Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

43053 results found.

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