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"

18353 results found.

  1. Swift trigger on the HMXB 1A 1118-61
  2. GRB 260117A: SVOM/C-GFT upper limit
  3. EP 260116a: COLIBRÍ optical upper limit
  4. Swift triggered on the HMXB 1A 1118-61
  5. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  6. EP260116a: Liverpool Telescope upper limits
  7. EP260116A: 1.3m DFOT optical upper limit
  8. GRB 260114A: VLT/MUSE spectroscopic observations
  9. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  10. EP260116a: Xinglong optical upper limit
  11. EP260116a: Einstein Probe detection of an X-ray transient
  12. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  13. Fermi GRB 260115A: Global MASTER-Net observations report
  14. GRB 251222A: radio detection with the VLA
  15. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  16. GRB 260114A: Swift-XRT refined Analysis
  17. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  18. GRB 260114A : MITSuME Akeno optical upper limits
  19. GRB 260114A: COLIBRÍ optical upper limits
  20. GRB 260114A: TNG NIR upper limit
  21. GRB 260114A: NOT optical observations
  22. GRB 260114A: SVOM/GRM observation of a short burst
  23. GRB 260114A: Mondy optical observations
  24. GRB 260114A: GMG Optical Observation
  25. GRB 260114A: Swift detection of a short burst
  26. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  27. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  28. EP260110a: TRT optical upper limits
  29. Swift Trigger 1439093: is probably not GRB 260113A
  30. GRB 260111A: COLIBRÍ optical afterglow candidate
  31. The EP-WXT trigger 01709251266 is likely a flaring star
  32. GRB 260111A: GOTO optical upper limits
  33. GRB 251230A: Mondy Optical Observations
  34. Swift trigger 1436759 is not an astrophysical event
  35. EP260110a: KAIT optical upper limit
  36. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  37. EP 260110a: COLIBRÍ optical observations
  38. EP260110a: SVOM/C-GFT upper limit
  39. EP260110a: Einstein Probe detection of an X-ray transient
  40. GRB 260109C: LCO optical upper limits
  41. GRB 260109C: Kilonova-Catcher optical upper limit
  42. Swift Trigger 1434591: possible GRB 260109C
  43. GRB 260109B: Fermi GBM Final Real-time Localization
  44. GRB 260102A: Swift-XRT afterglow detection
  45. GRB 260109A: Fermi GBM Final Real-time Localization
  46. GRB 260102A: AbAO optical observations
  47. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  48. The EP-WXT trigger 01709251112 is likely a flaring star
  49. GRB 260105A: SVOM/GRM observation
  50. GRB 260105B: SVOM/GRM observation
  51. The EP-WXT trigger 01709251028 is likely a flaring star
  52. FRB 20251229A: COLIBRÍ optical upper limits
  53. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  54. EP260105a: LCO Optical Upper limit
  55. EP260104a: Einstein Probe detection of a fast X-ray transient
  56. GRB 260101A: COLIBRÍ optical upper limits
  57. EP260105a: Einstein Probe detection of an X-ray transient
  58. GRB 260104A: COLIBRÍ optical upper limits
  59. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  60. GRB 260104A: Enhanced Swift-XRT position
  61. GRB 260101A: Swift/UVOT Detection
  62. GRB 260104A: Swift detection of a burst
  63. GRB 260101A: COLIBRÍ optical observations
  64. SVOM GRB260103.08: Global MASTER-Net observations report
  65. GRB 260102A: EP-FXT follow-up observation
  66. GRB 260102A: LCO optical upper limits
  67. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  68. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  69. GRB 260102A: SVOM detection of a burst
  70. GRB 260101A: SVOM/GRM observation
  71. GRB 260101A: Enhanced Swift-XRT position
  72. EP260101a: Einstein Probe detection of an X-ray transient
  73. GRB 260101A: LCO detection of the optical counterpart
  74. GRB 260101A: Swift detection of a burst with an optical counterpart
  75. GRB 251230A: GRANDMA/TAROT Early Detection
  76. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  77. EP251229a: Optical upper limit with Kinder observations
  78. GRB 251230A: 1.3m DFOT optical upper limit
  79. GRB 251222A: Mondy Optical Observations
  80. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  81. GRB 251230A: Swift/UVOT detection
  82. GRB251230A: 7DT optical upper limits
  83. GRB 251230A: GOTO optical upper limit
  84. EP251229a: NOT optical upper limits
  85. GRB 251230A / EP251230a: SVOM/VT optical observation
  86. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  87. GRB 251230A: Enhanced Swift-XRT position
  88. GRB 251230A: Early optical counterpart detection by LCO.
  89. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  90. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  91. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  92. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  93. EP251229a: Einstein Probe detection of an X-ray transient
  94. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  95. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  96. The EP-WXT trigger 01709250662 is likely a flaring star
  97. GRB 251226A: SVOM/GRM observation
  98. The EP-WXT trigger 01709250617 is likely a flaring star
  99. GRB 251222A/EP251222b: Optical detection with Kinder observations
  100. EP251222a: Optical upper limit with Kinder observations

Advanced

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