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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"

28291 results found.

  1. GRB 250520A: Swift-XRT refined Analysis
  2. GRB 250520A: REM optical/NIR early observations
  3. GRB 250520A：SVOM/VT optical candidate
  4. GRB 250520A: COLIBRÍ optical upper limit
  5. GRB 250520A: DDOTI Optical Upper Limit
  6. GRB 250520A: AstroSat CZTI detection of a short burst
  7. GRB 250520A: Enhanced Swift-XRT position
  8. GRB 250520A: Swift detection of a burst
  9. GRB 250516A: Swift-BAT refined analysis
  10. GRB 250516A: COLIBRÍ optical upper limit
  11. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  12. GRB 250515A: Swift-XRT observations
  13. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  14. GRB 250515A: 1.6m Mephisto optical detection
  15. GRB 250516A: Fermi GBM Observation
  16. GRB 250516A: Swift-XRT refined Analysis
  17. GRB 250516A: Swift/UVOT Detection
  18. GRB 250516B: GECAM-B detection of a bright long burst
  19. GRB 250516A: Enhanced Swift-XRT position
  20. GRB 250516A: Swift detection of a burst
  21. MAXI GRB250515.65: Global MASTER-Net observations report
  22. GRB 250424A: COLIBRÍ detection of the associated supernova
  23. GRB 250502A: TESS observations
  24. GRB 250509A: Swift-BAT refined analysis
  25. Fermi GRB 250512A: Global MASTER-Net observations report
  26. EP250512a/GRB 250512B: REM optical/NIR observations
  27. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  28. GRB 250507B: AstroSat CZTI detection
  29. EP250511a: Gemini optical counterpart observation
  30. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  31. EP250511a: Mephisto optical upper limits
  32. GRB 250512B: SVOM detection of a burst
  33. EP250512a: Einstein Probe detection of an X-ray transient
  34. EP250511a: REM optical/NIR observations
  35. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  36. EP250511a: COLIBRÍ optical counterpart candidate
  37. EP250511a: BOOTES-5 optical upper limit
  38. EP250511a: Einstein Probe detection of an X-ray transient
  39. EP250508a: Gemini NIR upper limits
  40. GRB 250510B: Fermi GBM Observation
  41. GRB 250510A: Swift-XRT observations
  42. GRB 250509A: Fermi GBM Observation
  43. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  44. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  45. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  46. GRB 250509A: Swift-XRT refined Analysis
  47. GRB 250510A: SVOM possible detection of a burst
  48. GRB 250507A: J-band observations with WINTER
  49. GRB 250509A: Enhanced Swift-XRT position
  50. GRB 250509A: Swift detection of a burst
  51. GRB 250506A: NOT optical upper limits
  52. EP250508a: Liverpool Telescope optical upper limits
  53. EP250508a: KAIT optical upper limit
  54. GRB 250507A: KAIT optical upper limit
  55. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  56. GRB 250505B: SVOM/GRM observation of a short burst
  57. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  58. EP250508a: REM optical/NIR observations
  59. GRB 250506A: Swift-XRT afterglow detection
  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 250507A: follow-up observation with EP-FXT
  66. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. GRB 250507A: REM optical/NIR observations
  68. GRB 250507A: SVOM/VT optical upper limit
  69. GRB 250506A: Swift-XRT observations
  70. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  71. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  72. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  73. GRB 250507A: SVOM detection of a long burst
  74. GRB 250506A: Mephisto optical upper limits
  75. GRB 250504A: EIRSAT-1 GMOD Detection
  76. GRB 250502A: Bassano Bresciano Observatory upper limit
  77. GRB 250506A: Xinglong 2.16m optical upper limit
  78. SVOM/sb25050601: EP-FXT observations
  79. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  80. GRB 250506A: REM optical/NIR upper limits
  81. GRB 250506A: Fermi GBM Observation
  82. GRB 250506A: Swift XRT observations and possible counterpart detection
  83. GRB 250506A: TRT optical observations
  84. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  85. GRB 250506A: SVOM detection of a burst
  86. GRB 250504A: Swift-BAT refined analysis
  87. GRB 250430A: Swift-BAT refined analysis
  88. GRB 250504A: Swift-XRT refined Analysis
  89. GRB 250504A: VLT/X-shooter upper limits
  90. GRB 250504A: REM optical/NIR observations
  91. GRB 250502A: REM optical/NIR observations
  92. GRB 250504A: MeerLICHT optical afterglow detection
  93. GRB 250504A: Fermi GBM Observation
  94. GRB 250504A: Enhanced Swift-XRT position
  95. Fermi GRB 250504A: Global MASTER-Net observations report
  96. GRB 250504A: Swift detection of a burst
  97. GRB 250502A: Swift/UVOT Follow up
  98. GRB 250502A: Mondy and Tien-Shan Optical Observations
  99. GRB 250502A: KAIT optical observations
  100. GRB 250502A: Montarrenti Observatory optical detection

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