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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.

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"

19604 results found.

  1. EP241217a: Swift-XRT Detection
  2. GRB 241214A: GRBAlpha detection
  3. GRB 241213A (EP241213a): GRBAlpha detection
  4. GRB 241209D: GRBAlpha detection
  5. GRB 241213A: Swift-BAT refined analysis
  6. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  7. Konus-Wind detection of GRB 241213A (EP 241213a)
  8. GRB 241212A: Swift-XRT observations
  9. GRB 241213B: Swift-XRT observations
  10. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  11. GRB 241213A: SVOM/VT optical candidate
  12. GRB 241213B: Tiled Swift observations
  13. GRB 241213A: Swift/UVOT Upper Limits
  14. GRB 241213A: Swift-XRT refined Analysis
  15. GRB 241212A: Swift ToO observations
  16. GRB 241213A: LCOGT Optical Upper Limits
  17. EP241213a: EP detection of An X-ray Transient
  18. GRB 241213A: REM optical/NIR upper limits
  19. GRB 241213A: Enhanced Swift-XRT position
  20. Swift GRB 241213A: Global MASTER-Net observations report
  21. GRB 241213A: Swift detection of a burst
  22. GRB 241209A: Chandra X-ray Detection
  23. Konus-Wind detection of GRB 241209B
  24. GRB 241209B: GRBAlpha detection
  25. GRB 241129A: Fermi GBM Observation
  26. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  27. GRB 241209D: REM optical/NIR upper limits
  28. Konus-Wind detection of GRB 241209D
  29. GRB 241209B: Swift-XRT afterglow detection
  30. GRB 241209C: Fermi GBM Observation
  31. GRB 241209A: Swift-XRT refined Analysis
  32. GRB 241209D: AstroSat CZTI detection
  33. GRB 241209A: EP-FXT follow-up observations
  34. GRB 241209B: SVOM/VT afterglow detection
  35. GRB 241207B: Fermi GBM Observation
  36. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  37. GRB 241209D: Swift-XRT refined Analysis
  38. GRB 241209D: Fermi GBM Observation
  39. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  40. GRB 241209D: COLIBRÍ detection of the afterglow
  41. GRB 241209A: COLIBRÍ Optical Upper Limit
  42. GRB 241209A: Fermi GBM Observation
  43. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  44. GRB 241209A: GRANDMA/TAROT upper limit
  45. Swift GRB 241209D: Global MASTER-Net observations report
  46. GRB 241209B: Swift ToO observations
  47. GRB 241209A: REM optical/NIR observations
  48. GRB 241209D: Enhanced Swift-XRT position
  49. GRB 241209D: Swift detection of a burst
  50. GRB 241209A: Enhanced Swift-XRT position
  51. GRB 241209A: GOTO optical upper limits
  52. GRB 241209A: Prompt enhanced Swift-XRT position
  53. GRB 241209A: Swift detection of a short burst
  54. Swift GRB241209.23: Global MASTER-Net observations report
  55. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  56. GRB 241206A: DDOTI Upper Limit on the Afterglow
  57. GRB 241207C: Tiled Swift observations
  58. GRB 241206A: Fermi GBM observation
  59. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  60. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  61. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  62. GRB 241128A: Swift/UVOT Upper Limits
  63. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  64. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  65. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  66. GRB 241128A: Swift-BAT refined analysis
  67. GRB 241127A: Swift-BAT refined analysis
  68. GRB 241127A: PRIME near-infrared detection
  69. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  70. Swift-XRT observations of IceCube -241127A
  71. Swift GRB 241128A: Global MASTER-Net observations report
  72. GRB 241128A: Swift-XRT refined Analysis
  73. GRB 241128A: Enhanced Swift-XRT position
  74. GRB 241128A: 1.5m OSN optical afterglow detection
  75. GRB 241128A: Swift-XRT afterglow detection
  76. GRB 241128A: Swift detection of a burst
  77. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  78. GRB 241127A: Swift/UVOT Detection
  79. GRB 241127A: Swift-XRT refined Analysis
  80. GRB 241127A: SVOM/GRM observation
  81. GRB 241127A: Enhanced Swift-XRT position
  82. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  83. Swift GRB241127.91: Global MASTER-Net OT detection
  84. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  85. GRB 241127A: Swift detection of a burst with an optical counterpart
  86. Swift GRB241127.91: Global MASTER-Net observations report
  87. Swift GRB241127.91: Global MASTER-Net OT detection
  88. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  89. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  90. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  91. IPN triangulation of GRB 241114B
  92. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  93. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  94. Trigger_18947: Swift ToO observations (retracted)
  95. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  96. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  97. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  98. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  99. EP241125a: EP detection of an X-ray transient
  100. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position

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