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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

"200205A/SWIFT J0840.7-3516" does not adhere to advanced search syntax. Please refer to the documentation and try again.
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"

19596 results found.

  1. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  2. Swift GRB250612.04: Global MASTER-Net observations report
  3. GRB 250610B: Swift/UVOT Detection
  4. EP250610A: Swift/UVOT Upper limits
  5. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  6. GRB 250610B: Swift-XRT counterpart detection
  7. GRB 250610B: SVOM/VT optical counterpart
  8. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  9. GRB 250605A: Swift-BAT refined analysis
  10. EP250610a: SVOM/VT optical upper limit
  11. EP250610a: REM optical/NIR observations
  12. GRB 250609A: Fermi GBM Observation
  13. EP250610a: Swift-XRT counterpart detection
  14. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  15. GRB 250605A: Swift/UVOT Upper Limits
  16. GRB 250527C: CrAO Optical Upper Limit
  17. GRB 250605A: SVOM/VT optical upper limit
  18. GRB 250605A: Swift-XRT refined Analysis
  19. GRB 250605A: Enhanced Swift-XRT position
  20. GRB 250605A: LT optical observations
  21. GRB 250605A: Swift detection of a burst
  22. Swift GRB250605.79: Global MASTER-Net observations report
  23. Konus-Wind detection of GRB 250601A
  24. IPN triangulation of GRB 250404B
  25. IPN triangulation of GRB 250529A
  26. GRB 250601A: PRIME H band upper limit.
  27. GRB 250601A: PRIME J band upper limit.
  28. GRB 250601A: VLT/FORS2 Optical Observation
  29. GRB 250601A: Fermi GBM Observation
  30. GRB 250603A: Swift/UVOT Upper Limits
  31. GRB 250603A: Swift-XRT refined Analysis
  32. GRB 250603A: Enhanced Swift-XRT position
  33. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  34. Swift GRB250603.05: Global MASTER-Net observations report
  35. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  36. GRB 250530C: Swift-BAT refined analysis
  37. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  38. GRB 250601A: Swift/XRT candidate afterglow
  39. GRB 250601A: Swift-XRT observations
  40. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  41. GRB 250601A: Swift ToO observations
  42. EP#01709177494: SVOM/VT optical observations
  43. EP#01709177494: Swift-XRT counterpart detection of known source
  44. GRB 250530C: BOOTES-7 optical upper limit
  45. GRB 250530C: Swift-XRT refined Analysis
  46. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  47. Swift GRB 250530C: Global MASTER-Net observations report
  48. GRB 250530C: Enhanced Swift-XRT position
  49. GRB 250530C: Swift detection of a burst
  50. GRB 250530A: EP-FXT counterpart detection
  51. GRB 250530A: SVOM/VT optical upper limit
  52. GRB 250530A: Swift-XRT counterpart detection
  53. GRB 250527D: CALET Gamma-Ray Burst Monitor detection
  54. GRB 250527C: Swift/UVOT Upper Limits
  55. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  56. GRB 250527B: Swift-XRT observations
  57. GRB 250520A: Swift-BAT refined analysis
  58. GRB 250527C: Swift ToO observations
  59. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  60. GRB 250527B: Tiled Swift observations
  61. GRB 250520A: GRBAlpha detection
  62. GRB 250521B: SVOM/VT optical upper limit
  63. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  64. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  65. EP#01709176612: Swift-XRT counterpart detection of flaring star
  66. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 250521B: Swift ToO observations
  68. Konus-Wind detection of GRB 250520A (short/hard)
  69. GRB 250520A: Swift/UVOT Upper Limits
  70. IPN triangulation of GRB 250516B
  71. GRB 250520A: J-band observations with WINTER
  72. GRB 250520A: Swift-XRT refined Analysis
  73. GRB 250520A: REM optical/NIR early observations
  74. GRB 250520A：SVOM/VT optical candidate
  75. GRB 250520A: COLIBRÍ optical upper limit
  76. GRB 250520A: DDOTI Optical Upper Limit
  77. GRB 250520A: AstroSat CZTI detection of a short burst
  78. GRB 250520A: SVOM/GRM observation
  79. GRB 250520A: Enhanced Swift-XRT position
  80. GRB 250520A: GOTO optical upper limit
  81. GRB 250520A: Prompt enhanced Swift-XRT position
  82. GRB 250520A: Swift detection of a burst
  83. Swift GRB 250520A: Global MASTER-Net observations report
  84. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  85. GRB 250516A: Swift-BAT refined analysis
  86. Konus-Wind detection of GRB 250516A
  87. GRB 250515A: Swift-XRT observations
  88. Swift GRB 250516A: Global MASTER-Net observations report
  89. GRB 250516A: AstroSat CZTI detection
  90. GRB 250516A: Fermi GBM Observation
  91. GRB 250516A: Swift-XRT refined Analysis
  92. GRB 250516A: Swift/UVOT Detection
  93. GRB 250515A: Swift ToO observations
  94. GRB 250516A: Enhanced Swift-XRT position
  95. GRB 250516A: Swift detection of a burst
  96. GRB 250509A: Swift-BAT refined analysis
  97. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  98. GRB 250510B: Fermi GBM Observation
  99. GRB 250510A: Swift-XRT observations
  100. GRB 250509A: Fermi GBM Observation

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