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"

3112 results found.

  1. SVOM GRB251219.11: Global MASTER-Net observations report
  2. Fermi trigger No 787736968: Global MASTER-Net observations report
  3. Fermi GRB 251216A: Global MASTER-Net observations report
  4. Fermi GRB 251215A: Global MASTER-Net observations report
  5. EP251214a: Global MASTER-Net observations report
  6. Fermi GRB 251214A: Global MASTER-Net observations report
  7. EP251212a: Global MASTER-Net observations report
  8. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  9. Fermi GBM Sub-Threshold Detection of GRB 251205A
  10. Fermi GRB 251208C: Global MASTER-Net observations report
  11. SVOM GRB251208D: Global MASTER-Net observations report
  12. GRB 251205A: COLIBRÍ optical observations
  13. GRB 251205A: Swift detection of a burst with an optical afterglow
  14. GRB 251203C: EP-FXT follow-up observation
  15. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  16. EP251130a: MAO/AZT-22 optical observations
  17. GRB 251201B: Swift detection of a burst with an optical counterpart
  18. EP251130a: SAO RAS optical observations
  19. EP251130a: Global MASTER-Net observations report
  20. GRB 251128A: SVOM/GRM observation of a long burst
  21. GRB 251128A: Fermi GBM Observation
  22. Fermi GRB 251128A: Global MASTER-Net observations report
  23. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  24. EP251118a: Optical detection with Kinder observations
  25. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  26. GRB 251119A: SVOM detection of a possible burst
  27. LAT GRB251118.86: Global MASTER-Net observations report
  28. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  29. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  30. GRB 251116C: LCO optical upper limits
  31. Fermi GRB 251115A: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  33. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  34. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  35. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  36. GRB 251112B: MAXI/GSC detection
  37. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  38. SVOM GRB251111.42: Global MASTER-Net observations report
  39. Fermi trigger No 784279167: Global MASTER-Net observations report
  40. SVOM GRB251106.83: Global MASTER-Net observations report
  41. GRB 251106A: MASTER optical observations
  42. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  43. Fermi GRB 251105A: Global MASTER-Net observations report
  44. GRB 251103B: MITSuME Akeno optical upper limits
  45. Fermi GRB 251103A: Global MASTER-Net observations report
  46. GRB 251103B: Swift detection of a burst
  47. GRB 251103A: BOOTES-2/TELMA optical afterglow
  48. GRB 251103A: NOT optical afterglow candidate
  49. Fermi GRB 251102A: Global MASTER-Net observations report
  50. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  51. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  52. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  53. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  54. EP251027.145: COLIBRÍ optical upper limits
  55. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  56. Fermi GRB 251026B: Global MASTER-Net observations report
  57. GRB 251025B: GROWTH-India Telescope optical observations
  58. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  60. GRB 251024A: Swift detection of a burst
  61. EP251023b: Global MASTER-Net observations report
  62. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  63. GRB 251013C: ISON-Castelgrande observatory optical observations
  64. Fermi GRB 251023A: Global MASTER-Net observations report
  65. GRB 251016B: Fermi GBM Detection
  66. IceCube-251018A: Global MASTER-Net observations report
  67. Fermi GRB 251016B: Global MASTER-Net observations report
  68. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  69. GRB 251013D: Swift-XRT observations
  70. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  71. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  72. GRB 251013C: SAO RAS optical observations
  73. Fermi GRB 251013A: Global MASTER-Net observations report
  74. GRB 251011B : MASTER optical observations
  75. SVOM/sb25101004: SVOM detection of a stellar flare
  76. IceCube Alert 251008A: Global MASTER-Net observations report
  77. GRB 251007B: SVOM/VT optical candidate
  78. EP251003a: LCO and VST fading optical counterpart
  79. Fermi GRB 251006B: Global MASTER-Net observations report
  80. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  81. Fermi GRB 251002A: Global MASTER-Net observations report
  82. Swift GRB 251001B: Global MASTER-Net observations report
  83. GRB 251001A: Fermi GBM Detection
  84. GRB 250925A: COLIBRÍ photometric redshift
  85. GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+
  86. GRB 250920C: COLIBRÍ optical observations
  87. Fermi GRB 250922B: Global MASTER-Net observations report
  88. GRB 250916A: CrAO ZTSh R-band optical observations
  89. GRB 250916A: SAO RAS Zeiss-1000 optical observations
  90. GRB 250920B: Swift/UVOT Detection
  91. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  92. GRB 250919A/EP250919a: SVOM/VT optical observation
  93. Fermi GRB 250918A: Global MASTER-Net observations report
  94. GRB 250919A: Fermi GBM Final Real-time Localization
  95. Fermi GRB 250910B: Global MASTER-Net observations report
  96. EP250910a: Global MASTER-Net observations report
  97. GRB 250905A: Swift-BAT refined analysis
  98. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  99. GRB250904A: Liverpool Telescope upper limits
  100. GRB 250905A: Enhanced Swift-XRT position

Advanced

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