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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"

20545 results found.

  1. GRB 250521D: LAST tentative optical counterpart candidate
  2. GRB 250520A: 10 GHz VLA radio source
  3. GRB 250521A: DDOTI Optical Upper Limit
  4. GRB 250520A: VLT/FORS2 Optical Observation
  5. GRB 250502A: Tautenburg observations
  6. GRB 250520A: Swift/UVOT Upper Limits
  7. Konus-Wind detection of GRB 250516B
  8. IPN triangulation of GRB 250516B
  9. GRB 250520A: J-band observations with WINTER
  10. GRB 250520A: Gemini-South optical observations
  11. GRB 250520A: REM optical/NIR early observations
  12. GRB 250520A：SVOM/VT optical candidate
  13. GRB 250520A: COLIBRÍ optical upper limit
  14. GRB 250520A: DDOTI Optical Upper Limit
  15. GRB 250520A: Enhanced Swift-XRT position
  16. GRB 250520A: Swift detection of a burst
  17. GRB 250516A: COLIBRÍ optical upper limit
  18. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  19. GRB 250515A: Swift-XRT observations
  20. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  21. GRB 250515A: 1.6m Mephisto optical detection
  22. GRB 250516A: Swift/UVOT Detection
  23. GRB 250516A: Enhanced Swift-XRT position
  24. GRB 250516A: Swift detection of a burst
  25. GRB 250424A: COLIBRÍ detection of the associated supernova
  26. GRB 250502A: TESS observations
  27. EP250512a/GRB 250512B: REM optical/NIR observations
  28. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  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: Einstein Probe detection of an X-ray transient
  38. EP250508a: Gemini NIR upper limits
  39. GRB 250510A: Swift-XRT observations
  40. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  41. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  42. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  43. GRB 250507A: J-band observations with WINTER
  44. GRB 250509A: Enhanced Swift-XRT position
  45. GRB 250509A: Swift detection of a burst
  46. GRB 250506A: NOT optical upper limits
  47. EP250508a: Liverpool Telescope optical upper limits
  48. EP250508a: KAIT optical upper limit
  49. GRB 250507A: KAIT optical upper limit
  50. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  51. GRB 250505B: SVOM/GRM observation of a short burst
  52. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  53. EP250508a: REM optical/NIR observations
  54. GRB 250506A: Swift-XRT afterglow detection
  55. EP250508a: COLIBRÍ Optical Limit
  56. EP250508a: Einstein Probe detection of an X-ray transient
  57. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 250506A: Swift/UVOT Upper Limits
  59. GRB 250427B : SVOM detection of a burst through offline search
  60. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. GRB 250507A: REM optical/NIR observations
  62. GRB 250507A: SVOM/VT optical upper limit
  63. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  64. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  65. GRB 250507A: SVOM detection of a long burst
  66. GRB 250506A: Mephisto optical upper limits
  67. GRB 250502A: Bassano Bresciano Observatory upper limit
  68. GRB 250506A: Xinglong 2.16m optical upper limit
  69. GRB 250506A: REM optical/NIR upper limits
  70. GRB 250506A: TRT optical observations
  71. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  72. GRB 250504A: VLT/X-shooter upper limits
  73. GRB 250504A: REM optical/NIR observations
  74. GRB 250502A: REM optical/NIR observations
  75. GRB 250504A: MeerLICHT optical afterglow detection
  76. GRB 250504A: Enhanced Swift-XRT position
  77. GRB 250504A: Swift detection of a burst
  78. GRB 250504A: Fermi GBM Final Real-time Localization
  79. GRB 250502A: Swift/UVOT Follow up
  80. GRB 250502A: KAIT optical observations
  81. GRB 250502A: Montarrenti Observatory optical detection
  82. GRB 250502A: Swift-XRT afterglow detection
  83. GRB 250502A: NOT optical observations
  84. GRB 250502B: AstroSat CZTI detection
  85. GRB 250502A: AKO Optical Afterglow Detection
  86. GRB 250502A: LCO optical counterpart detection
  87. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  88. GRB 250502B: DDOTI Optical Observations
  89. GRB 250502A: Early optical counterpart detection by LCO.
  90. GRB 250430A: Swift/UVOT Detection
  91. GRB 250502A: TRT optical afterglow confirmation
  92. GRB 250430A: Enhanced Swift-XRT position
  93. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  94. GRB 250502A: SVOM detection of a burst
  95. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  96. GRB 250430A: KAIT optical observations
  97. GRB 250430A / EP250430a: J-band upper limits with WINTER
  98. GRB 250430A: NUTTelA-TAO Early Measurements
  99. GRB 250430A: DDOTI Optical Observations
  100. GRB 250430A: Leavitt Observatory optical upper limit

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