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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"

21948 results found.

  1. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  2. Swift GRB 250516A: Global MASTER-Net observations report
  3. GRB 250515A: 1.6m Mephisto optical detection
  4. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  5. GRB 250516A: Swift/UVOT Detection
  6. GRB 250515A: Swift ToO observations
  7. GRB 250515A: GOTO candidate optical counterpart
  8. MAXI GRB250515.65: Global MASTER-Net observations report
  9. GRB 250424A: COLIBRÍ detection of the associated supernova
  10. GRB 250502A: TESS observations
  11. Fermi trigger No 768922089: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  13. Fermi GRB 250512A: Global MASTER-Net observations report
  14. EP250512a/GRB 250512B: REM optical/NIR observations
  15. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  16. EP250511a: Gemini optical counterpart observation
  17. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  18. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  19. EP250512a: Global MASTER-Net observations report
  20. EP250511a: FTW optical and NIR observations
  21. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  22. EP250511a: Mephisto optical upper limits
  23. EP250511a: REM optical/NIR observations
  24. EP250511a: SVOM/VT optical candidate comfirmation
  25. EP250511a: Global MASTER-Net observations report
  26. EP250511a: COLIBRÍ optical counterpart candidate
  27. EP250508a: Gemini NIR upper limits
  28. Fermi GRB 250510C: Global MASTER-Net observations report
  29. Fermi GRB 250510B: Global MASTER-Net observations report
  30. GRB 250510A: Swift-XRT observations
  31. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  32. GRB 250510A: follow-up observation with EP-FXT
  33. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  34. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  35. GRB 250507A: J-band observations with WINTER (duplicate submission)
  36. GRB 250507A: J-band observations with WINTER
  37. Fermi GRB 250509A: Global MASTER-Net observations report
  38. Swift GRB 250509A: Global MASTER-Net observations report
  39. EP250508a: follow-up observation with EP-FXT
  40. GRB 250507A: KAIT optical upper limit
  41. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  42. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  43. EP250508a: REM optical/NIR observations
  44. GRB 250506A: Swift-XRT afterglow detection
  45. EP250508a: Global MASTER-Net observations report
  46. GRB 250506A: SVOM/VT optical upper limit
  47. EP250508a: COLIBRÍ Optical Limit
  48. GRB 250506A: Swift/UVOT Upper Limits
  49. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  50. GRB 250507A: refined SVOM/MXT data analysis
  51. GRB 250507A: REM optical/NIR observations
  52. GRB 250507A: SVOM/VT optical upper limit
  53. GRB 250506A: Swift-XRT observations
  54. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  55. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  56. GRB 250506A: Mephisto optical upper limits
  57. GRB 250506A: Swift ToO observations
  58. GRB 250502A: Bassano Bresciano Observatory upper limit
  59. IceCube Alert 250506.59: Global MASTER-Net observations report
  60. SVOM/sb25050601: EP-FXT observations
  61. GRB 250506A: REM optical/NIR upper limits
  62. GRB 250506A: Swift XRT observations and possible counterpart detection
  63. GRB 250506A: TRT optical observations
  64. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  65. Fermi GRB 250505A: Global MASTER-Net observations report
  66. GRB 250504A: SVOM/VT upper limit
  67. GRB 250504A: REM optical/NIR observations
  68. GRB 250502A: REM optical/NIR observations
  69. GRB 250504A: MeerLICHT optical afterglow detection
  70. Fermi GRB 250504A: Global MASTER-Net observations report
  71. Swift GRB250504.98: Global MASTER-Net observations report
  72. GRB 250502A: Swift/UVOT Follow up
  73. GRB 250502A: Mondy and Tien-Shan Optical Observations
  74. GRB 250502A: KAIT optical observations
  75. GRB 250502A: Montarrenti Observatory optical detection
  76. GRB 250502A: Swift-XRT afterglow detection
  77. Fermi trigger No 767975731: Global MASTER-Net observations report
  78. GRB 250502A: NOT optical observations
  79. GRB 250502a: Liverpool Telescope optical follow-up
  80. GRB 250502A: LCO optical counterpart detection
  81. GRB 250502A: Swift ToO observations
  82. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  83. GRB 250502B: DDOTI Optical Observations
  84. GRB 250502A: Early optical counterpart detection by LCO.
  85. GRB 250430A: Swift/UVOT Detection
  86. GRB 250502A: SVOM/VT optical bump
  87. GRB 250502A: TRT optical afterglow confirmation
  88. Fermi GRB 250502B: Global MASTER-Net observations report
  89. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  90. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  91. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  92. GRB 250430A: SVOM/VT optical observations
  93. GRB 250430A: KAIT optical observations
  94. EP250428b: Pan-STARRS follow-up, upper limit on the optical counterpart, and possible host galaxy.
  95. GRB 250430A / EP250430a: J-band upper limits with WINTER
  96. GRB 250430A: NUTTelA-TAO Early Measurements
  97. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  98. GRB 250430A: DDOTI Optical Observations
  99. GRB 250430A: Leavitt Observatory optical upper limit
  100. GRB 250430A: Bassano Bresciano Observatory upper limit

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