Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

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"

21798 results found.

  1. EP250511a: Einstein Probe detection of an X-ray transient
  2. EP250508a: Gemini NIR upper limits
  3. GRB 250510A: Swift-XRT observations
  4. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  5. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  6. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  7. GRB 250507A: J-band observations with WINTER
  8. GRB 250509A: Enhanced Swift-XRT position
  9. GRB 250509A: Swift detection of a burst
  10. GRB 250506A: NOT optical upper limits
  11. EP250508a: Liverpool Telescope optical upper limits
  12. EP250508a: KAIT optical upper limit
  13. GRB 250507A: KAIT optical upper limit
  14. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  15. GRB 250505B: SVOM/GRM observation of a short burst
  16. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  17. EP250508a: REM optical/NIR observations
  18. GRB 250506A: Swift-XRT afterglow detection
  19. EP250508a: COLIBRÍ Optical Limit
  20. EP250508a: Einstein Probe detection of an X-ray transient
  21. GRB 250506A: Swift/UVOT Upper Limits
  22. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  23. GRB 250507A: REM optical/NIR observations
  24. GRB 250507A: SVOM/VT optical upper limit
  25. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  26. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  27. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  28. GRB 250507A: SVOM detection of a long burst
  29. GRB 250506A: Mephisto optical upper limits
  30. GRB 250502A: Bassano Bresciano Observatory upper limit
  31. GRB 250506A: Xinglong 2.16m optical upper limit
  32. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  33. GRB 250506A: REM optical/NIR upper limits
  34. GRB 250506A: TRT optical observations
  35. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  36. GRB 250504A: VLT/X-shooter upper limits
  37. GRB 250504A: REM optical/NIR observations
  38. GRB 250502A: REM optical/NIR observations
  39. GRB 250505A: Fermi GBM Final Real-time Localization
  40. GRB 250504A: MeerLICHT optical afterglow detection
  41. GRB 250504A: Enhanced Swift-XRT position
  42. GRB 250504A: Swift detection of a burst
  43. GRB 250502A: Swift/UVOT Follow up
  44. GRB 250502A: KAIT optical observations
  45. GRB 250502A: Montarrenti Observatory optical detection
  46. GRB 250502A: Swift-XRT afterglow detection
  47. GRB 250502A: NOT optical observations
  48. GRB 250502A: AKO Optical Afterglow Detection
  49. GRB 250502A: LCO optical counterpart detection
  50. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  51. GRB 250407A: VZLUSAT-2 detection
  52. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  53. GRB 250502B: DDOTI Optical Observations
  54. GRB 250502A: Early optical counterpart detection by LCO.
  55. GRB 250430A: Swift/UVOT Detection
  56. GRB 250502A: TRT optical afterglow confirmation
  57. GRB 250430A: Enhanced Swift-XRT position
  58. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  59. GRB 250502A: SVOM detection of a burst
  60. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  61. GRB 250430A: KAIT optical observations
  62. GRB 250430A / EP250430a: J-band upper limits with WINTER
  63. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  64. GRB 250430A: DDOTI Optical Observations
  65. GRB 250430A: Leavitt Observatory optical upper limit
  66. GRB 250430A: Bassano Bresciano Observatory upper limit
  67. GRB 250430A : MITSuME Akeno optical upper limits
  68. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  69. GRB 250430A: AKO Optical Afterglow Detection
  70. GRB 250430A: Kanata optical upper limit
  71. EP 250427A: Optical counterpart detection by LCO.
  72. GRB 250430A: Swift detection of a burst with optical counterpart
  73. EP250427a/GRB250427A: HCT optical follow-up
  74. SVOM/sb25043004: SVOM detection of a X-ray transient
  75. EP250428b: GROWTH-India telescope optical upper limit
  76. EP250428b: SAO RAS optical upper limit
  77. EP250428b: LAST optical upper limit
  78. GRB 250427A: Swift/UVOT Detection
  79. EP250428b: Einstein Probe detection of a fast X-ray transient
  80. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  81. EP250427A: COLIBRÍ Continuing Optical Observations
  82. GRB250427A/EP250427a GIT optical afterglow detection:
  83. EP250427a: LT optical counterpart detection
  84. EP250427a / GRB 250427A: LCO optical counterpart detection
  85. EP250427a: REM optical/NIR afterglow detection
  86. GRB 250424A: LCO optical observation
  87. EP250427A: COLIBRÍ Optical Detection
  88. EP250427a: TRT optical counterpart detection
  89. EP250427a: Einstein Probe detection of a fast X-ray transient
  90. GRB 250424A: SVOM/GRM observation of a long burst
  91. GRB 250424A: PRIME near-infrared detection
  92. GRB 250424A: WINTER J-band detection
  93. GRB 250419A: Mondy Optical Observations
  94. GRB 250424A: Swift/UVOT Detection
  95. Konus-Wind detection of GRB 250424A
  96. GRB 250424A: Skynet Optical Observations
  97. GRB 250424A: Kilonova-Catcher optical afterglow detection
  98. GRB 250407A: GRBAlpha detection
  99. GRB 250404A / EP250404a: GRBAlpha detection
  100. GRB 250330B: GRBAlpha 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