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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"

36144 results found.

  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. GRB 240812B: AstroSat CZTI detection of a long burst
  7. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 240811A: Bassano Bresciano Observatory upper limit
  9. GRB 240811A: Swift-XRT refined Analysis
  10. Fermi Gamma-ray Burst Monitor trigger 745135620/240812255 is not a GRB
  11. GRB 240811A: Swift/UVOT Upper Limits
  12. EP240801a: Assy-Turgen optical observations
  13. Fermi GRB 240810A: Global MASTER-Net observations report
  14. Fermi Gamma-ray Burst Monitor trigger 240812094/745121685 is not a GRB
  15. GRB 240812A: Fermi GBM Final Real-time Localization
  16. GRB 240811A: LCOGT Optical Upper Limit
  17. GRB 240811A: Enhanced Swift-XRT position
  18. GRB 240811A: Upper limits with Mephisto
  19. Konus-Wind detection of GRB 240809A
  20. Swift GRB 240811A: Global MASTER-Net observations report
  21. GRB 240811A: Swift detection of a burst
  22. Fermi Gamma-ray Burst Monitor trigger 745050426/240811269 is not a GRB
  23. GRB 240810A: Fermi GBM Final Real-time Localization
  24. GRB 240809A: REM detection of the optical afterglow
  25. GRB 240809A: Bassano Bresciano Observatory optical observations
  26. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  27. GRB 240809A: Conclusive redshift from VLT
  28. GRB 240809A: KAIT optical observations
  29. GRB 240808A: AstroSat CZTI detection
  30. GRB 240809A: GIT afterglow observations
  31. GRB 240809B: MAXI/GSC detection
  32. GRB 240809A: Swift/UVOT Detection
  33. GRB 240809A: Tentative redshift from NOT
  34. GRB 240809A: Swift-XRT refined Analysis
  35. IPN triangulation of GRB 240807A / EP 240807a
  36. Swift GRB 240809A: Global MASTER-Net observations report
  37. GRB 240809A: JinShan optical observations
  38. GRB 240809A: Enhanced Swift-XRT position
  39. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  40. GRB 240809A: SVOM/GRM observation
  41. GRB 240808A: SVOM/GRM observation
  42. GRB 240807A: SVOM/GRM observation
  43. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  44. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  45. EP240807a: STEP/T80S optical limits
  46. GRB 240807B: AstroSat CZTI detection of a short burst
  47. GRB 240801A: GRBAlpha detection
  48. GRB 240807B: Fermi GBM Final Localization
  49. GRB 240710B: VZLUSAT-2 detection
  50. GRB 240805A: ATCA Radio Upper Limits
  51. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  52. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  53. EP240802a/GRB240802A: KAIT optical upper limit
  54. GRB 240720B: VZLUSAT-2 detection
  55. GRB 240710A: VZLUSAT-2 detection
  56. GRB 240807A: Fermi GBM Final Localization
  57. GRB 240805B: GIT optical upper limit
  58. EP240806a: KAIT optical observations
  59. GRB 240805B: Swift-BAT refined analysis
  60. GRB 240805A: Swift-BAT refined analysis
  61. EP240804a (GRB 240804B): NOT optical observations
  62. Konus-Wind detection of GRB 240802A (EP240802a)
  63. Improved IPN triangulation of GRB 240802A / EP 240802a
  64. Konus-Wind detection of GRB 240805A
  65. GRB 240805B Bassano Bresciano Observatory upper limit
  66. GRB240805A: Fermi GBM Observation
  67. GRB 240805B: JinShan optical afterglow detection
  68. GRB 240804B/EP240804a: Correction to the GRB name in GCN 37071
  69. GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
  70. Konus-Wind detection of GRB 240804B (a counterpart of EP240804a)
  71. Fermi Gamma-ray Burst Monitor trigger 240806402/744629911 is not a GRB
  72. GRB 240626B: VZLUSAT-2 detection
  73. GRB 240624B: VZLUSAT-2 detection
  74. GRB 240619C: VZLUSAT-2 detection
  75. EP 240806A: LCO optical observations
  76. GRB 240805B: Optical detection with 1.6m Mephisto
  77. GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
  78. GRB 240805B: Swift-XRT refined Analysis
  79. GRB 240805B: Swift/UVOT Upper Limits
  80. GRB 240805A: Swift/UVOT Upper Limits
  81. GRB 240805B: BTA optical afterglow candidate
  82. GRB 240805A: SVOM/GRM observation
  83. GRB 240805B: Enhanced Swift-XRT position
  84. GRB 240805B: LCOGT Optical Upper Limits
  85. Swift GRB 240805B: Global MASTER-Net observations report
  86. GRB 240805B: JinShan optical upper limits
  87. Fermi GRB 240805A: Global MASTER-Net observations report
  88. Swift GRB 240805A: Global MASTER-Net observations report
  89. Fermi Gamma-ray Burst Monitor trigger 744558410/240805574 is not a GRB
  90. GRB 240805A: Swift-XRT refined Analysis
  91. GRB 240805B: Swift detection of a burst
  92. GRB 240805A: Fermi-LAT detection
  93. GRB 240805A: INTEGRAL spectral analysis
  94. EP240801a: Continued optical observations at ZTSh (CraO)
  95. GRB 240805A: A long GRB detected by INTEGRAL
  96. GRB 240805A: Swift detection of a burst
  97. GRB 240805A: Fermi GBM Final Real-time Localization
  98. Fermi GRB 240804A: Global MASTER-Net observations report
  99. EP240802a: Montarrenti Observatory optical upper limit
  100. GRB 240804A: Fermi GBM Final Real-time Localization

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