Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

44490 results found.

  1. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  2. GRB 260125B: Fermi GBM Final Real-time Localization
  3. GRB 260125A: Fermi GBM Final Real-time Localization
  4. GRB 260114A: SVOM/VT optical upper limits
  5. GRB 260120A: AstroSat CZTI detection
  6. GRB 260122B: Swift-BAT refined analysis
  7. GRB 260120B: SVOM/GRM observation
  8. GRB 260120A: GECAM-B observation
  9. GRB 260120B: AstroSat CZTI detection
  10. GRB 260114A: Insight-HXMT/HE detection
  11. GRB 260122B: Swift detection of a burst
  12. Swift GRB260122.97: Global MASTER-Net observations report
  13. EP260119a: Assy AZT-20 optical observations
  14. EP260119a: Mondy and SAO RAS optical upper limits
  15. GRB 260122A: Fermi GBM Final Real-time Localization
  16. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  17. EP260119a: Xinglong optical upper limit
  18. The EP-WXT trigger 01709251871 is likely a flaring star
  19. Fermi GRB 260120C: Global MASTER-Net observations report
  20. GRB 260120B: Swift-BAT refined analysis
  21. GRB 260120B: Swift-XRT refined Analysis
  22. EP260116a: COLIBRÍ further observations
  23. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  24. GRB 260120B: Fermi GBM Observation
  25. EP260105a: GTC/HiPERCAM optical observations
  26. GRB 260120B: Swift/UVOT Detection
  27. GRB 260120B: COLIBRÍ optical upper limits
  28. SVOM GRB260121.06: Global MASTER-Net observations report
  29. GRB 260120B: Enhanced Swift-XRT position
  30. GRB 260120B: SVOM/C-GFT optical counterpart detection
  31. GRB 260120C: Fermi GBM Final Real-time Localization
  32. GRB 260101A: 239Alferov CubeSat detection
  33. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  34. GRB 260120B: Swift detection of a burst
  35. Swift GRB260120B: Global MASTER-Net observations report
  36. GRB 260120B: Fermi GBM Final Real-time Localization
  37. EP260119A: Mondy I-Band Observations
  38. Fermi trigger No 790601190: Global MASTER-Net observations report
  39. Fermi trigger No 790570272: Global MASTER-Net observations report
  40. GRB 260114A: Swift/UVOT Upper Limits
  41. EP260119a: Liverpool Telescope optical follow-up observations
  42. GRB 251202A: further radio observations with the VLA
  43. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  44. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  45. EP260119a: KAIT optical observations
  46. GRB 260120A: Fermi GBM Final Real-time Localization
  47. EP260119a: SVOM/VT optical observation
  48. EP260119a: update of EP-FXT follow-up observation
  49. EP260119a: NOT optical observations
  50. EP260119a: SAO RAS optical observations
  51. SVOM GRB260119.92: Global MASTER-Net observations report
  52. SVOM GRB260119.92: Global MASTER-Net observations report
  53. SVOM GRB260119.90: Global MASTER-Net observations report
  54. EP260116a: COLIBRÍ detection of a fading optical source
  55. GRB 251208D: SVOM/ECLAIRs refined analysis
  56. GRB 251208D: SVOM/ECLAIRs refined analysis
  57. GRB 260117A: Swift-XRT afterglow detection
  58. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  59. EP260119a: Global MASTER-Net observations report
  60. GRB 260115A: AstroSat CZTI detection
  61. EP260119a: LCO optical observations
  62. GRB 260117A: ZTSh optical upper limit
  63. EP260119a: COLIBRÍ optical counterpart candidate
  64. EP260119a: preliminary result from the EP-FXT observation
  65. GRB 260110A: SVOM detection of a burst through offline search
  66. EP260119a: EP-WXT detection of a fast X-ray transient
  67. Swift GRB260118.48: Global MASTER-Net observations report
  68. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  69. SVOM GRB260117.82: Global MASTER-Net observations report
  70. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  71. Swift trigger on the HMXB 1A 1118-61
  72. GRB 260117A: SVOM/VT optical candidate
  73. GRB 260117A: SVOM/C-GFT upper limit
  74. GRB 260117A: Swift-XRT observations
  75. GRB 260117A: Swift ToO observations
  76. GRB 260117A: SVOM detection of a long faint burst
  77. EP 260116a: COLIBRÍ optical upper limit
  78. Swift triggered on the HMXB 1A 1118-61
  79. GRB 260115A: GECAM-B observation
  80. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  81. EP260116a: Liverpool Telescope upper limits
  82. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  83. EP260116A: 1.3m DFOT optical upper limit
  84. GRB 260114A: VLT/MUSE spectroscopic observations
  85. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  86. EP260116a: Global MASTER-Net observations report
  87. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  88. EP260116a: Xinglong optical upper limit
  89. EP260116a: Einstein Probe detection of an X-ray transient
  90. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  91. IceCube Alert 260115.73: Global MASTER-Net observations report
  92. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  93. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  94. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  95. Fermi GRB 260115A: Global MASTER-Net observations report
  96. GRB 260115A: Fermi GBM Final Real-time Localization
  97. GRB260114A: STEP/T80S optical limits
  98. GRB 251222A: radio detection with the VLA
  99. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  100. Konus-Wind detection of GRB 260114A

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov