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

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