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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"

19666 results found.

  1. GRB 250628A: Swift-XRT refined Analysis
  2. Swift GRB 250628A: Global MASTER-Net observations report
  3. GRB 250628A: Enhanced Swift-XRT position
  4. GRB 250628A: Swift detection of a burst
  5. GRB 250625A: Swift-BAT refined analysis
  6. GRB 250625A: Leavitt Observatory afterglow detection
  7. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  8. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  9. GRB 250625A: SVOM/C-GFT upper limit in early phase
  10. GRB 250625A: GECAM-B detection
  11. GRB 250625A: Swift/UVOT Upper Limits
  12. GRB 250625A: ABObservatory afterglow detection
  13. GRB 250625A: COLIBRÍ optical observations
  14. GRB 250625A: Fermi-LAT detection
  15. GRB 250625A: Swift-XRT refined Analysis
  16. GRB 250625A: JinShan optical observations
  17. GRB250625A: Fermi GBM Observation
  18. Swift GRB 250625A: Global MASTER-Net observations report
  19. GRB 250625A: SVOM/VT optical confirmation
  20. GRB 250620B: Fermi GBM Observation
  21. GRB 250625A: Enhanced Swift-XRT position
  22. GRB 250625A: Swift detection of a burst
  23. GRB 250620A: AstroSat CZTI detection
  24. GRB 241018A: Maidanak optical observations
  25. GRB 250617B: Swift-BAT refined analysis
  26. IPN triangulation of GRB 250620C (long/bright)
  27. GRB 250620A: SVOM/GRM observation of a short burst
  28. GRB250620A: Fermi GBM Observation
  29. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  30. GRB 250619B: Fermi GBM Observation
  31. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  32. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  33. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  34. GRB 250615A: Kilonova-Catcher optical upper limits
  35. GRB 250617B: Assy AZT-20 Optical Observations
  36. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  37. GRB 250615A/EP250615a: FTW optical and NIR observations
  38. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  39. GRB 250617B: Swift/UVOT Detection
  40. GRB 250617B: Kilonova-Catcher optical afterglow detection
  41. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  42. GRB 250617B: NOT NIR observations of the afterglow
  43. GRB 250617B: Swift-XRT refined Analysis
  44. GRB 250617B: SVOM/VT optical observation
  45. Swift GRB 250617B: Global MASTER-Net observations report
  46. GRB 250617B: GOTO optical upper limit
  47. GRB 250617B: Enhanced Swift-XRT position
  48. GRB 250617B: Fermi GBM Observation
  49. GRB 250615A: Swift-BAT refined analysis
  50. GRB 250617B: Fermi GBM Final Localization
  51. GRB 250617B: Ondrejov D50 optical afterglow detection
  52. GRB 250617B: Swift detection of a burst with an optical counterpart
  53. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  54. EP#01709178975: Swift-XRT counterpart detection
  55. Konus-Wind detection of GRB 250615A / EP250615a
  56. GRB 250615A / EP250615a: AstroSat CZTI detection
  57. GRB 250615A: COLIBRÍ optical upper limit
  58. GRB 250615A: DDOTI Optical Upper Limit
  59. GRB 250615A: Swift/UVOT Upper Limits
  60. GRB 250615A: Swift-XRT refined Analysis
  61. GRB 250615A: Enhanced Swift-XRT position
  62. GRB 250615A: Prompt enhanced Swift-XRT position
  63. GRB 250615A: Swift detection of a burst
  64. Swift GRB 250615A: Global MASTER-Net observations report
  65. sb25061207: Mephisto optical upper limits
  66. sb25061218: Swift-XRT observations
  67. sb25061207: EP-FXT follow-up observation and afterglow candidate
  68. sb25061207: Swift-XRT observations
  69. GRB 250610B: Swift-XRT refined Analysis
  70. EP250610a: continuous follow-up observations with EP-FXT
  71. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  72. Swift GRB250612.04: Global MASTER-Net observations report
  73. GRB 250610B: Swift/UVOT Detection
  74. EP250610A: Swift/UVOT Upper limits
  75. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  76. GRB 250610B: Swift-XRT counterpart detection
  77. GRB 250610B: SVOM/VT optical counterpart
  78. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  79. GRB 250605A: Swift-BAT refined analysis
  80. EP250610a: SVOM/VT optical upper limit
  81. EP250610a: REM optical/NIR observations
  82. GRB 250609A: Fermi GBM Observation
  83. EP250610a: Swift-XRT counterpart detection
  84. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  85. GRB 250605A: Swift/UVOT Upper Limits
  86. GRB 250527C: CrAO Optical Upper Limit
  87. GRB 250605A: SVOM/VT optical upper limit
  88. GRB 250605A: Swift-XRT refined Analysis
  89. GRB 250605A: Enhanced Swift-XRT position
  90. GRB 250605A: LT optical observations
  91. GRB 250605A: Swift detection of a burst
  92. Swift GRB250605.79: Global MASTER-Net observations report
  93. Konus-Wind detection of GRB 250601A
  94. IPN triangulation of GRB 250404B
  95. IPN triangulation of GRB 250529A
  96. GRB 250601A: PRIME H band upper limit.
  97. GRB 250601A: PRIME J band upper limit.
  98. GRB 250601A: VLT/FORS2 Optical Observation
  99. GRB 250601A: Fermi GBM Observation
  100. GRB 250603A: Swift/UVOT Upper Limits

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