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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"

18397 results found.

  1. GRB 241212A: Swift-XRT observations
  2. GRB 241213B: Swift-XRT observations
  3. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  4. GRB 241213A: SVOM/VT optical candidate
  5. GRB 241213B: Tiled Swift observations
  6. GRB 241213A: Swift/UVOT Upper Limits
  7. GRB 241213A: Swift-XRT refined Analysis
  8. GRB 241212A: Swift ToO observations
  9. GRB 241213A: LCOGT Optical Upper Limits
  10. EP241213a: EP detection of An X-ray Transient
  11. GRB 241213A: REM optical/NIR upper limits
  12. GRB 241213A: Enhanced Swift-XRT position
  13. Swift GRB 241213A: Global MASTER-Net observations report
  14. GRB 241213A: Swift detection of a burst
  15. GRB 241209A: Chandra X-ray Detection
  16. Konus-Wind detection of GRB 241209B
  17. GRB 241209B: GRBAlpha detection
  18. GRB 241129A: Fermi GBM Observation
  19. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  20. GRB 241209D: REM optical/NIR upper limits
  21. Konus-Wind detection of GRB 241209D
  22. GRB 241209B: Swift-XRT afterglow detection
  23. GRB 241209C: Fermi GBM Observation
  24. GRB 241209A: Swift-XRT refined Analysis
  25. GRB 241209D: AstroSat CZTI detection
  26. GRB 241209A: EP-FXT follow-up observations
  27. GRB 241209B: SVOM/VT afterglow detection
  28. GRB 241207B: Fermi GBM Observation
  29. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  30. GRB 241209D: Swift-XRT refined Analysis
  31. GRB 241209D: Fermi GBM Observation
  32. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  33. GRB 241209D: COLIBRÍ detection of the afterglow
  34. GRB 241209A: COLIBRÍ Optical Upper Limit
  35. GRB 241209A: Fermi GBM Observation
  36. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  37. GRB 241209A: GRANDMA/TAROT upper limit
  38. Swift GRB 241209D: Global MASTER-Net observations report
  39. GRB 241209B: Swift ToO observations
  40. GRB 241209A: REM optical/NIR observations
  41. GRB 241209D: Enhanced Swift-XRT position
  42. GRB 241209D: Swift detection of a burst
  43. GRB 241209A: Enhanced Swift-XRT position
  44. GRB 241209A: GOTO optical upper limits
  45. GRB 241209A: Prompt enhanced Swift-XRT position
  46. GRB 241209A: Swift detection of a short burst
  47. Swift GRB241209.23: Global MASTER-Net observations report
  48. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  49. GRB 241206A: DDOTI Upper Limit on the Afterglow
  50. GRB 241207C: Tiled Swift observations
  51. GRB 241206A: Fermi GBM observation
  52. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  53. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  54. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  55. GRB 241128A: Swift/UVOT Upper Limits
  56. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  57. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  58. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  59. GRB 241128A: Swift-BAT refined analysis
  60. GRB 241127A: Swift-BAT refined analysis
  61. GRB 241127A: PRIME near-infrared detection
  62. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  63. Swift-XRT observations of IceCube -241127A
  64. Swift GRB 241128A: Global MASTER-Net observations report
  65. GRB 241128A: Swift-XRT refined Analysis
  66. GRB 241128A: Enhanced Swift-XRT position
  67. GRB 241128A: 1.5m OSN optical afterglow detection
  68. GRB 241128A: Swift-XRT afterglow detection
  69. GRB 241128A: Swift detection of a burst
  70. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  71. GRB 241127A: Swift/UVOT Detection
  72. GRB 241127A: Swift-XRT refined Analysis
  73. GRB 241127A: SVOM/GRM observation
  74. GRB 241127A: Enhanced Swift-XRT position
  75. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  76. Swift GRB241127.91: Global MASTER-Net OT detection
  77. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  78. GRB 241127A: Swift detection of a burst with an optical counterpart
  79. Swift GRB241127.91: Global MASTER-Net observations report
  80. Swift GRB241127.91: Global MASTER-Net OT detection
  81. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  82. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  83. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  84. IPN triangulation of GRB 241114B
  85. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  86. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  87. Trigger_18947: Swift ToO observations (retracted)
  88. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  89. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  90. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  91. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  92. EP241125a: EP detection of an X-ray transient
  93. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  94. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  95. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  96. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  97. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  98. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  99. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  100. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart

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