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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"

36403 results found.

  1. GRB 250509A: Prompt enhanced Swift-XRT position
  2. Fermi GRB 250509A: Global MASTER-Net observations report
  3. Swift GRB 250509A: Global MASTER-Net observations report
  4. GRB 250509A: Swift detection of a burst
  5. GRB 250509A: Fermi GBM Final Real-time Localization
  6. GRB 250506A: NOT optical upper limits
  7. EP250508a: KAIT optical upper limit
  8. GRB 250507A: KAIT optical upper limit
  9. GRB 250505B: SVOM/GRM observation of a short burst
  10. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  11. GRB 250506A: GECAM detection
  12. EP250508a: REM optical/NIR observations
  13. GRB 250506A: Swift-XRT afterglow detection
  14. GRB 250506A: SVOM/VT optical upper limit
  15. GRB 250507A: Swift-XRT refined Analysis
  16. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 250506A: Swift/UVOT Upper Limits
  18. GRB 250427B : SVOM detection of a burst through offline search
  19. GRB 250507A: follow-up observation with EP-FXT
  20. GRB 250430A / EP250430a: AstroSat CZTI detection
  21. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. GRB 250507A: refined SVOM/MXT data analysis
  23. GRB 250507A: REM optical/NIR observations
  24. GRB 250507A: SVOM/VT optical upper limit
  25. GRB 250506A: Swift-XRT observations
  26. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  27. GRB 250507A: SVOM detection of a long burst
  28. GRB 250506A: Mephisto optical upper limits
  29. GRB 250504A: EIRSAT-1 GMOD Detection
  30. GRB 250506A: Swift ToO observations
  31. GRB 250502A: Bassano Bresciano Observatory upper limit
  32. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  33. GRB 250506A: Xinglong 2.16m optical upper limit
  34. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  35. GRB 250506A: REM optical/NIR upper limits
  36. GRB 250506A: Fermi GBM Observation
  37. GRB 250506A: Swift XRT observations and possible counterpart detection
  38. GRB 250506A: TRT optical observations
  39. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  40. GRB 250506A: SVOM detection of a burst
  41. GRB 250504A: Swift-BAT refined analysis
  42. GRB 250430A: Swift-BAT refined analysis
  43. GRB 250506A: Fermi GBM Final Real-time Localization
  44. GRB 250504A: Swift-XRT refined Analysis
  45. GRB 250504A: VLT/X-shooter upper limits
  46. Fermi GRB 250505A: Global MASTER-Net observations report
  47. GRB 250504A: SVOM/VT upper limit
  48. GRB 250504A: REM optical/NIR observations
  49. GRB 250502A: REM optical/NIR observations
  50. GRB 250505A: Fermi GBM Final Real-time Localization
  51. GRB 250504A: MeerLICHT optical afterglow detection
  52. GRB 250504A: Fermi GBM Observation
  53. GRB 250504A: Enhanced Swift-XRT position
  54. Fermi GRB 250504A: Global MASTER-Net observations report
  55. GRB 250504A: Swift detection of a burst
  56. GRB 250504A: Fermi GBM Final Real-time Localization
  57. GRB 250502A: Swift/UVOT Follow up
  58. GRB 250502A: Mondy and Tien-Shan Optical Observations
  59. GRB 250502A: KAIT optical observations
  60. GRB 250502A: Montarrenti Observatory optical detection
  61. GRB 250502A: Swift-XRT afterglow detection
  62. GRB 250502A: NOT optical observations
  63. GRB 250502a: Liverpool Telescope optical follow-up
  64. GRB 250502B: AstroSat CZTI detection
  65. GRB 250502A: AKO Optical Afterglow Detection
  66. GRB 250502A: LCO optical counterpart detection
  67. GRB 250502A: Swift ToO observations
  68. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  69. GRB 250502C: Fermi GBM Final Localization
  70. GRB 250407A: VZLUSAT-2 detection
  71. GRB 250502B: DDOTI Optical Observations
  72. GRB 250430A: Swift-XRT refined Analysis
  73. GRB 250502A: Early optical counterpart detection by LCO.
  74. GRB 250430A: Swift/UVOT Detection
  75. GRB 250502A: SVOM/VT optical bump
  76. GRB 250502A: TRT optical afterglow confirmation
  77. GRB 250430A: Enhanced Swift-XRT position
  78. Fermi GRB 250502B: Global MASTER-Net observations report
  79. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  80. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  81. GRB 250502B: Fermi GBM Final Real-time Localization
  82. GRB 250502A: SVOM detection of a burst
  83. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  84. GRB 250430A: SVOM/VT optical observations
  85. GRB 250430A: KAIT optical observations
  86. GRB 250430A / EP250430a: J-band upper limits with WINTER
  87. GRB 250430A: NUTTelA-TAO Early Measurements
  88. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  89. GRB 250430A: DDOTI Optical Observations
  90. GRB 250430A: Leavitt Observatory optical upper limit
  91. GRB 250430A: Bassano Bresciano Observatory upper limit
  92. GRB 250430A : MITSuME Akeno optical upper limits
  93. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  94. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  95. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  96. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  97. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 250430A: AKO Optical Afterglow Detection
  99. GRB 250430A: Kanata optical upper limit
  100. EP 250427A: Optical counterpart detection by LCO.

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