 250512B: SVOM detection of a burst
  14. GRB 250507B: SVOM/GRM observation of a burst
  15. GRB 250512A: Fermi GBM Final Real-time Localization
  16. EP250511a: REM optical/NIR observations
  17. GRB 250510B: Fermi GBM Observation
  18. Fermi GRB 250510C: Global MASTER-Net observations report
  19. Fermi GRB 250510B: Global MASTER-Net observations report
  20. GRB 250510C: Fermi GBM Final Real-time Localization
  21. GRB 250510A: Swift-XRT observations
  22. GRB 250509A: Fermi GBM Observation
  23. GRB 250510A: follow-up observation with EP-FXT
  24. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  25. GRB 250510B: Fermi GBM Final Localization
  26. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  27. GRB 250509A: Swift-XRT refined Analysis
  28. GRB 250510A: SVOM possible detection of a burst
  29. GRB 250507A: J-band observations with WINTER (duplicate submission)
  30. GRB 250507A: J-band observations with WINTER
  31. GRB 250509A: Enhanced Swift-XRT position
  32. GRB 250509A: Prompt enhanced Swift-XRT position
  33. Fermi GRB 250509A: Global MASTER-Net observations report
  34. Swift GRB 250509A: Global MASTER-Net observations report
  35. GRB 250509A: Swift detection of a burst
  36. GRB 250509A: Fermi GBM Final Real-time Localization
  37. GRB 250506A: NOT optical upper limits
  38. EP250508a: KAIT optical upper limit
  39. GRB 250507A: KAIT optical upper limit
  40. GRB 250505B: SVOM/GRM observation of a short burst
  41. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  42. GRB 250506A: GECAM detection
  43. EP250508a: REM optical/NIR observations
  44. GRB 250506A: Swift-XRT afterglow detection
  45. GRB 250506A: SVOM/VT optical upper limit
  46. GRB 250507A: Swift-XRT refined Analysis
  47. GRB 250506A: Swift/UVOT Upper Limits
  48. GRB 250427B : SVOM detection of a burst through offline search
  49. GRB 250507A: follow-up observation with EP-FXT
  50. GRB 250430A / EP250430a: AstroSat CZTI detection
  51. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. GRB 250507A: refined SVOM/MXT data analysis
  53. GRB 250507A: REM optical/NIR observations
  54. GRB 250507A: SVOM/VT optical upper limit
  55. GRB 250506A: Swift-XRT observations
  56. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  57. GRB 250507A: SVOM detection of a long burst
  58. GRB 250506A: Mephisto optical upper limits
  59. GRB 250504A: EIRSAT-1 GMOD Detection
  60. GRB 250506A: Swift ToO observations
  61. GRB 250502A: Bassano Bresciano Observatory upper limit
  62. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  63. GRB 250506A: Xinglong 2.16m optical upper limit
  64. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  65. GRB 250506A: REM optical/NIR upper limits
  66. GRB 250506A: Fermi GBM Observation
  67. GRB 250506A: Swift XRT observations and possible counterpart detection
  68. GRB 250506A: TRT optical observations
  69. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  70. GRB 250506A: SVOM detection of a burst
  71. GRB 250504A: Swift-BAT refined analysis
  72. GRB 250430A: Swift-BAT refined analysis
  73. GRB 250506A: Fermi GBM Final Real-time Localization
  74. GRB 250504A: Swift-XRT refined Analysis
  75. GRB 250504A: VLT/X-shooter upper limits
  76. Fermi GRB 250505A: Global MASTER-Net observations report
  77. GRB 250504A: SVOM/VT upper limit
  78. GRB 250504A: REM optical/NIR observations
  79. GRB 250502A: REM optical/NIR observations
  80. GRB 250505A: Fermi GBM Final Real-time Localization
  81. GRB 250504A: MeerLICHT optical afterglow detection
  82. GRB 250504A: Fermi GBM Observation
  83. GRB 250504A: Enhanced Swift-XRT position
  84. Fermi GRB 250504A: Global MASTER-Net observations report
  85. GRB 250504A: Swift detection of a burst
  86. GRB 250504A: Fermi GBM Final Real-time Localization
  87. GRB 250502A: Swift/UVOT Follow up
  88. GRB 250502A: Mondy and Tien-Shan Optical Observations
  89. GRB 250502A: KAIT optical observations
  90. GRB 250502A: Montarrenti Observatory optical detection
  91. GRB 250502A: Swift-XRT afterglow detection
  92. GRB 250502A: NOT optical observations
  93. GRB 250502a: Liverpool Telescope optical follow-up
  94. GRB 250502B: AstroSat CZTI detection
  95. GRB 250502A: AKO Optical Afterglow Detection
  96. GRB 250502A: LCO optical counterpart detection
  97. GRB 250502A: Swift ToO observations
  98. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  99. GRB 250502C: Fermi GBM Final Localization
  100. GRB 250407A: VZLUSAT-2 detection

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