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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. Fermi GRB 240814A: Global MASTER-Net observations report
  2. Fermi GRB 240814C: Global MASTER-Net observations report
  3. Fermi trigger No 745306088: Global MASTER-Net observations report
  4. GRB 240814C: Fermi GBM Final Real-time Localization
  5. Fermi GRB 240814B: Global MASTER-Net observations report
  6. GRB 240812B: SVOM/GRM observation
  7. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  8. GRB 240814B: Fermi GBM Final Real-time Localization
  9. GRB 240814A: Fermi GBM Final Real-time Localization
  10. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  11. Fermi trigger No 745220784: Global MASTER-Net observations report
  12. Konus-Wind detection of GRB 240811A
  13. Konus-Wind detection of GRB 240810A
  14. Fermi Gamma-ray Burst Monitor trigger 745220784/240813240 is not a GRB
  15. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  17. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  18. GRB 240809A: Correction to the VLA source position in GCN 37158
  19. GRB 240810A: SVOM/GRM observation
  20. Fermi Gamma-ray Burst Monitor trigger 240812940/745194848 is not a GRB
  21. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  22. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  23. GRB 240809A: ATA radio non-detection
  24. GRB 240812D: Fermi GBM Final Real-time Localization
  25. GRB 240812C: Fermi GBM Final Real-time Localization
  26. GRB 240809A : RAPAS follow-up observations
  27. GRB 240809A: VLA detection
  28. GRB 240809A: ALMA detection
  29. IPN triangulation of GRB 240810A (short)
  30. GRB 240811A: Swift-BAT refined analysis
  31. GRB 240809A: Swift-BAT refined analysis
  32. EP240807a: PRIME H-band upper limits
  33. GRB 240812B: AstroSat CZTI detection of a long burst
  34. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  35. GRB 240811A: Bassano Bresciano Observatory upper limit
  36. GRB 240811A: Swift-XRT refined Analysis
  37. Fermi Gamma-ray Burst Monitor trigger 745135620/240812255 is not a GRB
  38. GRB 240811A: Swift/UVOT Upper Limits
  39. EP240801a: Assy-Turgen optical observations
  40. Fermi GRB 240810A: Global MASTER-Net observations report
  41. Fermi Gamma-ray Burst Monitor trigger 240812094/745121685 is not a GRB
  42. GRB 240812A: Fermi GBM Final Real-time Localization
  43. GRB 240811A: LCOGT Optical Upper Limit
  44. GRB 240811A: Enhanced Swift-XRT position
  45. GRB 240811A: Upper limits with Mephisto
  46. Konus-Wind detection of GRB 240809A
  47. Fermi trigger No 745057312: Global MASTER-Net observations report
  48. Swift GRB 240811A: Global MASTER-Net observations report
  49. GRB 240811A: Swift detection of a burst
  50. Fermi Gamma-ray Burst Monitor trigger 745050426/240811269 is not a GRB
  51. GRB240809A: Liverpool Telescope optical follow-up observations
  52. GRB 240810A: Fermi GBM Final Real-time Localization
  53. GRB 240809A: REM detection of the optical afterglow
  54. GRB 240809A: Bassano Bresciano Observatory optical observations
  55. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  56. GRB 240809A: Conclusive redshift from VLT
  57. Fermi-LAT gamma-ray observations of IceCube-240808A
  58. GRB 240809A: KAIT optical observations
  59. GRB 240808A: AstroSat CZTI detection
  60. GRB 240809A: GIT afterglow observations
  61. GRB 240809B: MAXI/GSC detection
  62. GRB 240809A: Swift/UVOT Detection
  63. GRB 240809A: Tentative redshift from NOT
  64. GRB 240809A: Swift-XRT refined Analysis
  65. IPN triangulation of GRB 240807A / EP 240807a
  66. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  67. X-ray Transient EP240807a: PRIME near-infrared upper limits
  68. Swift GRB 240809A: Global MASTER-Net observations report
  69. GRB 240809A: JinShan optical observations
  70. GRB 240809A: Enhanced Swift-XRT position
  71. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  72. GRB 240809A: SVOM/GRM observation
  73. GRB 240808A: SVOM/GRM observation
  74. GRB 240807A: SVOM/GRM observation
  75. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  76. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  77. EP240807a: STEP/T80S optical limits
  78. GRB 240807B: AstroSat CZTI detection of a short burst
  79. IceCube Alert 240808.27: Global MASTER-Net observations report
  80. EP EP240807a: Global MASTER-Net observations report
  81. EP EP240806a: Global MASTER-Net observations report
  82. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  83. GRB 240801A: GRBAlpha detection
  84. GRB 240807B: Fermi GBM Final Localization
  85. GRB 240710B: VZLUSAT-2 detection
  86. GRB 240805A: ATCA Radio Upper Limits
  87. Fermi trigger No 744761058: Global MASTER-Net observations report
  88. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  89. S240807h: Identification of a GW compact binary merger candidate
  90. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  91. EP240802a/GRB240802A: KAIT optical upper limit
  92. GRB 240720B: VZLUSAT-2 detection
  93. GRB 240710A: VZLUSAT-2 detection
  94. EP240806A: Liverpool Telescope optical follow-up observations
  95. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  96. GRB 240807A: Fermi GBM Final Localization
  97. EP240807a: EP-WXT detection of a fast X-ray transient
  98. EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
  99. GRB 240805B: GIT optical upper limit
  100. EP240806a: KAIT optical observations

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