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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"

36310 results found.

  1. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  2. GRB 250509A: Swift-XRT refined Analysis
  3. GRB 250510A: SVOM possible detection of a burst
  4. GRB 250507A: J-band observations with WINTER (duplicate submission)
  5. GRB 250507A: J-band observations with WINTER
  6. GRB 250509A: Enhanced Swift-XRT position
  7. GRB 250509A: Prompt enhanced Swift-XRT position
  8. Fermi GRB 250509A: Global MASTER-Net observations report
  9. Swift GRB 250509A: Global MASTER-Net observations report
  10. GRB 250509A: Swift detection of a burst
  11. GRB 250509A: Fermi GBM Final Real-time Localization
  12. GRB 250506A: NOT optical upper limits
  13. EP250508a: KAIT optical upper limit
  14. GRB 250507A: KAIT optical upper limit
  15. GRB 250505B: SVOM/GRM observation of a short burst
  16. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  17. GRB 250506A: GECAM detection
  18. EP250508a: REM optical/NIR observations
  19. GRB 250506A: Swift-XRT afterglow detection
  20. GRB 250506A: SVOM/VT optical upper limit
  21. GRB 250507A: Swift-XRT refined Analysis
  22. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 250506A: Swift/UVOT Upper Limits
  24. GRB 250427B : SVOM detection of a burst through offline search
  25. GRB 250507A: follow-up observation with EP-FXT
  26. GRB 250430A / EP250430a: AstroSat CZTI detection
  27. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  28. GRB 250507A: refined SVOM/MXT data analysis
  29. GRB 250507A: REM optical/NIR observations
  30. GRB 250507A: SVOM/VT optical upper limit
  31. GRB 250506A: Swift-XRT observations
  32. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. GRB 250507A: SVOM detection of a long burst
  34. GRB 250506A: Mephisto optical upper limits
  35. GRB 250504A: EIRSAT-1 GMOD Detection
  36. GRB 250506A: Swift ToO observations
  37. GRB 250502A: Bassano Bresciano Observatory upper limit
  38. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  39. GRB 250506A: Xinglong 2.16m optical upper limit
  40. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  41. GRB 250506A: REM optical/NIR upper limits
  42. GRB 250506A: Fermi GBM Observation
  43. GRB 250506A: Swift XRT observations and possible counterpart detection
  44. GRB 250506A: TRT optical observations
  45. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  46. GRB 250506A: SVOM detection of a burst
  47. GRB 250504A: Swift-BAT refined analysis
  48. GRB 250430A: Swift-BAT refined analysis
  49. GRB 250506A: Fermi GBM Final Real-time Localization
  50. GRB 250504A: Swift-XRT refined Analysis
  51. GRB 250504A: VLT/X-shooter upper limits
  52. Fermi GRB 250505A: Global MASTER-Net observations report
  53. GRB 250504A: SVOM/VT upper limit
  54. GRB 250504A: REM optical/NIR observations
  55. GRB 250502A: REM optical/NIR observations
  56. GRB 250505A: Fermi GBM Final Real-time Localization
  57. GRB 250504A: MeerLICHT optical afterglow detection
  58. GRB 250504A: Fermi GBM Observation
  59. GRB 250504A: Enhanced Swift-XRT position
  60. Fermi GRB 250504A: Global MASTER-Net observations report
  61. GRB 250504A: Swift detection of a burst
  62. GRB 250504A: Fermi GBM Final Real-time Localization
  63. GRB 250502A: Swift/UVOT Follow up
  64. GRB 250502A: Mondy and Tien-Shan Optical Observations
  65. GRB 250502A: KAIT optical observations
  66. GRB 250502A: Montarrenti Observatory optical detection
  67. GRB 250502A: Swift-XRT afterglow detection
  68. GRB 250502A: NOT optical observations
  69. GRB 250502a: Liverpool Telescope optical follow-up
  70. GRB 250502B: AstroSat CZTI detection
  71. GRB 250502A: AKO Optical Afterglow Detection
  72. GRB 250502A: LCO optical counterpart detection
  73. GRB 250502A: Swift ToO observations
  74. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  75. GRB 250502C: Fermi GBM Final Localization
  76. GRB 250407A: VZLUSAT-2 detection
  77. GRB 250502B: DDOTI Optical Observations
  78. GRB 250430A: Swift-XRT refined Analysis
  79. GRB 250502A: Early optical counterpart detection by LCO.
  80. GRB 250430A: Swift/UVOT Detection
  81. GRB 250502A: SVOM/VT optical bump
  82. GRB 250502A: TRT optical afterglow confirmation
  83. GRB 250430A: Enhanced Swift-XRT position
  84. Fermi GRB 250502B: Global MASTER-Net observations report
  85. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  86. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  87. GRB 250502B: Fermi GBM Final Real-time Localization
  88. GRB 250502A: SVOM detection of a burst
  89. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  90. GRB 250430A: SVOM/VT optical observations
  91. GRB 250430A: KAIT optical observations
  92. GRB 250430A / EP250430a: J-band upper limits with WINTER
  93. GRB 250430A: NUTTelA-TAO Early Measurements
  94. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  95. GRB 250430A: DDOTI Optical Observations
  96. GRB 250430A: Leavitt Observatory optical upper limit
  97. GRB 250430A: Bassano Bresciano Observatory upper limit
  98. GRB 250430A : MITSuME Akeno optical upper limits
  99. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  100. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission

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