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"

23409 results found.

  1. GRB 250506A: NOT optical upper limits
  2. EP250508a: Liverpool Telescope optical upper limits
  3. EP250508a: KAIT optical upper limit
  4. GRB 250507A: KAIT optical upper limit
  5. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  6. GRB 250505B: SVOM/GRM observation of a short burst
  7. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  8. EP250508a: REM optical/NIR observations
  9. GRB 250506A: Swift-XRT afterglow detection
  10. GRB 250506A: SVOM/VT optical upper limit
  11. EP250508a: COLIBRÍ Optical Limit
  12. EP250508a: Einstein Probe detection of an X-ray transient
  13. GRB 250506A: Swift/UVOT Upper Limits
  14. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  15. GRB 250507A: REM optical/NIR observations
  16. GRB 250507A: SVOM/VT optical upper limit
  17. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  18. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  19. GRB 250507A: SVOM detection of a long burst
  20. GRB 250506A: Mephisto optical upper limits
  21. GRB 250502A: Bassano Bresciano Observatory upper limit
  22. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  23. GRB 250506A: Xinglong 2.16m optical upper limit
  24. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  25. GRB 250506A: REM optical/NIR upper limits
  26. GRB 250506A: Swift XRT observations and possible counterpart detection
  27. GRB 250506A: TRT optical observations
  28. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  29. GRB 250506A: SVOM detection of a burst
  30. GRB 250504A: Swift-XRT refined Analysis
  31. GRB 250504A: VLT/X-shooter upper limits
  32. Fermi GRB 250505A: Global MASTER-Net observations report
  33. GRB 250504A: SVOM/VT upper limit
  34. GRB 250504A: REM optical/NIR observations
  35. GRB 250502A: REM optical/NIR observations
  36. GRB 250504A: MeerLICHT optical afterglow detection
  37. GRB 250504A: Enhanced Swift-XRT position
  38. GRB 250504A: Swift detection of a burst
  39. GRB 250502A: Swift/UVOT Follow up
  40. GRB 250502A: KAIT optical observations
  41. GRB 250502A: Montarrenti Observatory optical detection
  42. GRB 250502A: Swift-XRT afterglow detection
  43. GRB 250502A: NOT optical observations
  44. GRB 250502B: AstroSat CZTI detection
  45. GRB 250502A: AKO Optical Afterglow Detection
  46. GRB 250502A: LCO optical counterpart detection
  47. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  48. GRB 250502B: DDOTI Optical Observations
  49. GRB 250502A: Early optical counterpart detection by LCO.
  50. GRB 250430A: Swift/UVOT Detection
  51. GRB 250502A: TRT optical afterglow confirmation
  52. GRB 250430A: Enhanced Swift-XRT position
  53. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  54. GRB 250502A: SVOM detection of a burst
  55. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  56. GRB 250430A: KAIT optical observations
  57. GRB 250430A / EP250430a: J-band upper limits with WINTER
  58. GRB 250430A: DDOTI Optical Observations
  59. GRB 250430A: Leavitt Observatory optical upper limit
  60. GRB 250430A: Bassano Bresciano Observatory upper limit
  61. GRB 250430A : MITSuME Akeno optical upper limits
  62. SVOM/sb25043004: EP-FXT observations
  63. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  64. GRB 250430A: AKO Optical Afterglow Detection
  65. GRB 250430A: Kanata optical upper limit
  66. EP 250427A: Optical counterpart detection by LCO.
  67. GRB 250430A: Swift detection of a burst with optical counterpart
  68. EP250428b: FTW optical and NIR observations
  69. EP250427a/GRB250427A: HCT optical follow-up
  70. SVOM/sb25043004: SVOM detection of a X-ray transient
  71. EP250428b: GROWTH-India telescope optical upper limit
  72. EP250428b: SVOM/VT upper limit
  73. EP250428b: SAO RAS optical upper limit
  74. EP250428b: LAST optical upper limit
  75. GRB 250427A: Swift/UVOT Detection
  76. EP250428b: Einstein Probe detection of a fast X-ray transient
  77. EP250427A: COLIBRÍ Continuing Optical Observations
  78. GRB250427A/EP250427a GIT optical afterglow detection:
  79. EP250427a: LT optical counterpart detection
  80. GRB 250427A: Swift-XRT refined Analysis
  81. EP250427a / GRB 250427A: LCO optical counterpart detection
  82. EP250427a: REM optical/NIR afterglow detection
  83. GRB 250424A: LCO optical observation
  84. EP250427A: COLIBRÍ Optical Detection
  85. EP250427a: TRT optical counterpart detection
  86. EP250427a: Einstein Probe detection of a fast X-ray transient
  87. GRB 250424A: SVOM/GRM observation of a long burst
  88. GRB 250424A: PRIME near-infrared detection
  89. GRB 250424A: WINTER J-band detection
  90. GRB 250419A: Mondy Optical Observations
  91. GRB 250424A: Swift/UVOT Detection
  92. Konus-Wind detection of GRB 250424A
  93. GRB 250424A: Skynet Optical Observations
  94. GRB 250424A: Kilonova-Catcher optical afterglow detection
  95. GRB 250419A: Liverpool Telescope optical upper limit
  96. GRB 250424A: Enhanced Swift-XRT position
  97. GRB 250424A: AstroSat CZTI detection of a bright long burst
  98. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  99. GRB 250424A: BlackGEM optical afterglow detection
  100. GRB 250424A: DDOTI Afterglow Detection

Advanced

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