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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').
  1. GRB 241016B: Fermi GBM Observations
  2. GRB 241018A: Detection of a bright long GRB by SVOM
  3. GRB 241017A: Swift-XRT observations
  4. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  5. GRB 241001A: EP-FXT afterglow detection
  6. GRB 241017A: GROWTH-India Telescope optical upper limit
  7. GRB241017A: TOO Observations by SVOM/MXT
  8. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  9. GRB 241017A: J-band upper limit from WINTER
  10. Fermi trigger No 750788395: Global MASTER-Net observations report
  11. GRB 241016B: SVOM/GRM observation
  12. GRB241016C: Fermi GBM Final Localization
  13. Fermi Gamma-ray Burst Monitor trigger 750792698/241016730 is not a GRB
  14. GRB 241017A: Swift ToO observations
  15. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  16. Fermi GRB 241016B: Global MASTER-Net observations report
  17. GRB 241016B: Fermi GBM Final Localization
  18. Fermi GRB 241016A: Global MASTER-Net observations report
  19. GRB 241016A: Fermi GBM Final Real-time Localization
  20. IceCube alert 139977_2910365 retraction
  21. IceCube Alert 241016.04: Global MASTER-Net observations report
  22. GRB 241010A: Swift-BAT refined analysis
  23. GRB 241013B: Fermi GBM Observation
  24. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  25. GRB 241013A: Fermi GBM Observation
  26. GRB 240916A: radio detection with the VLA
  27. GRB241013A: REM observations
  28. GRB 241009A: LCO optical upper limits
  29. GRB 241013B: SVOM/GRM observation
  30. Fermi GRB 241013B: Global MASTER-Net observations report
  31. Integral GRB241013.04: Global MASTER-Net observations report
  32. GRB 241013B: Fermi GBM Final Real-time Localization
  33. GRB 241013A: a long GRB detected by INTEGRAL
  34. GRB 241013A: Fermi GBM Final Real-time Localization
  35. LIGO/Virgo/KAGRA S241009em: Updated Sky localization
  36. LIGO/Virgo/KAGRA S241011k: Updated Sky localization
  37. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  38. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  39. Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
  40. GRB 241011A: Fermi GBM Final Real-time Localization
  41. GRB 241009A: GRANDMA optical upper limits
  42. GRB 241009A: Swift-XRT afterglow detection
  43. GRB 241010A: JinShan optical observations and potential host galaxy
  44. GRB 241006A: ATCA Radio Upper Limits
  45. GRB 241010A: Swift-XRT refined Analysis
  46. LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
  47. Fermi trigger No 750211959: Global MASTER-Net observations report
  48. Fermi Gamma-ray Burst Monitor trigger 750303285/241011066 is not a GRB
  49. Fermi Gamma-ray Burst Monitor trigger 750291012/241010924 is not a GRB
  50. Swift GRB 241010A: Global MASTER-Net observations report
  51. Fermi trigger No 750291012: Global MASTER-Net observations report
  52. GRB 241010A: J-band observations with WINTER
  53. LIGO/Virgo/KAGRA S241009an: Updated Sky localization
  54. Fermi GRB 241010B: Global MASTER-Net observations report
  55. GRB 241010B: Fermi GBM Final Real-time Localization
  56. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  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. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  64. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  65. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  66. GRB 241008A: Fermi GBM Observation
  67. GRB 241008A: Fermi-LAT detection
  68. GRB 241002B: Swift-XRT afterglow detection
  69. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  70. GRB 241002A: NOT optical upper limits
  71. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  72. Fermi GRB 241008A: Global MASTER-Net observations report
  73. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  74. GRB 241008A: Fermi GBM Final Real-time Localization
  75. IceCube-241006A: No candidates from the Zwicky Transient Facility
  76. GRB 241006A: GRANDMA optical upper limits
  77. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  78. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  79. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  80. GRB 240910A: LBT optical observations
  81. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  82. GRB 241006A: Swift-XRT refined Analysis
  83. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  84. GRB 241006A: PRIME near-infrared upper limits
  85. GRB 241006A: Swift/UVOT Upper Limits
  86. GRB 241006A: SVOM/VT follow-up and optical upper limit
  87. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  88. IceCube Alert 241006.94: Global MASTER-Net observations report
  89. GRB 241001A: Swift-XRT afterglow detection
  90. GRB 241006A: Enhanced Swift-XRT position
  91. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  92. GRB 241006A: Swift detection of a burst
  93. Swift GRB241006.91: Global MASTER-Net observations report
  94. GRB 240930B: SVOM/C-GFT optical upper limit
  95. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  97. Fermi trigger No 749721670: Global MASTER-Net observations report
  98. GRB 241004A: SVOM/GRM observation
  99. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  100. GRB 240930B / EP 240930a: SVOM/GRM observation

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