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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 240809A: VLA detection
  2. GRB 240809A: ALMA detection
  3. IPN triangulation of GRB 240810A (short)
  4. GRB 240811A: Swift-BAT refined analysis
  5. GRB 240809A: Swift-BAT refined analysis
  6. EP240807a: PRIME H-band upper limits
  7. GRB 240812B: AstroSat CZTI detection of a long burst
  8. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  9. GRB 240811A: Bassano Bresciano Observatory upper limit
  10. GRB 240811A: Swift-XRT refined Analysis
  11. Fermi Gamma-ray Burst Monitor trigger 745135620/240812255 is not a GRB
  12. GRB 240811A: Swift/UVOT Upper Limits
  13. EP240801a: Assy-Turgen optical observations
  14. Fermi GRB 240810A: Global MASTER-Net observations report
  15. Fermi Gamma-ray Burst Monitor trigger 240812094/745121685 is not a GRB
  16. GRB 240812A: Fermi GBM Final Real-time Localization
  17. GRB 240811A: LCOGT Optical Upper Limit
  18. GRB 240811A: Enhanced Swift-XRT position
  19. GRB 240811A: Upper limits with Mephisto
  20. Konus-Wind detection of GRB 240809A
  21. Fermi trigger No 745057312: Global MASTER-Net observations report
  22. Swift GRB 240811A: Global MASTER-Net observations report
  23. GRB 240811A: Swift detection of a burst
  24. Fermi Gamma-ray Burst Monitor trigger 745050426/240811269 is not a GRB
  25. GRB240809A: Liverpool Telescope optical follow-up observations
  26. GRB 240810A: Fermi GBM Final Real-time Localization
  27. GRB 240809A: REM detection of the optical afterglow
  28. GRB 240809A: Bassano Bresciano Observatory optical observations
  29. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  30. GRB 240809A: Conclusive redshift from VLT
  31. Fermi-LAT gamma-ray observations of IceCube-240808A
  32. GRB 240809A: KAIT optical observations
  33. GRB 240808A: AstroSat CZTI detection
  34. GRB 240809A: GIT afterglow observations
  35. GRB 240809B: MAXI/GSC detection
  36. GRB 240809A: Swift/UVOT Detection
  37. GRB 240809A: Tentative redshift from NOT
  38. GRB 240809A: Swift-XRT refined Analysis
  39. IPN triangulation of GRB 240807A / EP 240807a
  40. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  41. X-ray Transient EP240807a: PRIME near-infrared upper limits
  42. Swift GRB 240809A: Global MASTER-Net observations report
  43. GRB 240809A: JinShan optical observations
  44. GRB 240809A: Enhanced Swift-XRT position
  45. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  46. GRB 240809A: SVOM/GRM observation
  47. GRB 240808A: SVOM/GRM observation
  48. GRB 240807A: SVOM/GRM observation
  49. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  50. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  51. EP240807a: STEP/T80S optical limits
  52. GRB 240807B: AstroSat CZTI detection of a short burst
  53. IceCube Alert 240808.27: Global MASTER-Net observations report
  54. EP EP240807a: Global MASTER-Net observations report
  55. EP EP240806a: Global MASTER-Net observations report
  56. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 240801A: GRBAlpha detection
  58. GRB 240807B: Fermi GBM Final Localization
  59. GRB 240710B: VZLUSAT-2 detection
  60. GRB 240805A: ATCA Radio Upper Limits
  61. Fermi trigger No 744761058: Global MASTER-Net observations report
  62. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  63. S240807h: Identification of a GW compact binary merger candidate
  64. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  65. EP240802a/GRB240802A: KAIT optical upper limit
  66. GRB 240720B: VZLUSAT-2 detection
  67. GRB 240710A: VZLUSAT-2 detection
  68. EP240806A: Liverpool Telescope optical follow-up observations
  69. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  70. GRB 240807A: Fermi GBM Final Localization
  71. EP240807a: EP-WXT detection of a fast X-ray transient
  72. EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
  73. GRB 240805B: GIT optical upper limit
  74. EP240806a: KAIT optical observations
  75. GRB 240805B: Swift-BAT refined analysis
  76. GRB 240805A: Swift-BAT refined analysis
  77. Fermi trigger No 744629911: Global MASTER-Net observations report
  78. EP240804a (GRB 240804B): NOT optical observations
  79. EP240806a: LCOGT optical counterpart detection
  80. Konus-Wind detection of GRB 240802A (EP240802a)
  81. Improved IPN triangulation of GRB 240802A / EP 240802a
  82. Konus-Wind detection of GRB 240805A
  83. GRB 240805B Bassano Bresciano Observatory upper limit
  84. GRB240805A: Fermi GBM Observation
  85. GRB 240805B: JinShan optical afterglow detection
  86. GRB 240804B/EP240804a: Correction to the GRB name in GCN 37071
  87. GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
  88. Konus-Wind detection of GRB 240804B (a counterpart of EP240804a)
  89. Fermi Gamma-ray Burst Monitor trigger 240806402/744629911 is not a GRB
  90. EP240806a: EP-FXT detection of the X-ray emission
  91. GRB 240626B: VZLUSAT-2 detection
  92. GRB 240624B: VZLUSAT-2 detection
  93. GRB 240619C: VZLUSAT-2 detection
  94. EP 240806A: LCO optical observations
  95. EP240806a: GSP optical counterpart detection
  96. EP240806a: EP-WXT detection of a fast X-ray transient
  97. GRB 240805B: Optical detection with 1.6m Mephisto
  98. EP240804a: BOOTES-6/DPRT optical detection
  99. GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
  100. GRB 240805B: Swift-XRT refined Analysis

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