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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. GRB 240817A: Fermi GBM Final Real-time Localization
  2. Integral GRB240816.79: Global MASTER-Net observations report
  3. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  4. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  5. IBAS Alert n.10856: not a GRB
  6. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  7. EP240816b: KAIT optical upper limit
  8. GRB 240814B: GRBAlpha detection
  9. Fermi trigger No 745501396: Global MASTER-Net observations report
  10. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  11. EP EP240816b: Global MASTER-Net observations report
  12. EP240816b: TRT optical upper limit
  13. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  14. Fermi GRB 240814A: Global MASTER-Net observations report
  15. Fermi GRB 240814C: Global MASTER-Net observations report
  16. Fermi trigger No 745306088: Global MASTER-Net observations report
  17. GRB 240814C: Fermi GBM Final Real-time Localization
  18. Fermi GRB 240814B: Global MASTER-Net observations report
  19. GRB 240812B: SVOM/GRM observation
  20. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  21. GRB 240814B: Fermi GBM Final Real-time Localization
  22. GRB 240814A: Fermi GBM Final Real-time Localization
  23. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  24. Fermi trigger No 745220784: Global MASTER-Net observations report
  25. Konus-Wind detection of GRB 240811A
  26. Konus-Wind detection of GRB 240810A
  27. Fermi Gamma-ray Burst Monitor trigger 745220784/240813240 is not a GRB
  28. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  30. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  31. GRB 240809A: Correction to the VLA source position in GCN 37158
  32. GRB 240810A: SVOM/GRM observation
  33. Fermi Gamma-ray Burst Monitor trigger 240812940/745194848 is not a GRB
  34. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  35. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  36. GRB 240809A: ATA radio non-detection
  37. GRB 240812D: Fermi GBM Final Real-time Localization
  38. GRB 240812C: Fermi GBM Final Real-time Localization
  39. GRB 240809A : RAPAS follow-up observations
  40. GRB 240809A: VLA detection
  41. GRB 240809A: ALMA detection
  42. IPN triangulation of GRB 240810A (short)
  43. GRB 240811A: Swift-BAT refined analysis
  44. GRB 240809A: Swift-BAT refined analysis
  45. EP240807a: PRIME H-band upper limits
  46. GRB 240812B: AstroSat CZTI detection of a long burst
  47. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 240811A: Bassano Bresciano Observatory upper limit
  49. GRB 240811A: Swift-XRT refined Analysis
  50. Fermi Gamma-ray Burst Monitor trigger 745135620/240812255 is not a GRB
  51. GRB 240811A: Swift/UVOT Upper Limits
  52. EP240801a: Assy-Turgen optical observations
  53. Fermi GRB 240810A: Global MASTER-Net observations report
  54. Fermi Gamma-ray Burst Monitor trigger 240812094/745121685 is not a GRB
  55. GRB 240812A: Fermi GBM Final Real-time Localization
  56. GRB 240811A: LCOGT Optical Upper Limit
  57. GRB 240811A: Enhanced Swift-XRT position
  58. GRB 240811A: Upper limits with Mephisto
  59. Konus-Wind detection of GRB 240809A
  60. Fermi trigger No 745057312: Global MASTER-Net observations report
  61. Swift GRB 240811A: Global MASTER-Net observations report
  62. GRB 240811A: Swift detection of a burst
  63. Fermi Gamma-ray Burst Monitor trigger 745050426/240811269 is not a GRB
  64. GRB240809A: Liverpool Telescope optical follow-up observations
  65. GRB 240810A: Fermi GBM Final Real-time Localization
  66. GRB 240809A: REM detection of the optical afterglow
  67. GRB 240809A: Bassano Bresciano Observatory optical observations
  68. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  69. GRB 240809A: Conclusive redshift from VLT
  70. Fermi-LAT gamma-ray observations of IceCube-240808A
  71. GRB 240809A: KAIT optical observations
  72. GRB 240808A: AstroSat CZTI detection
  73. GRB 240809A: GIT afterglow observations
  74. GRB 240809B: MAXI/GSC detection
  75. GRB 240809A: Swift/UVOT Detection
  76. GRB 240809A: Tentative redshift from NOT
  77. GRB 240809A: Swift-XRT refined Analysis
  78. IPN triangulation of GRB 240807A / EP 240807a
  79. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  80. X-ray Transient EP240807a: PRIME near-infrared upper limits
  81. Swift GRB 240809A: Global MASTER-Net observations report
  82. GRB 240809A: JinShan optical observations
  83. GRB 240809A: Enhanced Swift-XRT position
  84. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  85. GRB 240809A: SVOM/GRM observation
  86. GRB 240808A: SVOM/GRM observation
  87. GRB 240807A: SVOM/GRM observation
  88. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  89. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  90. EP240807a: STEP/T80S optical limits
  91. GRB 240807B: AstroSat CZTI detection of a short burst
  92. IceCube Alert 240808.27: Global MASTER-Net observations report
  93. EP EP240807a: Global MASTER-Net observations report
  94. EP EP240806a: Global MASTER-Net observations report
  95. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 240801A: GRBAlpha detection
  97. GRB 240807B: Fermi GBM Final Localization
  98. GRB 240710B: VZLUSAT-2 detection
  99. GRB 240805A: ATCA Radio Upper Limits
  100. Fermi trigger No 744761058: Global MASTER-Net observations report

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