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"

26537 results found.

  1. GRB 260120B: Fermi GBM Observation
  2. EP260105a: GTC/HiPERCAM optical observations
  3. GRB 260120B: Swift/UVOT Detection
  4. GRB 260120B: COLIBRÍ optical upper limits
  5. GRB 260120B: Enhanced Swift-XRT position
  6. GRB 260120B: SVOM/C-GFT optical counterpart detection
  7. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  8. GRB 260120B: Swift detection of a burst
  9. EP260119A: Mondy I-Band Observations
  10. GRB 260114A: Swift/UVOT Upper Limits
  11. EP260119a: Liverpool Telescope optical follow-up observations
  12. GRB 251202A: further radio observations with the VLA
  13. EP260119a: KAIT optical observations
  14. EP260119a: SVOM/VT optical observation
  15. EP260119a: update of EP-FXT follow-up observation
  16. EP260119a: NOT optical observations
  17. EP260119a: SAO RAS optical observations
  18. EP260116a: COLIBRÍ detection of a fading optical source
  19. GRB 251208D: SVOM/ECLAIRs refined analysis
  20. GRB 251208D: SVOM/ECLAIRs refined analysis
  21. GRB 260117A: Swift-XRT afterglow detection
  22. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  23. EP260119a: LCO optical observations
  24. GRB 260117A: ZTSh optical upper limit
  25. EP260119a: COLIBRÍ optical counterpart candidate
  26. EP260119a: preliminary result from the EP-FXT observation
  27. GRB 260110A: SVOM detection of a burst through offline search
  28. EP260119a: EP-WXT detection of a fast X-ray transient
  29. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  30. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  31. Swift trigger on the HMXB 1A 1118-61
  32. GRB 260117A: SVOM/C-GFT upper limit
  33. GRB 260117A: Swift-XRT observations
  34. GRB 260117A: SVOM detection of a long faint burst
  35. EP 260116a: COLIBRÍ optical upper limit
  36. Swift triggered on the HMXB 1A 1118-61
  37. GRB 260115A: GECAM-B observation
  38. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  39. EP260116a: Liverpool Telescope upper limits
  40. EP260116A: 1.3m DFOT optical upper limit
  41. GRB 260114A: VLT/MUSE spectroscopic observations
  42. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  44. EP260116a: Xinglong optical upper limit
  45. EP260116a: Einstein Probe detection of an X-ray transient
  46. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  47. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  48. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  49. GRB 251222A: radio detection with the VLA
  50. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  51. Konus-Wind detection of GRB 260114A
  52. GRB 260114A: Swift-XRT refined Analysis
  53. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  54. GRB 260114A : MITSuME Akeno optical upper limits
  55. GRB 260114A: COLIBRÍ optical upper limits
  56. GRB 260114A: TNG NIR upper limit
  57. GRB 260114A: NOT optical observations
  58. Konus-Wind detection of GRB 251230A / EP251230a
  59. GRB 260114A: SVOM/GRM observation of a short burst
  60. GRB 260114A: GECAM-B observation of a short burst
  61. GRB 260114A: Mondy optical observations
  62. GRB 260114A: Fermi GBM observation
  63. GRB 260114A: GMG Optical Observation
  64. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  65. GRB 260114A: Swift detection of a short burst
  66. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  67. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  68. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  69. EP260110a: TRT optical upper limits
  70. Konus-Wind detection of GRB 260101A
  71. GRB 260111A: Swift-XRT observations
  72. Swift Trigger 1439093: is probably not GRB 260113A
  73. GRB 260111A: COLIBRÍ optical afterglow candidate
  74. GRB 260111A: Fermi GBM Observation
  75. The EP-WXT trigger 01709251266 is likely a flaring star
  76. GRB 251230A: Mondy Optical Observations
  77. Swift trigger 1436759 is not an astrophysical event
  78. EP260110a: KAIT optical upper limit
  79. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  80. EP 260110a: COLIBRÍ optical observations
  81. EP260110a: SVOM/C-GFT upper limit
  82. EP260110a: Einstein Probe detection of an X-ray transient
  83. GRB 260109C: LCO optical upper limits
  84. GRB 260109C: Kilonova-Catcher optical upper limit
  85. Swift Trigger 1434591: possible GRB 260109C
  86. GRB 260102A: Swift-XRT afterglow detection
  87. GRB 260102A: AbAO optical observations
  88. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  89. The EP-WXT trigger 01709251112 is likely a flaring star
  90. GRB 260105B: Fermi GBM Detection
  91. GRB 260105A: SVOM/GRM observation
  92. GRB 260105B: SVOM/GRM observation
  93. The EP-WXT trigger 01709251028 is likely a flaring star
  94. FRB 20251229A: COLIBRÍ optical upper limits
  95. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  96. EP260105a: LCO Optical Upper limit
  97. EP260104a: Einstein Probe detection of a fast X-ray transient
  98. GRB 260101A: COLIBRÍ optical upper limits
  99. EP260105a: Einstein Probe detection of an X-ray transient
  100. GRB 260104A: COLIBRÍ optical upper limits

Advanced

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