Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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"

23442 results found.

  1. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  2. GRB 250515A: 1.6m Mephisto optical detection
  3. GRB 250516A: Swift-XRT refined Analysis
  4. GRB 250516A: Swift/UVOT Detection
  5. GRB 250516A: Enhanced Swift-XRT position
  6. GRB 250516A: Swift detection of a burst
  7. GRB 250512B / EP250512a: SVOM/GRM analysis
  8. GRB 250515A: GOTO candidate optical counterpart
  9. GRB 250424A: COLIBRÍ detection of the associated supernova
  10. GRB 250502A: TESS observations
  11. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  12. EP250512a/GRB 250512B: REM optical/NIR observations
  13. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  14. EP250511a: Gemini optical counterpart observation
  15. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  16. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  17. EP250511a: FTW optical and NIR observations
  18. EP250511a: Mephisto optical upper limits
  19. GRB 250512B: SVOM detection of a burst
  20. EP250512a: Einstein Probe detection of an X-ray transient
  21. EP250511a: REM optical/NIR observations
  22. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  23. EP250511a: COLIBRÍ optical counterpart candidate
  24. EP250511a: Einstein Probe detection of an X-ray transient
  25. EP250508a: Gemini NIR upper limits
  26. GRB 250510A: Swift-XRT observations
  27. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  28. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  29. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  30. GRB 250509A: Swift-XRT refined Analysis
  31. GRB 250507A: J-band observations with WINTER
  32. GRB 250509A: Enhanced Swift-XRT position
  33. GRB 250509A: Swift detection of a burst
  34. GRB 250506A: NOT optical upper limits
  35. EP250508a: Liverpool Telescope optical upper limits
  36. EP250508a: KAIT optical upper limit
  37. GRB 250507A: KAIT optical upper limit
  38. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  39. GRB 250505B: SVOM/GRM observation of a short burst
  40. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  41. EP250508a: REM optical/NIR observations
  42. GRB 250506A: Swift-XRT afterglow detection
  43. GRB 250506A: SVOM/VT optical upper limit
  44. EP250508a: COLIBRÍ Optical Limit
  45. EP250508a: Einstein Probe detection of an X-ray transient
  46. GRB 250506A: Swift/UVOT Upper Limits
  47. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  48. GRB 250507A: REM optical/NIR observations
  49. GRB 250507A: SVOM/VT optical upper limit
  50. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  51. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  52. GRB 250507A: SVOM detection of a long burst
  53. GRB 250506A: Mephisto optical upper limits
  54. GRB 250502A: Bassano Bresciano Observatory upper limit
  55. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  56. GRB 250506A: Xinglong 2.16m optical upper limit
  57. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  58. GRB 250506A: REM optical/NIR upper limits
  59. GRB 250506A: Swift XRT observations and possible counterpart detection
  60. GRB 250506A: TRT optical observations
  61. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  62. GRB 250506A: SVOM detection of a burst
  63. GRB 250504A: Swift-XRT refined Analysis
  64. GRB 250504A: VLT/X-shooter upper limits
  65. Fermi GRB 250505A: Global MASTER-Net observations report
  66. GRB 250504A: SVOM/VT upper limit
  67. GRB 250504A: REM optical/NIR observations
  68. GRB 250502A: REM optical/NIR observations
  69. GRB 250504A: MeerLICHT optical afterglow detection
  70. GRB 250504A: Enhanced Swift-XRT position
  71. GRB 250504A: Swift detection of a burst
  72. GRB 250502A: Swift/UVOT Follow up
  73. GRB 250502A: KAIT optical observations
  74. GRB 250502A: Montarrenti Observatory optical detection
  75. GRB 250502A: Swift-XRT afterglow detection
  76. GRB 250502A: NOT optical observations
  77. GRB 250502B: AstroSat CZTI detection
  78. GRB 250502A: AKO Optical Afterglow Detection
  79. GRB 250502A: LCO optical counterpart detection
  80. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  81. GRB 250502B: DDOTI Optical Observations
  82. GRB 250502A: Early optical counterpart detection by LCO.
  83. GRB 250430A: Swift/UVOT Detection
  84. GRB 250502A: TRT optical afterglow confirmation
  85. GRB 250430A: Enhanced Swift-XRT position
  86. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  87. GRB 250502A: SVOM detection of a burst
  88. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  89. GRB 250430A: KAIT optical observations
  90. GRB 250430A / EP250430a: J-band upper limits with WINTER
  91. GRB 250430A: DDOTI Optical Observations
  92. GRB 250430A: Leavitt Observatory optical upper limit
  93. GRB 250430A: Bassano Bresciano Observatory upper limit
  94. GRB 250430A : MITSuME Akeno optical upper limits
  95. SVOM/sb25043004: EP-FXT observations
  96. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  97. GRB 250430A: AKO Optical Afterglow Detection
  98. GRB 250430A: Kanata optical upper limit
  99. EP 250427A: Optical counterpart detection by LCO.
  100. GRB 250430A: Swift detection of a burst with optical counterpart

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov