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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"

19597 results found.

  1. GRB 241213A: Swift-XRT refined Analysis
  2. GRB 241212A: Swift ToO observations
  3. GRB 241213A: LCOGT Optical Upper Limits
  4. EP241213a: EP detection of An X-ray Transient
  5. GRB 241213A: REM optical/NIR upper limits
  6. GRB 241213A: Enhanced Swift-XRT position
  7. Swift GRB 241213A: Global MASTER-Net observations report
  8. GRB 241213A: Swift detection of a burst
  9. GRB 241209A: Chandra X-ray Detection
  10. Konus-Wind detection of GRB 241209B
  11. GRB 241209B: GRBAlpha detection
  12. GRB 241129A: Fermi GBM Observation
  13. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  14. GRB 241209D: REM optical/NIR upper limits
  15. Konus-Wind detection of GRB 241209D
  16. GRB 241209B: Swift-XRT afterglow detection
  17. GRB 241209C: Fermi GBM Observation
  18. GRB 241209A: Swift-XRT refined Analysis
  19. GRB 241209D: AstroSat CZTI detection
  20. GRB 241209A: EP-FXT follow-up observations
  21. GRB 241209B: SVOM/VT afterglow detection
  22. GRB 241207B: Fermi GBM Observation
  23. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  24. GRB 241209D: Swift-XRT refined Analysis
  25. GRB 241209D: Fermi GBM Observation
  26. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  27. GRB 241209D: COLIBRÍ detection of the afterglow
  28. GRB 241209A: COLIBRÍ Optical Upper Limit
  29. GRB 241209A: Fermi GBM Observation
  30. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  31. GRB 241209A: GRANDMA/TAROT upper limit
  32. Swift GRB 241209D: Global MASTER-Net observations report
  33. GRB 241209B: Swift ToO observations
  34. GRB 241209A: REM optical/NIR observations
  35. GRB 241209D: Enhanced Swift-XRT position
  36. GRB 241209D: Swift detection of a burst
  37. GRB 241209A: Enhanced Swift-XRT position
  38. GRB 241209A: GOTO optical upper limits
  39. GRB 241209A: Prompt enhanced Swift-XRT position
  40. GRB 241209A: Swift detection of a short burst
  41. Swift GRB241209.23: Global MASTER-Net observations report
  42. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  43. GRB 241206A: DDOTI Upper Limit on the Afterglow
  44. GRB 241207C: Tiled Swift observations
  45. GRB 241206A: Fermi GBM observation
  46. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  47. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  48. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  49. GRB 241128A: Swift/UVOT Upper Limits
  50. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  51. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  52. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  53. GRB 241128A: Swift-BAT refined analysis
  54. GRB 241127A: Swift-BAT refined analysis
  55. GRB 241127A: PRIME near-infrared detection
  56. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  57. Swift-XRT observations of IceCube -241127A
  58. Swift GRB 241128A: Global MASTER-Net observations report
  59. GRB 241128A: Swift-XRT refined Analysis
  60. GRB 241128A: Enhanced Swift-XRT position
  61. GRB 241128A: 1.5m OSN optical afterglow detection
  62. GRB 241128A: Swift-XRT afterglow detection
  63. GRB 241128A: Swift detection of a burst
  64. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  65. GRB 241127A: Swift/UVOT Detection
  66. GRB 241127A: Swift-XRT refined Analysis
  67. GRB 241127A: SVOM/GRM observation
  68. GRB 241127A: Enhanced Swift-XRT position
  69. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  70. Swift GRB241127.91: Global MASTER-Net OT detection
  71. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  72. GRB 241127A: Swift detection of a burst with an optical counterpart
  73. Swift GRB241127.91: Global MASTER-Net observations report
  74. Swift GRB241127.91: Global MASTER-Net OT detection
  75. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  76. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  77. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  78. IPN triangulation of GRB 241114B
  79. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  80. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  81. Trigger_18947: Swift ToO observations (retracted)
  82. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  83. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  84. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  85. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  86. EP241125a: EP detection of an X-ray transient
  87. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  88. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  89. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  90. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  91. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  92. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  93. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  94. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  95. Konus-Wind detection of GRB 241117A
  96. IPN triangulation of GRB 241117A
  97. GRB 241025A: VIRT Optical Upper Limit
  98. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 241115a: PRIME near-infrared upper limits
  100. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst

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