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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. Trigger 1249653: Swift detection of SGR 1E 1841-045 / Kes 73
  2. Fermi trigger No 745873283: Global MASTER-Net observations report
  3. Fermi trigger No 745871958: Global MASTER-Net observations report
  4. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  5. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  6. GRB 240819A: X-ray follow-up observation with EP-FXT
  7. Fermi Gamma-ray Burst Monitor trigger 745811685 / 240820080 is not a GRB
  8. GRB 240820A: Fermi GBM Final Real-time Localization
  9. GRB 240819A: Swift ToO observations
  10. GRB 240814A: SVOM/GRM observation
  11. EP240816b: Liverpool Telescope optical follow-up observations
  12. GRB 240814C: SVOM/GRM observation
  13. EP240816a: BOOTES-6/DPRT optical upper limit
  14. GRB 240815A: SVOM/GRM observation
  15. GRB 240817A: Fermi GBM Final Real-time Localization
  16. Integral GRB240816.79: Global MASTER-Net observations report
  17. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  18. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  19. IBAS Alert n.10856: not a GRB
  20. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  21. EP240816b: KAIT optical upper limit
  22. GRB 240814B: GRBAlpha detection
  23. Fermi trigger No 745501396: Global MASTER-Net observations report
  24. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  25. EP EP240816b: Global MASTER-Net observations report
  26. EP240816b: TRT optical upper limit
  27. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  28. Fermi GRB 240814A: Global MASTER-Net observations report
  29. Fermi GRB 240814C: Global MASTER-Net observations report
  30. Fermi trigger No 745306088: Global MASTER-Net observations report
  31. GRB 240814C: Fermi GBM Final Real-time Localization
  32. Fermi GRB 240814B: Global MASTER-Net observations report
  33. GRB 240812B: SVOM/GRM observation
  34. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  35. GRB 240814B: Fermi GBM Final Real-time Localization
  36. GRB 240814A: Fermi GBM Final Real-time Localization
  37. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  38. Fermi trigger No 745220784: Global MASTER-Net observations report
  39. Konus-Wind detection of GRB 240811A
  40. Konus-Wind detection of GRB 240810A
  41. Fermi Gamma-ray Burst Monitor trigger 745220784/240813240 is not a GRB
  42. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  44. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  45. GRB 240809A: Correction to the VLA source position in GCN 37158
  46. GRB 240810A: SVOM/GRM observation
  47. Fermi Gamma-ray Burst Monitor trigger 240812940/745194848 is not a GRB
  48. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  49. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  50. GRB 240809A: ATA radio non-detection
  51. GRB 240812D: Fermi GBM Final Real-time Localization
  52. GRB 240812C: Fermi GBM Final Real-time Localization
  53. GRB 240809A : RAPAS follow-up observations
  54. GRB 240809A: VLA detection
  55. GRB 240809A: ALMA detection
  56. IPN triangulation of GRB 240810A (short)
  57. GRB 240811A: Swift-BAT refined analysis
  58. GRB 240809A: Swift-BAT refined analysis
  59. EP240807a: PRIME H-band upper limits
  60. GRB 240812B: AstroSat CZTI detection of a long burst
  61. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  62. GRB 240811A: Bassano Bresciano Observatory upper limit
  63. GRB 240811A: Swift-XRT refined Analysis
  64. Fermi Gamma-ray Burst Monitor trigger 745135620/240812255 is not a GRB
  65. GRB 240811A: Swift/UVOT Upper Limits
  66. EP240801a: Assy-Turgen optical observations
  67. Fermi GRB 240810A: Global MASTER-Net observations report
  68. Fermi Gamma-ray Burst Monitor trigger 240812094/745121685 is not a GRB
  69. GRB 240812A: Fermi GBM Final Real-time Localization
  70. GRB 240811A: LCOGT Optical Upper Limit
  71. GRB 240811A: Enhanced Swift-XRT position
  72. GRB 240811A: Upper limits with Mephisto
  73. Konus-Wind detection of GRB 240809A
  74. Fermi trigger No 745057312: Global MASTER-Net observations report
  75. Swift GRB 240811A: Global MASTER-Net observations report
  76. GRB 240811A: Swift detection of a burst
  77. Fermi Gamma-ray Burst Monitor trigger 745050426/240811269 is not a GRB
  78. GRB240809A: Liverpool Telescope optical follow-up observations
  79. GRB 240810A: Fermi GBM Final Real-time Localization
  80. GRB 240809A: REM detection of the optical afterglow
  81. GRB 240809A: Bassano Bresciano Observatory optical observations
  82. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  83. GRB 240809A: Conclusive redshift from VLT
  84. Fermi-LAT gamma-ray observations of IceCube-240808A
  85. GRB 240809A: KAIT optical observations
  86. GRB 240808A: AstroSat CZTI detection
  87. GRB 240809A: GIT afterglow observations
  88. GRB 240809B: MAXI/GSC detection
  89. GRB 240809A: Swift/UVOT Detection
  90. GRB 240809A: Tentative redshift from NOT
  91. GRB 240809A: Swift-XRT refined Analysis
  92. IPN triangulation of GRB 240807A / EP 240807a
  93. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  94. X-ray Transient EP240807a: PRIME near-infrared upper limits
  95. Swift GRB 240809A: Global MASTER-Net observations report
  96. GRB 240809A: JinShan optical observations
  97. GRB 240809A: Enhanced Swift-XRT position
  98. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  99. GRB 240809A: SVOM/GRM observation
  100. GRB 240808A: SVOM/GRM observation

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