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"

27050 results found.

  1. GRB 250920B: Fermi GBM Observation
  2. GRB 250920A: Fermi GBM Detection
  3. GRB 250920C: Fermi GBM Observation
  4. Swift GRB 250920C: Global MASTER-Net observations report
  5. GRB 250920B: Swift/UVOT Detection
  6. GRB 250920B: FTW optical and NIR observations of the counterpart
  7. GRB 250920C: Optical counterpart detection by LCO
  8. GRB 250920A: SVOM/GRM observation
  9. GRB250920C: LCOGT Optical Detection
  10. GRB 250920B: Swift-XRT refined Analysis
  11. GRB 250920B: SVOM/C-GFT optical observations
  12. GRB 250920C: GOTO optical counterpart candidate
  13. GRB 250919A / EP250919a: LCO optical observation
  14. GRB 250920C: Swift detection of a burst
  15. GRB 250920C: Fermi GBM Final Real-time Localization
  16. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  17. Swift GRB 250920B: Global MASTER-Net observations report
  18. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  19. GRB 250920B: Fermi GBM Final Real-time Localization
  20. GRB 250920A: BALROG localization (Fermi Trigger 780029651 / GRB 250920121)
  21. GRB 250920A: Fermi GBM Final Localization
  22. GRB 250919A/EP250919a: SVOM/VT optical observation
  23. GRB 250919A: Fermi GBM Observation
  24. Fermi GRB 250918A: Global MASTER-Net observations report
  25. GRB 250918A: SVOM/GRM observation
  26. GRB 250919A: Swift-XRT afterglow detection
  27. GRB 250919A: Fermi-LAT detection
  28. GRB 250919A: SVOM/GRM observation of a very bright GRB
  29. GRB 250919A: BALROG localization (Fermi Trigger 779934537 / GRB 250919020)
  30. EP250919a: Global MASTER-Net observations report
  31. EP250919a: Einstein Probe detection of an X-ray transient
  32. Correction for GCN 41877: EP-WXT ID is 01709243841
  33. The EP-WXT trigger 01709243841: Las Cumbres discovery of the optical counterpart
  34. GRB 250916A: Fermi GBM Observation
  35. Fermi GRB 250919A: Global MASTER-Net observations report
  36. GRB 250919A: Fermi GBM Final Real-time Localization
  37. GRB 250917B: VLT/HAWK-I near-infrared observations
  38. GRB 250912A: SVOM/ECLAIRs refined analysis
  39. GRB 250917B: Swift-BAT refined analysis
  40. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  41. GRB 250918A: BALROG localization (Fermi Trigger 779891543 / GRB 250918522)
  42. GRB 250918A: Fermi GBM Final Real-time Localization
  43. GRB 250917B: Swift/UVOT Upper Limits
  44. EP250916a: EP-FXT follow-up observation
  45. GRB 250916A : GIT optical observations
  46. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  47. GRB 250916A: Glowbug gamma-ray detection
  48. GRB 250917B: Fermi GBM Observation
  49. Fermi GRB 250917B: Global MASTER-Net observations report
  50. GRB 250917B: Swift detection of a short burst
  51. GRB 250916A: GOTO optical counterpart candidate
  52. GRB 250917B: Fermi GBM Final Real-time Localization
  53. GRB 250917A: Fermi GBM Final Real-time Localization
  54. The EP-WXT trigger 01709241037 is likely a flaring star
  55. GRB 250910A: SVOM/ECLAIRs refined analysis
  56. EP250916a: Einstein Probe detection of an X-ray transient
  57. Fermi GRB 250916A: Global MASTER-Net observations report
  58. GRB 250916A: Fermi GBM Final Real-time Localization
  59. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  60. SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
  61. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  62. SVOM/sb25091517: SVOM detection of an X-ray transient
  63. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  64. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  65. GRB 250912A: Swift-XRT observations
  66. GRB250912A: VLT/HAWK-I follow-up observations
  67. GRB 250912A: VLT observations
  68. GRB 250912A: Fermi GBM Observation
  69. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  70. GRB 250912A:SVOM/VT optical upper limit
  71. GRB 250912A: LCO optical upper limit
  72. The EP-WXT trigger 01709240768 is likely a flaring star
  73. Fermi GRB 250912A: Global MASTER-Net observations report
  74. EP250911a: Global MASTER-Net observations report
  75. GRB 250912A: SVOM detection of a burst
  76. GRB 250912A: Fermi GBM Final Real-time Localization
  77. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  78. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  79. EP250911a: Upper limit from Fermi-GBM Observations
  80. GRB 250911A: GECAM-B detection
  81. GRB 250911A: Swift-BAT refined analysis
  82. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  83. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  84. GRB 250910B: SVOM/GRM observation
  85. EP250911a: SVOM/VT optical observation
  86. GRB 250911A: Swift-XRT refined Analysis
  87. GRB 250910C: Fermi GBM Final Localization Correction
  88. EP250911a: Swift-XRT observations
  89. EP250911a: Optical detection with Kinder observations
  90. GRB 250911A: Swift/UVOT Detection
  91. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  92. GRB 250909B: SVOM/GRM observation
  93. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  94. EP250911a: COLIBRÍ optical observations
  95. Fermi GRB 250910B: Global MASTER-Net observations report
  96. EP250911a: LCO optical counterpart discovery
  97. EP250910a: Global MASTER-Net observations report
  98. EP250911a: Einstein Probe detection of an X-ray transient
  99. GRB 250903A: SVOM/ECLAIRs refined analysis
  100. GRB 250911A: Swift-XRT 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