Skip to main content
Circulars over Kafka event name backfill. 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"

24704 results found.

  1. GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
  2. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  3. EP#01709176612: Swift-XRT counterpart detection of flaring star
  4. GRB 250521D: DDOTI Optical Upper Limit
  5. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  6. GRB 250521D: LAST tentative optical counterpart candidate
  7. GRB 250521A: DDOTI Optical Upper Limit
  8. GRB 250520A: VLT/FORS2 Optical Observation
  9. GRB 250502A: Tautenburg observations
  10. GRB 250520A: Swift/UVOT Upper Limits
  11. IPN triangulation of GRB 250516B
  12. GRB 250520A: J-band observations with WINTER
  13. GRB 250520A: Gemini-South optical observations
  14. GRB 250520A: Swift-XRT refined Analysis
  15. GRB 250520A: REM optical/NIR early observations
  16. GRB 250520A:SVOM/VT optical candidate
  17. GRB 250520A: COLIBRÍ optical upper limit
  18. GRB 250520A: DDOTI Optical Upper Limit
  19. GRB 250520A: AstroSat CZTI detection of a short burst
  20. GRB 250520A: Enhanced Swift-XRT position
  21. GRB 250520A: Swift detection of a burst
  22. GRB 250516A: Swift-BAT refined analysis
  23. GRB 250516A: COLIBRÍ optical upper limit
  24. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  25. GRB 250515A: Swift-XRT observations
  26. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  27. GRB 250515A: 1.6m Mephisto optical detection
  28. GRB 250516A: Fermi GBM Observation
  29. GRB 250516A: Swift-XRT refined Analysis
  30. GRB 250516A: Swift/UVOT Detection
  31. GRB 250516B: GECAM-B detection of a bright long burst
  32. GRB 250516A: Enhanced Swift-XRT position
  33. GRB 250516A: Swift detection of a burst
  34. MAXI GRB250515.65: Global MASTER-Net observations report
  35. GRB 250424A: COLIBRÍ detection of the associated supernova
  36. GRB 250502A: TESS observations
  37. GRB 250509A: Swift-BAT refined analysis
  38. Fermi GRB 250512A: Global MASTER-Net observations report
  39. EP250512a/GRB 250512B: REM optical/NIR observations
  40. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  41. GRB 250507B: AstroSat CZTI detection
  42. EP250511a: Gemini optical counterpart observation
  43. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  44. EP250511a: Mephisto optical upper limits
  45. GRB 250512B: SVOM detection of a burst
  46. EP250512a: Einstein Probe detection of an X-ray transient
  47. EP250511a: REM optical/NIR observations
  48. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  49. EP250511a: COLIBRÍ optical counterpart candidate
  50. EP250511a: BOOTES-5 optical upper limit
  51. EP250511a: Einstein Probe detection of an X-ray transient
  52. EP250508a: Gemini NIR upper limits
  53. GRB 250510B: Fermi GBM Observation
  54. GRB 250510A: Swift-XRT observations
  55. GRB 250509A: Fermi GBM Observation
  56. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  57. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  58. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  59. GRB 250509A: Swift-XRT refined Analysis
  60. GRB 250510A: SVOM possible detection of a burst
  61. GRB 250507A: J-band observations with WINTER
  62. GRB 250509A: Enhanced Swift-XRT position
  63. GRB 250509A: Swift detection of a burst
  64. GRB 250506A: NOT optical upper limits
  65. EP250508a: Liverpool Telescope optical upper limits
  66. EP250508a: KAIT optical upper limit
  67. GRB 250507A: KAIT optical upper limit
  68. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  69. GRB 250505B: SVOM/GRM observation of a short burst
  70. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  71. EP250508a: REM optical/NIR observations
  72. GRB 250506A: Swift-XRT afterglow detection
  73. EP250508a: COLIBRÍ Optical Limit
  74. EP250508a: Einstein Probe detection of an X-ray transient
  75. GRB 250507A: Swift-XRT refined Analysis
  76. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 250506A: Swift/UVOT Upper Limits
  78. GRB 250507A: follow-up observation with EP-FXT
  79. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  80. GRB 250507A: REM optical/NIR observations
  81. GRB 250507A: SVOM/VT optical upper limit
  82. GRB 250506A: Swift-XRT observations
  83. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  84. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  85. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  86. GRB 250507A: SVOM detection of a long burst
  87. GRB 250506A: Mephisto optical upper limits
  88. GRB 250504A: EIRSAT-1 GMOD Detection
  89. GRB 250502A: Bassano Bresciano Observatory upper limit
  90. GRB 250506A: Xinglong 2.16m optical upper limit
  91. SVOM/sb25050601: EP-FXT observations
  92. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  93. GRB 250506A: REM optical/NIR upper limits
  94. GRB 250506A: Fermi GBM Observation
  95. GRB 250506A: Swift XRT observations and possible counterpart detection
  96. GRB 250506A: TRT optical observations
  97. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  98. GRB 250506A: SVOM detection of a burst
  99. GRB 250504A: Swift-BAT refined analysis
  100. GRB 250430A: Swift-BAT refined analysis

Advanced

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