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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"

18395 results found.

  1. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  2. GRB 241213A: SVOM/VT optical candidate
  3. GRB 241213B: Tiled Swift observations
  4. GRB 241213A: Swift/UVOT Upper Limits
  5. GRB 241213A: Swift-XRT refined Analysis
  6. GRB 241212A: Swift ToO observations
  7. GRB 241213A: LCOGT Optical Upper Limits
  8. EP241213a: EP detection of An X-ray Transient
  9. GRB 241213A: REM optical/NIR upper limits
  10. GRB 241213A: Enhanced Swift-XRT position
  11. Swift GRB 241213A: Global MASTER-Net observations report
  12. GRB 241213A: Swift detection of a burst
  13. GRB 241209A: Chandra X-ray Detection
  14. Konus-Wind detection of GRB 241209B
  15. GRB 241209B: GRBAlpha detection
  16. GRB 241129A: Fermi GBM Observation
  17. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  18. GRB 241209D: REM optical/NIR upper limits
  19. Konus-Wind detection of GRB 241209D
  20. GRB 241209B: Swift-XRT afterglow detection
  21. GRB 241209C: Fermi GBM Observation
  22. GRB 241209A: Swift-XRT refined Analysis
  23. GRB 241209D: AstroSat CZTI detection
  24. GRB 241209A: EP-FXT follow-up observations
  25. GRB 241209B: SVOM/VT afterglow detection
  26. GRB 241207B: Fermi GBM Observation
  27. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  28. GRB 241209D: Swift-XRT refined Analysis
  29. GRB 241209D: Fermi GBM Observation
  30. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  31. GRB 241209D: COLIBRÍ detection of the afterglow
  32. GRB 241209A: COLIBRÍ Optical Upper Limit
  33. GRB 241209A: Fermi GBM Observation
  34. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  35. GRB 241209A: GRANDMA/TAROT upper limit
  36. Swift GRB 241209D: Global MASTER-Net observations report
  37. GRB 241209B: Swift ToO observations
  38. GRB 241209A: REM optical/NIR observations
  39. GRB 241209D: Enhanced Swift-XRT position
  40. GRB 241209D: Swift detection of a burst
  41. GRB 241209A: Enhanced Swift-XRT position
  42. GRB 241209A: GOTO optical upper limits
  43. GRB 241209A: Prompt enhanced Swift-XRT position
  44. GRB 241209A: Swift detection of a short burst
  45. Swift GRB241209.23: Global MASTER-Net observations report
  46. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  47. GRB 241206A: DDOTI Upper Limit on the Afterglow
  48. GRB 241207C: Tiled Swift observations
  49. GRB 241206A: Fermi GBM observation
  50. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  51. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  52. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  53. GRB 241128A: Swift/UVOT Upper Limits
  54. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  55. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  56. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  57. GRB 241128A: Swift-BAT refined analysis
  58. GRB 241127A: Swift-BAT refined analysis
  59. GRB 241127A: PRIME near-infrared detection
  60. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  61. Swift-XRT observations of IceCube -241127A
  62. Swift GRB 241128A: Global MASTER-Net observations report
  63. GRB 241128A: Swift-XRT refined Analysis
  64. GRB 241128A: Enhanced Swift-XRT position
  65. GRB 241128A: 1.5m OSN optical afterglow detection
  66. GRB 241128A: Swift-XRT afterglow detection
  67. GRB 241128A: Swift detection of a burst
  68. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  69. GRB 241127A: Swift/UVOT Detection
  70. GRB 241127A: Swift-XRT refined Analysis
  71. GRB 241127A: SVOM/GRM observation
  72. GRB 241127A: Enhanced Swift-XRT position
  73. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  74. Swift GRB241127.91: Global MASTER-Net OT detection
  75. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  76. GRB 241127A: Swift detection of a burst with an optical counterpart
  77. Swift GRB241127.91: Global MASTER-Net observations report
  78. Swift GRB241127.91: Global MASTER-Net OT detection
  79. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  80. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  81. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  82. IPN triangulation of GRB 241114B
  83. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  84. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  85. Trigger_18947: Swift ToO observations (retracted)
  86. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  87. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  88. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  89. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  90. EP241125a: EP detection of an X-ray transient
  91. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  92. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  93. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  94. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  95. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  96. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  97. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  98. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  99. Konus-Wind detection of GRB 241117A
  100. IPN triangulation of GRB 241117A

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