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"

42564 results found.

  1. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  2. GRB 260827A: Fermi GBM Final Real-time Localization
  3. GRB 260818B: 6 GHz VLA observations
  4. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  5. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  6. GRB 260808B: SAO RAS observations of the optical rebrightening
  7. EP260822a: Global MASTER-Net observations report
  8. EP Alert 260820.31: Global MASTER-Net observations report
  9. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  10. GRB 260822A: SVOM/ECLAIRs refined analysis
  11. GRB 260809A: SVOM/ECLAIRs refined analysis
  12. GRB 260822A: SVOM/VT optical upper limits
  13. IceCube Alert 260825A: Global MASTER-Net observations report
  14. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 260825A: Fermi GBM Final Real-time Localization
  16. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  17. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  18. GRB 260822A: EP/FXT follow-up observations
  19. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  20. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  21. EP260822a: EP-FXT non-detection and upper limit
  22. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  23. GRB 260822A: GOTO optical counterpart detection
  24. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  25. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  26. EP260822a: Einstein Probe detection of a fast X-ray transient
  27. GRB 260822A: LCO optical upper limits
  28. The EP-WXT trigger 01709287395 is likely a flaring star
  29. GRB260822B: Fermi GBM Final Localization
  30. GRB 260822A: GROWTH-India Telescope Upper Limits
  31. GRB 260822A: GOTO optical upper limit
  32. GRB 260822A: SVOM detection of a short burst
  33. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  34. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  35. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 260818B: VLA radio observations
  37. GRB 260818B: SVOM/C-GFT optical upper limit
  38. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  39. IceCube Alert 260821A: Global MASTER-Net observations report
  40. The EP-WXT trigger 01709286204 is likely a flaring star
  41. GRB 260820A: Insight-HXMT/HE detection
  42. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  43. GRB 260818B: SVOM/GRM observation
  44. EP detected a brightening of LMXB 1ES 1735-26.9
  45. GRB260820A: Fermi GBM Final Real-Time Localization
  46. GRB 260818B: Insight-HXMT detection
  47. GRB 260818B: EP-FXT follow-up observation
  48. GRB 260818A: J-band observations with WINTER
  49. GRB 260818B: SVOM/ECLAIRs refined analysis
  50. GRB 260818A: SVOM/ECLAIRs refined analysis
  51. GRB 260818B: NOT optical upper limits
  52. GRB 260810A: SVOM/GRM observation
  53. GRB260818A: EP-FXT follow-up observation
  54. GRB 260818B: LCO optical upper limits
  55. GRB 260818B: SVOM detection of a short burst
  56. SVOM trigger sb26081806 is not a GRB
  57. EP260806a: SAO RAS multicolor optical observations
  58. GRB 260818A: LCO optical upper limits
  59. EP260812a: AbAO optical upper limit
  60. GRB 260810A: Insight-HXMT/HE detection
  61. GRB 260818A: SVOM possible detection of a long and faint GRB
  62. EP260806a: SVOM/ECLAIRs detection through targeted search
  63. EP260806a: NUTTELA-TAO optical observations
  64. The EP-WXT trigger 01709281429 is likely a flaring star
  65. EP260812a: AZT-22 optical upper limit
  66. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  67. The EP-WXT trigger 01709280562 is likely a flaring star
  68. EP260812b: Optical upper limit with Kinder
  69. The EP-WXT trigger 01709279838 is likely a flaring star
  70. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  71. GRB 260808B: Liverpool Telescope further optical observations
  72. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  73. GRB 260813A: Fermi GBM Final Real-time Localization
  74. EP260812a: NOT and Liverpool Telescope upper limits:
  75. EP260812b: Liverpool Telescope observations
  76. EP260812b: GOTO detection of the optical counterpart
  77. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  78. EP260812a: SVOM/C-GFT optical upper limit
  79. EP260812b: SVOM/VT optical observation
  80. GRB 260808A: SVOM/GRM observation
  81. EP260812b: Einstein Probe detection of an X-ray transient
  82. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  83. Fermi GBM Sub-Threshold Detection of GRB 260809A
  84. GRB 260810A: Glowbug gamma-ray detection
  85. GRB 260810A: AstroSat CZTI detection of a long burst
  86. EP260812a: Einstein Probe detection of an X-ray transient
  87. GRB 260809A: SAO RAS optical observations
  88. GRB 260808B: SAO RAS optical observations
  89. GRB 260808B: SVOM/VT optical re-brightening at day 3
  90. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  91. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  92. GRB 260808A: GECAM-B observation
  93. GRB 260807A: SVOM/ECLAIRs refined analysis
  94. EP260806a: MAO/AZT-22 optical observations
  95. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  96. GRB260808B: MAO/AZT-22 optical observations
  97. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  98. GRB 260809A: J-band upper limit with WINTER
  99. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  100. GRB 260806A: Glowbug gamma-ray detection

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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