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"

2411 results found.

  1. GRB 251007A: NOT optical observations
  2. GRB 251006B: Insight-HXMT detection
  3. GRB 251007A: SVOM/C-GFT optical observations
  4. GRB 251005C: PRIME J-band upper limit
  5. GRB 251007B: SVOM/C-GFT upper limit
  6. GRB 251007B: SVOM detection of a faint burst
  7. GRB 251006B/EP251006a: SVOM/VT optical candidate
  8. GRB 251006B: SVOM/GRM observation
  9. GRB 251005C: SVOM/VT optical fading
  10. GRB 251005C: SVOM/GRM observation of a likely short GRB
  11. GRB 251005C: VLT/X-shooter Imaging
  12. GRB 251002A: LAST optical observations
  13. GRB 251005C: SVOM/VT optical candidate
  14. GRB 250902A: MSU cubesats detection
  15. GRB 251002A: Mondy/AZT-33IK optical observations
  16. GRB 251002A: Insight-HXMT detection
  17. GRB 251002A: Insight-HXMT detection
  18. Fermi GBM Sub-Threshold Detection of GRB 250910A
  19. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  20. GRB 251002A: Swift/UVOT detection
  21. GRB 251002A: Fermi GBM Observation
  22. GRB 251001C: SVOM/GRM observation
  23. GRB 251002A: AKO Early Optical Afterglow Detection
  24. GRB 251002A: Swift-XRT afterglow detection
  25. GRB 251002A: Kilonova-Catcher optical afterglow detection
  26. GRB 251002A: AbAO optical observations
  27. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  28. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  29. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  30. GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
  31. GRB 251002A: EP-FXT counterpart detection
  32. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  33. GRB 251002A: BOOTES-6 early optical detection
  34. GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  35. GRB 251002A: LCO optical observation
  36. GRB 251002A: SVOM/VT optical observation
  37. GRB 251002A: SVOM detection of a burst
  38. GRB 251001A: SVOM/GRM observation
  39. GRB 251001B: SVOM/VT optical observation
  40. GRB 250930A: SVOM/GRM observation
  41. GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592
  42. GRB 250916A: SVOM/VT optical observation
  43. GRB 250924A: SVOM/GRM observation
  44. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  45. GRB 250925A: SVOM/GWAC-F60A upper limit
  46. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  47. GRB 250922A: SVOM/GRM observation
  48. GRB 250924A: SVOM/VT optical observation
  49. GRB 250920C: Kilonova-Catcher optical afterglow detection
  50. GRB 250922B: SVOM/GRM observation
  51. GRB 250919A / EP250919a: further LCO optical observation
  52. Konus-Wind detection of GRB 250920C
  53. GRB 250920C: KAIT optical observations
  54. GRB 250920C: COLIBRÍ optical observations
  55. GRB 250920C: NIR observations with WINTER
  56. Konus-Wind detection of GRB 250920A
  57. IPN triangulation of GRB 250920A (long/bright)
  58. GRB 250920C: SVOM/GRM observation
  59. GRB 250920A: NuSTAR detection of bright prompt emission
  60. GRB 250920B: Fermi GBM Observation
  61. GRB 250920A: Fermi GBM Detection
  62. GRB 250920A: SVOM/GRM observation
  63. GRB 250920B: SVOM/C-GFT optical observations
  64. GRB 250919A / EP250919a: LCO optical observation
  65. Konus-Wind detection of GRB 250919A
  66. GRB 250919A / EP250919a: Insight-HXMT detection
  67. GRB 250919A/EP250919a: SVOM/VT optical observation
  68. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  69. GRB 250919A: Glowbug gamma-ray detection
  70. GRB 250919A: Fermi GBM Observation
  71. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  72. GRB 250918A: SVOM/GRM observation
  73. GRB 250919A: Fermi-LAT detection
  74. EP250919a/GRB 250919A: Gemini/GMOS-S spectroscopic redshift z = 1.145
  75. GRB 250919A: SVOM/GRM observation of a very bright GRB
  76. GRB 250912A: SVOM/ECLAIRs refined analysis
  77. GRB 250910A: SVOM/ECLAIRs refined analysis
  78. SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
  79. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  80. SVOM/sb25091517: SVOM detection of an X-ray transient
  81. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  82. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  83. GRB 250912A: Swift-XRT observations
  84. GRB250912A: VLT/HAWK-I follow-up observations
  85. GRB 250912A: VLT observations
  86. GRB 250912A: Fermi GBM Observation
  87. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  88. GRB 250912A:SVOM/VT optical upper limit
  89. GRB 250912A: LCO optical upper limit
  90. GRB 250912A: SVOM detection of a burst
  91. GRB 250910B: SVOM/GRM observation
  92. EP250911a: SVOM/VT optical observation
  93. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  94. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  95. GRB 250909B: Insight-HXMT detection
  96. GRB 250909B: SVOM/GRM observation
  97. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  98. GRB 250903A: SVOM/ECLAIRs refined analysis
  99. GRB 250910A: SVOM/VT optical upper limit
  100. GRB 250910A: LCO optical upper limit

Advanced

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