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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"
  1. EP240816a: BOOTES-6/DPRT optical upper limit
  2. GRB 240815A: SVOM/GRM observation
  3. GRB 240817A: Fermi GBM Final Real-time Localization
  4. Integral GRB240816.79: Global MASTER-Net observations report
  5. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  6. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  7. IBAS Alert n.10856: not a GRB
  8. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  9. EP240816b: KAIT optical upper limit
  10. GRB 240814B: GRBAlpha detection
  11. Fermi trigger No 745501396: Global MASTER-Net observations report
  12. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  13. EP EP240816b: Global MASTER-Net observations report
  14. EP240816b: TRT optical upper limit
  15. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  16. Fermi GRB 240814A: Global MASTER-Net observations report
  17. Fermi GRB 240814C: Global MASTER-Net observations report
  18. Fermi trigger No 745306088: Global MASTER-Net observations report
  19. GRB 240814C: Fermi GBM Final Real-time Localization
  20. Fermi GRB 240814B: Global MASTER-Net observations report
  21. GRB 240812B: SVOM/GRM observation
  22. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  23. GRB 240814B: Fermi GBM Final Real-time Localization
  24. GRB 240814A: Fermi GBM Final Real-time Localization
  25. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  26. Fermi trigger No 745220784: Global MASTER-Net observations report
  27. Konus-Wind detection of GRB 240811A
  28. Konus-Wind detection of GRB 240810A
  29. Fermi Gamma-ray Burst Monitor trigger 745220784/240813240 is not a GRB
  30. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  32. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  33. GRB 240809A: Correction to the VLA source position in GCN 37158
  34. GRB 240810A: SVOM/GRM observation
  35. Fermi Gamma-ray Burst Monitor trigger 240812940/745194848 is not a GRB
  36. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  37. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  38. GRB 240809A: ATA radio non-detection
  39. GRB 240812D: Fermi GBM Final Real-time Localization
  40. GRB 240812C: Fermi GBM Final Real-time Localization
  41. GRB 240809A : RAPAS follow-up observations
  42. GRB 240809A: VLA detection
  43. GRB 240809A: ALMA detection
  44. IPN triangulation of GRB 240810A (short)
  45. GRB 240811A: Swift-BAT refined analysis
  46. GRB 240809A: Swift-BAT refined analysis
  47. EP240807a: PRIME H-band upper limits
  48. GRB 240812B: AstroSat CZTI detection of a long burst
  49. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  50. GRB 240811A: Bassano Bresciano Observatory upper limit
  51. GRB 240811A: Swift-XRT refined Analysis
  52. Fermi Gamma-ray Burst Monitor trigger 745135620/240812255 is not a GRB
  53. GRB 240811A: Swift/UVOT Upper Limits
  54. EP240801a: Assy-Turgen optical observations
  55. Fermi GRB 240810A: Global MASTER-Net observations report
  56. Fermi Gamma-ray Burst Monitor trigger 240812094/745121685 is not a GRB
  57. GRB 240812A: Fermi GBM Final Real-time Localization
  58. GRB 240811A: LCOGT Optical Upper Limit
  59. GRB 240811A: Enhanced Swift-XRT position
  60. GRB 240811A: Upper limits with Mephisto
  61. Konus-Wind detection of GRB 240809A
  62. Fermi trigger No 745057312: Global MASTER-Net observations report
  63. Swift GRB 240811A: Global MASTER-Net observations report
  64. GRB 240811A: Swift detection of a burst
  65. Fermi Gamma-ray Burst Monitor trigger 745050426/240811269 is not a GRB
  66. GRB240809A: Liverpool Telescope optical follow-up observations
  67. GRB 240810A: Fermi GBM Final Real-time Localization
  68. GRB 240809A: REM detection of the optical afterglow
  69. GRB 240809A: Bassano Bresciano Observatory optical observations
  70. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  71. GRB 240809A: Conclusive redshift from VLT
  72. Fermi-LAT gamma-ray observations of IceCube-240808A
  73. GRB 240809A: KAIT optical observations
  74. GRB 240808A: AstroSat CZTI detection
  75. GRB 240809A: GIT afterglow observations
  76. GRB 240809B: MAXI/GSC detection
  77. GRB 240809A: Swift/UVOT Detection
  78. GRB 240809A: Tentative redshift from NOT
  79. GRB 240809A: Swift-XRT refined Analysis
  80. IPN triangulation of GRB 240807A / EP 240807a
  81. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  82. X-ray Transient EP240807a: PRIME near-infrared upper limits
  83. Swift GRB 240809A: Global MASTER-Net observations report
  84. GRB 240809A: JinShan optical observations
  85. GRB 240809A: Enhanced Swift-XRT position
  86. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  87. GRB 240809A: SVOM/GRM observation
  88. GRB 240808A: SVOM/GRM observation
  89. GRB 240807A: SVOM/GRM observation
  90. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  91. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  92. EP240807a: STEP/T80S optical limits
  93. GRB 240807B: AstroSat CZTI detection of a short burst
  94. IceCube Alert 240808.27: Global MASTER-Net observations report
  95. EP EP240807a: Global MASTER-Net observations report
  96. EP EP240806a: Global MASTER-Net observations report
  97. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  98. GRB 240801A: GRBAlpha detection
  99. GRB 240807B: Fermi GBM Final Localization
  100. GRB 240710B: VZLUSAT-2 detection

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