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"

45428 results found.

  1. EP#01709198415/EP250806a: Swift-XRT observations
  2. EP250806a: Global MASTER-Net observations report
  3. EP250802a: EP-FXT follow-up observation
  4. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  5. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  6. EP250806a: SVOM /VT optical candidate
  7. GRB 250806A: J-band upper limit from WINTER
  8. GRB 250805A: Swift-BAT refined analysis
  9. GRB 250806A: KAIT optical upper limit
  10. GRB 250806A: SVOM/VT refined analysis
  11. GRB 250806A: Swift-XRT counterpart detection
  12. EP250806a: COLIBRÍ optical upper limit
  13. GRB 250806A: Kilonova-Catcher optical upper limits
  14. EP250806a: Einstein Probe detection of an X-ray transient
  15. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. GRB 250806A: SVOM/VT optical upper limit
  17. GRB 250806A: SVOM detection of a soft burst
  18. GRB 250805A: SVOM/VT optical counterpart
  19. GRB 250805A: ESO/VLT observations
  20. GRB 250805A: Swift-XRT refined Analysis
  21. GRB 250804B: Swift-XRT observations
  22. GRB 250805A: Enhanced Swift-XRT position
  23. GRB 250804C: AstroSat CZTI detection of a long burst
  24. GRB 250805A: TRT optical upper limits
  25. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  26. GRB 250805A: Swift-XRT observations
  27. GRB 250805A: Swift detection of a burst
  28. Swift GRB250805.26: Global MASTER-Net observations report
  29. GRB 250804B: Tiled Swift observations
  30. Fermi trigger No 776041355: Global MASTER-Net observations report
  31. GRB 250804B: SVOM/GRM observation of a short burst
  32. GRB 250804A: Fermi GBM Final Localization
  33. EP250802a: additional Liverpool Telescope upper limits
  34. EP250730a: SVOM/VT optical upper limit
  35. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  36. EP250802a: Liverpool Telescope optical upper limits
  37. EP250802a: Global MASTER-Net observations report
  38. EP250802a: GROWTH-India Telescope optical upper limit
  39. EP250802a: Einstein Probe detection of an X-ray transient
  40. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  41. The EP-WXT trigger 01709198251 is likely a flaring star
  42. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  43. The EP-WXT trigger 01709198202 is likely a flaring star
  44. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  45. GRB 250702B: SMA observations
  46. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  47. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  48. EP250711a: CrAO and Assy optical observations
  49. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  50. EP250730a: Global MASTER-Net observations report
  51. EP250730a: COLIBRÍ optical upper limit
  52. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  53. EP250730a: Einstein Probe detection of an X-ray transient
  54. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  55. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  56. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  57. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  58. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  59. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  60. GRB 250725A: AstroSat CZTI detection
  61. GRB 250727A: EP-FXT follow-up observation
  62. GRB 250725A: PRIME near-infrared observations
  63. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  64. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  65. GRB: Clarification on Gamma-Ray Burst Naming Convention
  66. GRB 250728A: Swift-XRT observations
  67. GRB 250727A: SVOM/ECLAIRs refined analysis
  68. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  69. GRB 250728A: COLIBRÍ optical upper limit
  70. GRB 250728A: Fermi GBM Observation
  71. Fermi trigger No 775387550: Global MASTER-Net observations report
  72. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  73. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  74. GRB 250728A: Swift ToO observations
  75. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  76. GRB 250727A: AST3-2 Upper limit
  77. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  78. GRB 250727A: EP-FXT counterpart detection
  79. GRB250727A: SVOM/VT optical upper limit
  80. GRB 250727A: Swift-XRT observations
  81. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  84. GRB 250727A: SVOM detection of a burst
  85. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  86. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  87. The EP-WXT trigger 01709195487 is likely a flaring star
  88. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  89. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  90. GRB 250725A: Swift-XRT refined Analysis
  91. GRB 250725A: Fermi GBM Observation
  92. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  93. GRB 250725A: Swift-BAT refined analysis
  94. Konus-Wind detection of GRB 250725A
  95. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  96. GRB 250725A: SVOM/GRM observation
  97. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  98. GRB 250725A: Swift/UVOT Upper Limits
  99. GRB 250725A: Fermi-LAT detection
  100. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26

Advanced

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