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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"

28261 results found.

  1. GRB 250512B: SVOM detection of a burst
  2. EP250512a: Einstein Probe detection of an X-ray transient
  3. EP250511a: REM optical/NIR observations
  4. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  5. EP250511a: COLIBRÍ optical counterpart candidate
  6. EP250511a: BOOTES-5 optical upper limit
  7. EP250511a: Einstein Probe detection of an X-ray transient
  8. EP250508a: Gemini NIR upper limits
  9. GRB 250510B: Fermi GBM Observation
  10. GRB 250510A: Swift-XRT observations
  11. GRB 250509A: Fermi GBM Observation
  12. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  13. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  14. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  15. GRB 250509A: Swift-XRT refined Analysis
  16. GRB 250510A: SVOM possible detection of a burst
  17. GRB 250507A: J-band observations with WINTER
  18. GRB 250509A: Enhanced Swift-XRT position
  19. GRB 250509A: Swift detection of a burst
  20. GRB 250506A: NOT optical upper limits
  21. EP250508a: Liverpool Telescope optical upper limits
  22. EP250508a: KAIT optical upper limit
  23. GRB 250507A: KAIT optical upper limit
  24. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  25. GRB 250505B: SVOM/GRM observation of a short burst
  26. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  27. EP250508a: REM optical/NIR observations
  28. GRB 250506A: Swift-XRT afterglow detection
  29. EP250508a: COLIBRÍ Optical Limit
  30. EP250508a: Einstein Probe detection of an X-ray transient
  31. GRB 250507A: Swift-XRT refined Analysis
  32. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 250506A: Swift/UVOT Upper Limits
  34. GRB 250507A: follow-up observation with EP-FXT
  35. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  36. GRB 250507A: REM optical/NIR observations
  37. GRB 250507A: SVOM/VT optical upper limit
  38. GRB 250506A: Swift-XRT observations
  39. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  40. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  41. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  42. GRB 250507A: SVOM detection of a long burst
  43. GRB 250506A: Mephisto optical upper limits
  44. GRB 250504A: EIRSAT-1 GMOD Detection
  45. GRB 250502A: Bassano Bresciano Observatory upper limit
  46. GRB 250506A: Xinglong 2.16m optical upper limit
  47. SVOM/sb25050601: EP-FXT observations
  48. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  49. GRB 250506A: REM optical/NIR upper limits
  50. GRB 250506A: Fermi GBM Observation
  51. GRB 250506A: Swift XRT observations and possible counterpart detection
  52. GRB 250506A: TRT optical observations
  53. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  54. GRB 250506A: SVOM detection of a burst
  55. GRB 250504A: Swift-BAT refined analysis
  56. GRB 250430A: Swift-BAT refined analysis
  57. GRB 250504A: Swift-XRT refined Analysis
  58. GRB 250504A: VLT/X-shooter upper limits
  59. GRB 250504A: REM optical/NIR observations
  60. GRB 250502A: REM optical/NIR observations
  61. GRB 250504A: MeerLICHT optical afterglow detection
  62. GRB 250504A: Fermi GBM Observation
  63. GRB 250504A: Enhanced Swift-XRT position
  64. Fermi GRB 250504A: Global MASTER-Net observations report
  65. GRB 250504A: Swift detection of a burst
  66. GRB 250502A: Swift/UVOT Follow up
  67. GRB 250502A: Mondy and Tien-Shan Optical Observations
  68. GRB 250502A: KAIT optical observations
  69. GRB 250502A: Montarrenti Observatory optical detection
  70. GRB 250502A: Swift-XRT afterglow detection
  71. GRB 250502A: NOT optical observations
  72. GRB 250502B: AstroSat CZTI detection
  73. GRB 250502A: AKO Optical Afterglow Detection
  74. GRB 250502A: LCO optical counterpart detection
  75. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  76. GRB 250407A: VZLUSAT-2 detection
  77. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  78. GRB 250502B: DDOTI Optical Observations
  79. GRB 250430A: Swift-XRT refined Analysis
  80. GRB 250502A: Early optical counterpart detection by LCO.
  81. GRB 250430A: Swift/UVOT Detection
  82. GRB 250502A: TRT optical afterglow confirmation
  83. GRB 250430A: Enhanced Swift-XRT position
  84. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  85. GRB 250502A: SVOM detection of a burst
  86. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  87. GRB 250430A: KAIT optical observations
  88. GRB 250430A / EP250430a: J-band upper limits with WINTER
  89. GRB 250430A: NUTTelA-TAO Early Measurements
  90. GRB 250430A: DDOTI Optical Observations
  91. GRB 250430A: Leavitt Observatory optical upper limit
  92. GRB 250430A: Bassano Bresciano Observatory upper limit
  93. GRB 250430A : MITSuME Akeno optical upper limits
  94. SVOM/sb25043004: EP-FXT observations
  95. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  96. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  97. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  98. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 250430A: AKO Optical Afterglow Detection
  100. GRB 250430A: Kanata optical upper limit

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