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"

3137 results found.

  1. IPN triangulation of GRB 251016B
  2. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  3. Fermi GRB 251023A: Global MASTER-Net observations report
  4. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  5. GRB 251016A: Fermi GBM Observation
  6. GRB 251018A: Fermi GBM Observation
  7. IceCube-251018A: Global MASTER-Net observations report
  8. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  9. GRB 251016A: AstroSat CZTI detection of a short burst
  10. GRB 251016B: AstroSat CZTI detection
  11. GRB 251017A: Swift detection of a burst with an optical counterpart
  12. Fermi GRB 251016A: Global MASTER-Net observations report
  13. GRB 251013C: SVOM/ECLAIRs refined analysis
  14. GRB 251013D: Fermi GBM Observation
  15. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  16. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  17. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  18. GRB 251013C: AstroSat CZTI detection
  19. Fermi trigger No 782044789: Global MASTER-Net observations report
  20. Fermi GRB 251013C: Global MASTER-Net observations report
  21. GRB 251013C: BOOTES-6 early optical detection
  22. GRB 251013C: SVOM/VT optical observation
  23. GRB 251013C: SVOM detection of a burst
  24. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  25. GRB 251010A: AstroSat CZTI detection
  26. GRB 251011A: AstroSat CZTI detection
  27. EP251006a: Global MASTER-Net observations report
  28. IceCube Alert 251008A: Global MASTER-Net observations report
  29. GRB 251007A: AstroSat CZTI detection
  30. GRB 251007B: SVOM detection of a faint burst
  31. GRB 251006B/EP251006a: SVOM/VT optical candidate
  32. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  33. Fermi GRB 251006A: Global MASTER-Net observations report
  34. GRB 251005C: AstroSat CZTI detection
  35. GRB 251001A: AstroSat CZTI detection
  36. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  37. GRB 251002A: SVOM detection of a burst
  38. Fermi GRB 251002A: Global MASTER-Net observations report
  39. Fermi GRB 250929A: Global MASTER-Net observations report
  40. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  42. GRB 250926A: AstroSat CZTI detection
  43. GRB 250925A: Leavitt Observatory optical upper limit
  44. GRB 250924A: SAO RAS optical observations
  45. GRB 250924A: AstroSat CZTI detection
  46. GRB 250914A: AstroSat CZTI detection
  47. GRB 250920B: AstroSat CZTI detection
  48. GRB 250922C: AstroSat CZTI detection of a short burst
  49. Fermi trigger No 780156732: Global MASTER-Net observations report
  50. Swift GRB 250920C: Global MASTER-Net observations report
  51. Konus-Wind detection of GRB 250919A
  52. GRB 250920A: AstroSat CZTI detection
  53. EP250919a: Global MASTER-Net observations report
  54. Fermi GRB 250919A: Global MASTER-Net observations report
  55. GRB 250916A: SAO RAS optical observations
  56. GRB250917B: WFST optical observations
  57. GRB 250916A: AstroSat CZTI detection of a bright long burst
  58. Fermi GRB 250916A: Global MASTER-Net observations report
  59. Fermi GRB 250912A: Global MASTER-Net observations report
  60. EP250911a: Global MASTER-Net observations report
  61. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  62. Fermi GRB 250910B: Global MASTER-Net observations report
  63. EP250910a: Global MASTER-Net observations report
  64. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  65. GRB 250909B: AstroSat CZTI detection of a long burst
  66. GRB 250909A: AstroSat CZTI detection
  67. The EP-WXT trigger EP250908a/01709240652 is not a real source
  68. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  69. IceCube Alert 250905.84: Global MASTER-Net observations report
  70. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  73. EP250901a: Mondy, Assy and SAO RAS optical limits
  74. GRB 250902B: AstroSat CZTI detection
  75. Fermi GRB 250902B: Global MASTER-Net observations report
  76. EP250901a: Swift-XRT observations
  77. GRB 250901A: LCO optical upper limit
  78. EP250827b: Swift observations of AT 2025wkm
  79. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  80. EP250901a: Global MASTER-Net observations report
  81. GRB 250830C: AstroSat CZTI detection of a long burst
  82. EP250831a: Global MASTER-Net observations report
  83. EP250830a: Global MASTER-Net observations report
  84. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  86. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  87. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  88. GRB 250826A: Fermi GBM Final Real-time Localization
  89. Fermi GRB 250824B: Global MASTER-Net observations report
  90. GRB 250821B: AstroSat CZTI detection
  91. GRB 250819A: AstroSat CZTI detection
  92. LIGO/Virgo/KAGRA S250818k: GRAWITA TNG NIR observations of AT2025ulz
  93. GRB 250821C: Fermi GBM Final Real-time Localization
  94. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  95. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  96. GRB 250818A: AstroSat CZTI detection
  97. LIGO/Virgo/KAGRA S250818k: Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  98. GRB 250818C: Fermi GBM Final Real-time Localization
  99. Fermi trigger No 776849714: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate

Advanced

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