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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"

38282 results found.

  1. GRB 241018A: Swift-XRT observations
  2. GRB 241018A: REM optical/NIR upper limits
  3. GRB 241018A: NOT optical observations
  4. GRB 241017A: SVOM/VT follow-up and optical upper limit
  5. GRB 241018A: SVOM/VT follow-up and optical candidate
  6. GRB 241018A: LCO/0.4m optical upper limits
  7. GRB 241018A: Swift ToO observations
  8. GRB 241006A: VIRT Optical Upper Limit
  9. GRB 240727A: VIRT Optical Upper Limit
  10. GRB 241018A: X-ray afterglow candidate observed by MXT
  11. GRB 241016B: Fermi GBM Observations
  12. GRB 241018A: Detection of a bright long GRB by SVOM
  13. GRB 241017A: Swift-XRT observations
  14. GRB 241001A: EP-FXT afterglow detection
  15. GRB 241017A: GROWTH-India Telescope optical upper limit
  16. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  17. GRB 241017A: J-band upper limit from WINTER
  18. Fermi trigger No 750788395: Global MASTER-Net observations report
  19. GRB 241016B: SVOM/GRM observation
  20. GRB241016C: Fermi GBM Final Localization
  21. Fermi Gamma-ray Burst Monitor trigger 750792698/241016730 is not a GRB
  22. GRB 241017A: Swift ToO observations
  23. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  24. Fermi GRB 241016B: Global MASTER-Net observations report
  25. GRB 241016B: Fermi GBM Final Localization
  26. Fermi GRB 241016A: Global MASTER-Net observations report
  27. GRB 241016A: Fermi GBM Final Real-time Localization
  28. IceCube Alert 241016.04: Global MASTER-Net observations report
  29. GRB 241010A: Swift-BAT refined analysis
  30. GRB 241013B: Fermi GBM Observation
  31. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  32. GRB 241013A: Fermi GBM Observation
  33. GRB 240916A: radio detection with the VLA
  34. GRB241013A: REM observations
  35. GRB 241009A: LCO optical upper limits
  36. GRB 241013B: SVOM/GRM observation
  37. Fermi GRB 241013B: Global MASTER-Net observations report
  38. Integral GRB241013.04: Global MASTER-Net observations report
  39. GRB 241013B: Fermi GBM Final Real-time Localization
  40. GRB 241013A: a long GRB detected by INTEGRAL
  41. GRB 241013A: Fermi GBM Final Real-time Localization
  42. Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
  43. GRB 241011A: Fermi GBM Final Real-time Localization
  44. GRB 241009A: GRANDMA optical upper limits
  45. GRB 241009A: Swift-XRT afterglow detection
  46. GRB 241010A: JinShan optical observations and potential host galaxy
  47. GRB 241006A: ATCA Radio Upper Limits
  48. GRB 241010A: Swift-XRT refined Analysis
  49. Fermi trigger No 750211959: Global MASTER-Net observations report
  50. Fermi Gamma-ray Burst Monitor trigger 750303285/241011066 is not a GRB
  51. Fermi Gamma-ray Burst Monitor trigger 750291012/241010924 is not a GRB
  52. Swift GRB 241010A: Global MASTER-Net observations report
  53. Fermi trigger No 750291012: Global MASTER-Net observations report
  54. GRB 241010A: J-band observations with WINTER
  55. Fermi GRB 241010B: Global MASTER-Net observations report
  56. GRB 241010B: Fermi GBM Final Real-time Localization
  57. GRB 241010A: Enhanced Swift-XRT position
  58. GRB 241010A: LCO optical observations
  59. GRB 241010A: Swift detection of a burst with an optical counterpart
  60. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  61. GRB 241006A: Swift-BAT refined analysis
  62. GRB 241009A: Swift ToO observations
  63. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  64. GRB 241008A: Fermi GBM Observation
  65. GRB 241008A: Fermi-LAT detection
  66. GRB 241002B: Swift-XRT afterglow detection
  67. GRB 241002A: NOT optical upper limits
  68. Fermi GRB 241008A: Global MASTER-Net observations report
  69. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  70. GRB 241008A: Fermi GBM Final Real-time Localization
  71. GRB 241006A: GRANDMA optical upper limits
  72. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  73. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  74. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  75. GRB 240910A: LBT optical observations
  76. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  77. GRB 241006A: Swift-XRT refined Analysis
  78. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  79. GRB 241006A: PRIME near-infrared upper limits
  80. GRB 241006A: Swift/UVOT Upper Limits
  81. GRB 241006A: SVOM/VT follow-up and optical upper limit
  82. IceCube Alert 241006.94: Global MASTER-Net observations report
  83. GRB 241001A: Swift-XRT afterglow detection
  84. GRB 241006A: Enhanced Swift-XRT position
  85. GRB 241006A: Swift detection of a burst
  86. Swift GRB241006.91: Global MASTER-Net observations report
  87. GRB 240930B: SVOM/C-GFT optical upper limit
  88. Fermi trigger No 749721670: Global MASTER-Net observations report
  89. GRB 241004A: SVOM/GRM observation
  90. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  91. GRB 240930B / EP 240930a: SVOM/GRM observation
  92. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  93. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  94. GRB 241002B: Fermi GBM Observation
  95. Fermi trigger No 749735279: Global MASTER-Net observations report
  96. Fermi trigger No 749630753: Global MASTER-Net observations report
  97. Fermi trigger No 749693019: Global MASTER-Net observations report
  98. GRB 241002B: Swift-XRT observations
  99. GRB 241002C: SVOM/C-GFT optical upper limit
  100. GRB 241002A: Swift-BAT refined analysis

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