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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"

27774 results found.

  1. GRB 241026A: Fermi GBM Final Real-time Localization
  2. GRB241025A: 1.3m DFOT optical afterglow detection
  3. EP241021a: optical follow-up observations with Xinglong Observatory
  4. ​GRB 241025A: optical photometry from Konkoly
  5. GRB 241025A: GROWTH-India Telescope optical observations
  6. GRB 241025A: COLIBRÍ Detection of the Afterglow
  7. GRB 241025A: Swift-XRT refined Analysis
  8. GRB 241025C: Fermi GBM Detection
  9. GRB 241025A: Fermi GBM Observation
  10. IPN triangulation of GRB 241022A (short/hard)
  11. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  12. GRB 241025C: Fermi GBM Final Localization
  13. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  14. GRB 241025B: Fermi GBM Final Localization
  15. EP 241021a: Swift-XRT observations
  16. Swift GRB 241025A: Global MASTER-Net observations report
  17. EP241025a (GRB 241025A): EP observations update
  18. EP 241021A: Swift ToO observations
  19. EP241021a: Liverpool Telescope optical follow-up observations
  20. GRB 241025A: Enhanced Swift-XRT position
  21. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  22. GRB 241025A: DDOTI Afterglow detection
  23. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  24. GRB 241025A: SVOM/GRM observation
  25. GRB 241025A: TRT optical afterglow observation
  26. GRB 241025A: Fermi GBM Final Real-time Localization
  27. GRB 241025A: Swift detection of a burst with an optical counterpart
  28. GRB 241001A: ATCA radio observations
  29. GRB 241024B: Fermi GBM Final Localization
  30. EP241021a: No Detection in Fermi-GBM Observation
  31. GRB 241010A: VIRT Optical Upper Limit
  32. GRB 241024A: Fermi GBM Final Localisation
  33. EP241021a: VLT/FORS2 redshift z = 0.75
  34. EP241021a: EP-FXT follow-up observation update
  35. EP241021a: Optical counterpart observations with the Liverpool Telescope
  36. EP241021a: 1.3m DFOT Optical observations
  37. EP241021a: NOT likely optical counterpart
  38. GRB241017A: 1.3m DFOT optical upper limit
  39. GRB 241018A: 1.3m DFOT Optical upper limit
  40. GRB 241018A: EP-FXT afterglow detection
  41. EP241021a: EP detection of a fast X-ray transient
  42. Konus-Wind detection of GRB 241018A
  43. GRB 241018A: BOOTES-4/MET optical upper limit
  44. GRB 241018A: Mondy optical upper limit
  45. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  46. GRB 241018A: GROWTH-India telescope optical upper limit
  47. GRB 241018A: Swift-XRT observations
  48. GRB 241018A: NOT optical observations
  49. GRB 241018A: Swift ToO observations
  50. GRB 241006A: VIRT Optical Upper Limit
  51. GRB 240727A: VIRT Optical Upper Limit
  52. GRB 241018A: X-ray afterglow candidate observed by MXT
  53. GRB 241016B: Fermi GBM Observations
  54. GRB 241018A: Detection of a bright long GRB by SVOM
  55. GRB 241017A: Swift-XRT observations
  56. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  57. GRB 241001A: EP-FXT afterglow detection
  58. GRB 241017A: GROWTH-India Telescope optical upper limit
  59. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  60. GRB241016C: Fermi GBM Final Localization
  61. GRB 241017A: Swift ToO observations
  62. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  63. GRB 241016B: Fermi GBM Final Localization
  64. GRB 241016A: Fermi GBM Final Real-time Localization
  65. IceCube alert 139977_2910365 retraction
  66. GRB 241010A: Swift-BAT refined analysis
  67. GRB 241013B: Fermi GBM Observation
  68. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  69. GRB 240916A: radio detection with the VLA
  70. GRB 241009A: LCO optical upper limits
  71. GRB 241013B: Fermi GBM Final Real-time Localization
  72. GRB 241013A: Fermi GBM Final Real-time Localization
  73. GRB 241011A: Fermi GBM Final Real-time Localization
  74. GRB 241009A: GRANDMA optical upper limits
  75. GRB 241009A: Swift-XRT afterglow detection
  76. GRB 241010A: JinShan optical observations and potential host galaxy
  77. GRB 241006A: ATCA Radio Upper Limits
  78. GRB 241010A: Swift-XRT refined Analysis
  79. Swift GRB 241010A: Global MASTER-Net observations report
  80. GRB 241010A: J-band observations with WINTER
  81. GRB 241010B: Fermi GBM Final Real-time Localization
  82. GRB 241010A: Enhanced Swift-XRT position
  83. GRB 241010A: LCO optical observations
  84. GRB 241010A: Swift detection of a burst with an optical counterpart
  85. GRB 241006A: Swift-BAT refined analysis
  86. GRB 241009A: Swift ToO observations
  87. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  88. GRB 241008A: Fermi-LAT detection
  89. GRB 241002B: Swift-XRT afterglow detection
  90. GRB 241002A: NOT optical upper limits
  91. GRB 241008A: Fermi GBM Final Real-time Localization
  92. IceCube-241006A: No candidates from the Zwicky Transient Facility
  93. GRB 241006A: GRANDMA optical upper limits
  94. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  95. GRB 241006A: Swift-XRT refined Analysis
  96. GRB 241006A: PRIME near-infrared upper limits
  97. GRB 241006A: Swift/UVOT Upper Limits
  98. GRB 241006A: SVOM/VT follow-up and optical upper limit
  99. GRB 241001A: Swift-XRT afterglow detection
  100. GRB 241006A: Enhanced Swift-XRT position

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