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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

43084 results found.

  1. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  2. GRB 250507B: AstroSat CZTI detection
  3. EP250511a: Gemini optical counterpart observation
  4. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  5. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  6. EP250512a: Global MASTER-Net observations report
  7. EP250511a: FTW optical and NIR observations
  8. GRB 250512B/EP250512a: SVOM/VT optical fading
  9. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  10. EP250511a: Mephisto optical upper limits
  11. GRB 250507B: GRBAlpha detection
  12. GRB 250506A: GRBAlpha detection
  13. GRB 250512B: SVOM detection of a burst
  14. GRB 250507B: SVOM/GRM observation of a burst
  15. EP250512a: Einstein Probe detection of an X-ray transient
  16. GRB 250512A: Fermi GBM Final Real-time Localization
  17. EP250511a: REM optical/NIR observations
  18. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  19. EP250511a: SVOM/VT optical candidate comfirmation
  20. EP250511a: Global MASTER-Net observations report
  21. EP250511a: COLIBRÍ optical counterpart candidate
  22. EP250511a: BOOTES-5 optical upper limit
  23. EP250511a: Einstein Probe detection of an X-ray transient
  24. EP250508a: Gemini NIR upper limits
  25. GRB 250510B: Fermi GBM Observation
  26. Fermi GRB 250510C: Global MASTER-Net observations report
  27. Fermi GRB 250510B: Global MASTER-Net observations report
  28. GRB 250510C: Fermi GBM Final Real-time Localization
  29. GRB 250510A: Swift-XRT observations
  30. GRB 250509A: Fermi GBM Observation
  31. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  32. GRB 250510A: follow-up observation with EP-FXT
  33. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  34. GRB 250510B: Fermi GBM Final Localization
  35. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  36. GRB 250509A: Swift-XRT refined Analysis
  37. GRB 250510A: SVOM possible detection of a burst
  38. GRB 250507A: J-band observations with WINTER
  39. EP250508a: SVOM/VT optical candidate fading
  40. GRB 250509A: Enhanced Swift-XRT position
  41. GRB 250509A: Prompt enhanced Swift-XRT position
  42. Fermi GRB 250509A: Global MASTER-Net observations report
  43. Swift GRB 250509A: Global MASTER-Net observations report
  44. GRB 250509A: Swift detection of a burst
  45. GRB 250509A: Fermi GBM Final Real-time Localization
  46. GRB 250506A: NOT optical upper limits
  47. EP250508a: Liverpool Telescope optical upper limits
  48. EP250508a: follow-up observation with EP-FXT
  49. EP250508a: SVOM/VT optical candidate
  50. EP250508a: KAIT optical upper limit
  51. GRB 250507A: KAIT optical upper limit
  52. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  53. GRB 250505B: SVOM/GRM observation of a short burst
  54. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  55. GRB 250506A: GECAM detection
  56. EP250508a: REM optical/NIR observations
  57. GRB 250506A: Swift-XRT afterglow detection
  58. EP250508a: Global MASTER-Net observations report
  59. GRB 250506A: SVOM/VT optical upper limit
  60. EP250508a: COLIBRÍ Optical Limit
  61. EP250508a: Einstein Probe detection of an X-ray transient
  62. GRB 250507A: Swift-XRT refined Analysis
  63. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 250506A: Swift/UVOT Upper Limits
  65. GRB 250427B : SVOM detection of a burst through offline search
  66. GRB 250507A: follow-up observation with EP-FXT
  67. GRB 250430A / EP250430a: AstroSat CZTI detection
  68. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  69. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB 250507A: refined SVOM/MXT data analysis
  71. GRB 250507A: REM optical/NIR observations
  72. GRB 250507A: SVOM/VT optical upper limit
  73. GRB 250506A: Swift-XRT observations
  74. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  75. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  77. GRB 250507A: SVOM detection of a long burst
  78. GRB 250506A: Mephisto optical upper limits
  79. GRB 250504A: EIRSAT-1 GMOD Detection
  80. GRB 250506A: Swift ToO observations
  81. GRB 250502A: Bassano Bresciano Observatory upper limit
  82. IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
  83. IceCube Alert 250506.59: Global MASTER-Net observations report
  84. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  85. GRB 250506A: Xinglong 2.16m optical upper limit
  86. SVOM/sb25050601: EP-FXT observations
  87. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  88. GRB 250506A: REM optical/NIR upper limits
  89. GRB 250506A: Fermi GBM Observation
  90. GRB 250506A: Swift XRT observations and possible counterpart detection
  91. GRB 250506A: TRT optical observations
  92. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  93. GRB 250506A: SVOM detection of a burst
  94. GRB 250506A: Fermi GBM Final Real-time Localization
  95. GRB 250504A: Swift-XRT refined Analysis
  96. GRB 250504A: VLT/X-shooter upper limits
  97. Fermi GRB 250505A: Global MASTER-Net observations report
  98. GRB 250504A: SVOM/VT upper limit
  99. GRB 250504A: REM optical/NIR observations
  100. GRB 250502A: REM optical/NIR observations

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