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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 240819A: JinShan optical upper limits on one Swift/XRT source
  2. GRB 240820B: SVOM/GRM observation
  3. EP240820a: TRT optical upper limit
  4. EP240820a: EP detection of a fast X-ray transient
  5. GRB 240819A: KAIT optical upper limit
  6. EP240816a: PRIME upper limits
  7. Trigger 1249653: Swift detection of SGR 1E 1841-045 / Kes 73
  8. Fermi trigger No 745873283: Global MASTER-Net observations report
  9. Fermi trigger No 745871958: Global MASTER-Net observations report
  10. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  11. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  12. GRB 240819A: X-ray follow-up observation with EP-FXT
  13. Fermi Gamma-ray Burst Monitor trigger 745811685 / 240820080 is not a GRB
  14. GRB 240820A: Fermi GBM Final Real-time Localization
  15. GRB 240819A: Swift ToO observations
  16. GRB 240814A: SVOM/GRM observation
  17. EP240816b: Liverpool Telescope optical follow-up observations
  18. GRB 240814C: SVOM/GRM observation
  19. EP240816a: BOOTES-6/DPRT optical upper limit
  20. GRB 240815A: SVOM/GRM observation
  21. GRB 240817A: Fermi GBM Final Real-time Localization
  22. Integral GRB240816.79: Global MASTER-Net observations report
  23. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  24. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  25. IBAS Alert n.10856: not a GRB
  26. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  27. EP240816b: KAIT optical upper limit
  28. GRB 240814B: GRBAlpha detection
  29. Fermi trigger No 745501396: Global MASTER-Net observations report
  30. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  31. EP EP240816b: Global MASTER-Net observations report
  32. EP240816b: TRT optical upper limit
  33. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  34. Fermi GRB 240814A: Global MASTER-Net observations report
  35. Fermi GRB 240814C: Global MASTER-Net observations report
  36. Fermi trigger No 745306088: Global MASTER-Net observations report
  37. GRB 240814C: Fermi GBM Final Real-time Localization
  38. Fermi GRB 240814B: Global MASTER-Net observations report
  39. GRB 240812B: SVOM/GRM observation
  40. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  41. GRB 240814B: Fermi GBM Final Real-time Localization
  42. GRB 240814A: Fermi GBM Final Real-time Localization
  43. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  44. Fermi trigger No 745220784: Global MASTER-Net observations report
  45. Konus-Wind detection of GRB 240811A
  46. Konus-Wind detection of GRB 240810A
  47. Fermi Gamma-ray Burst Monitor trigger 745220784/240813240 is not a GRB
  48. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  50. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  51. GRB 240809A: Correction to the VLA source position in GCN 37158
  52. GRB 240810A: SVOM/GRM observation
  53. Fermi Gamma-ray Burst Monitor trigger 240812940/745194848 is not a GRB
  54. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  55. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  56. GRB 240809A: ATA radio non-detection
  57. GRB 240812D: Fermi GBM Final Real-time Localization
  58. GRB 240812C: Fermi GBM Final Real-time Localization
  59. GRB 240809A : RAPAS follow-up observations
  60. GRB 240809A: VLA detection
  61. GRB 240809A: ALMA detection
  62. IPN triangulation of GRB 240810A (short)
  63. GRB 240811A: Swift-BAT refined analysis
  64. GRB 240809A: Swift-BAT refined analysis
  65. EP240807a: PRIME H-band upper limits
  66. GRB 240812B: AstroSat CZTI detection of a long burst
  67. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  68. GRB 240811A: Bassano Bresciano Observatory upper limit
  69. GRB 240811A: Swift-XRT refined Analysis
  70. Fermi Gamma-ray Burst Monitor trigger 745135620/240812255 is not a GRB
  71. GRB 240811A: Swift/UVOT Upper Limits
  72. EP240801a: Assy-Turgen optical observations
  73. Fermi GRB 240810A: Global MASTER-Net observations report
  74. Fermi Gamma-ray Burst Monitor trigger 240812094/745121685 is not a GRB
  75. GRB 240812A: Fermi GBM Final Real-time Localization
  76. GRB 240811A: LCOGT Optical Upper Limit
  77. GRB 240811A: Enhanced Swift-XRT position
  78. GRB 240811A: Upper limits with Mephisto
  79. Konus-Wind detection of GRB 240809A
  80. Fermi trigger No 745057312: Global MASTER-Net observations report
  81. Swift GRB 240811A: Global MASTER-Net observations report
  82. GRB 240811A: Swift detection of a burst
  83. Fermi Gamma-ray Burst Monitor trigger 745050426/240811269 is not a GRB
  84. GRB240809A: Liverpool Telescope optical follow-up observations
  85. GRB 240810A: Fermi GBM Final Real-time Localization
  86. GRB 240809A: REM detection of the optical afterglow
  87. GRB 240809A: Bassano Bresciano Observatory optical observations
  88. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  89. GRB 240809A: Conclusive redshift from VLT
  90. Fermi-LAT gamma-ray observations of IceCube-240808A
  91. GRB 240809A: KAIT optical observations
  92. GRB 240808A: AstroSat CZTI detection
  93. GRB 240809A: GIT afterglow observations
  94. GRB 240809B: MAXI/GSC detection
  95. GRB 240809A: Swift/UVOT Detection
  96. GRB 240809A: Tentative redshift from NOT
  97. GRB 240809A: Swift-XRT refined Analysis
  98. IPN triangulation of GRB 240807A / EP 240807a
  99. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  100. X-ray Transient EP240807a: PRIME near-infrared upper limits

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