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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"

26059 results found.

  1. GRB 250702F: GOTO optical counterpart detection
  2. GRB 250702F: Ondrejov D50 optical afterglow detection
  3. GRB 250702F: Swift detection of a burst with an optical counterpart
  4. Swift GRB 250702F: Global MASTER-Net observations report
  5. GRB 250628B: Swift-XRT observations
  6. GRB 250628B: SVOM/VT optical upper limit
  7. GRB 250628A: REM optical/NIR upper limits
  8. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  9. GRB 250628A: VLT/X-shooter upper limits
  10. GRB 250628A: Swift/UVOT Upper Limits
  11. GRB 250628A: Swift-XRT refined Analysis
  12. Swift GRB 250628A: Global MASTER-Net observations report
  13. GRB 250628A: Enhanced Swift-XRT position
  14. GRB 250628A: Swift detection of a burst
  15. GRB 250625A: Swift-BAT refined analysis
  16. GRB 250625A: Leavitt Observatory afterglow detection
  17. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  18. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  19. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  20. GRB 250625A: SVOM/C-GFT upper limit in early phase
  21. GRB 250625A: GECAM-B detection
  22. GRB 250625A: Swift/UVOT Upper Limits
  23. GRB 250625A: ABObservatory afterglow detection
  24. GRB 250625A: COLIBRÍ optical observations
  25. GRB 250625A: Fermi-LAT detection
  26. GRB 250625A: Swift-XRT refined Analysis
  27. GRB 250625A: JinShan optical observations
  28. GRB250625A: Fermi GBM Observation
  29. Swift GRB 250625A: Global MASTER-Net observations report
  30. GRB 250625A: NOT z-band upper limit
  31. GRB 250625A: SVOM/VT optical confirmation
  32. GRB 250620B: Fermi GBM Observation
  33. GRB 250625A: SAO RAS possible optical afterglow
  34. GRB 250625A: Enhanced Swift-XRT position
  35. GRB 250625A: Swift detection of a burst
  36. GRB 250620A: AstroSat CZTI detection
  37. GRB 241018A: Maidanak optical observations
  38. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  39. GRB 250617B: Swift-BAT refined analysis
  40. IPN triangulation of GRB 250620C (long/bright)
  41. GRB 250620A: SVOM/GRM observation of a short burst
  42. GRB250620A: Fermi GBM Observation
  43. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  44. GRB 250619B: Fermi GBM Observation
  45. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  46. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  47. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  48. GRB 250617B: Nickel telescope optical observations
  49. GRB 250615A: Kilonova-Catcher optical upper limits
  50. GRB 250617B: Assy AZT-20 Optical Observations
  51. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  52. GRB 250615A/EP250615a: FTW optical and NIR observations
  53. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  54. GRB 250617B: Swift/UVOT Detection
  55. GRB 250617B: Kilonova-Catcher optical afterglow detection
  56. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  57. GRB 250617B: NOT NIR observations of the afterglow
  58. GRB 250617B: Swift-XRT refined Analysis
  59. GRB 250617B: SVOM/VT optical observation
  60. Swift GRB 250617B: Global MASTER-Net observations report
  61. GRB 250617B: GOTO optical upper limit
  62. GRB 250617B: Enhanced Swift-XRT position
  63. GRB 250617B: Fermi GBM Observation
  64. GRB 250615A: Swift-BAT refined analysis
  65. GRB 250617B: Fermi GBM Final Localization
  66. GRB 250617B: Ondrejov D50 optical afterglow detection
  67. GRB 250617B: Swift detection of a burst with an optical counterpart
  68. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  69. EP#01709178975: Swift-XRT counterpart detection
  70. Konus-Wind detection of GRB 250615A / EP250615a
  71. GRB 250615A / EP250615a: AstroSat CZTI detection
  72. GRB 250615A: COLIBRÍ optical upper limit
  73. GRB 250615A: DDOTI Optical Upper Limit
  74. GRB 250615A: Swift/UVOT Upper Limits
  75. GRB 250615A: Swift-XRT refined Analysis
  76. GRB 250615A: Enhanced Swift-XRT position
  77. GRB 250615A: Prompt enhanced Swift-XRT position
  78. GRB 250615A: Swift detection of a burst
  79. Swift GRB 250615A: Global MASTER-Net observations report
  80. sb25061207: Mephisto optical upper limits
  81. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  82. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  83. sb25061218: Swift-XRT observations
  84. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  85. sb25061207: EP-FXT follow-up observation and afterglow candidate
  86. sb25061207: Swift-XRT observations
  87. EP 250612a: AST3-3 Yaoan Optical Observation
  88. GRB 250610B: Swift-XRT refined Analysis
  89. EP250610a: continuous follow-up observations with EP-FXT
  90. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  91. Swift GRB250612.04: Global MASTER-Net observations report
  92. GRB 250610B: Swift/UVOT Detection
  93. EP250610A: Swift/UVOT Upper limits
  94. EP250610a: TNG NIR upper limit
  95. GRB 250610B: REM optical/NIR observations
  96. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  97. GRB 250610B: Swift-XRT counterpart detection
  98. GRB 250610B: SVOM/VT optical counterpart
  99. GRB 250610B: OHP/T120 optical counterpart candidate
  100. EP250610a: refined analysis of the EP-WXT and EP-FXT observations

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