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"

28053 results found.

  1. GRB 250807A: Swift-XRT refined Analysis
  2. GRB 250806A: SVOM/MXT refined analysis
  3. EP250807a: NTT z-band optical upper limit
  4. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  5. GRB 250807A: SVOM/GRM observation
  6. GRB 250807A: AstroSat CZTI detection of bright long burst
  7. GRB 250807B: Swift-XRT refined Analysis
  8. EP250807a: EP-WXT detection of a fast X-ray transient
  9. EP 250807.979: GOTO optical upper limit
  10. EP250807a: COLIBRÍ optical upper limit
  11. EP250806a: Upper limit from Fermi-GBM Observations
  12. GRB 250807B: Enhanced Swift-XRT position
  13. GRB 250807A: Enhanced Swift-XRT position
  14. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 250807B: Swift detection of a burst with an optical counterpart.
  16. GRB 250805A: Kilonova-Catcher optical upper limits
  17. GRB 250805A: Swift/UVOT Upper Limits
  18. GRB 250806A: Swift/UVOT U-band detection
  19. EP250806a: Liverpool telescope optical upper limit
  20. GRB 250807A: Swift detection of a burst with an optical counterpart
  21. EP250802a: EP-FXT follow-up observation
  22. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  23. EP250806a: SVOM /VT optical candidate
  24. GRB 250806A: J-band upper limit from WINTER
  25. GRB 250805A: Swift-BAT refined analysis
  26. GRB 250806A: KAIT optical upper limit
  27. GRB 250806A: Swift-XRT counterpart detection
  28. EP250806a: COLIBRÍ optical upper limit
  29. GRB 250806A: Kilonova-Catcher optical upper limits
  30. EP250806a: Einstein Probe detection of an X-ray transient
  31. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  32. GRB 250806A: SVOM/VT optical upper limit
  33. GRB 250806A: SVOM detection of a soft burst
  34. GRB 250805A: SVOM/VT optical counterpart
  35. GRB 250805A: Swift-XRT refined Analysis
  36. GRB 250804B: Swift-XRT observations
  37. GRB 250805A: Enhanced Swift-XRT position
  38. GRB 250805A: TRT optical upper limits
  39. GRB 250805A: Swift-XRT observations
  40. GRB 250804B: SVOM/GRM observation of a short burst
  41. GRB 250804A: Fermi GBM Final Localization
  42. EP250802a: additional Liverpool Telescope upper limits
  43. EP250730a: SVOM/VT optical upper limit
  44. EP250802a: Liverpool Telescope optical upper limits
  45. EP250802a: Global MASTER-Net observations report
  46. EP250802a: GROWTH-India Telescope optical upper limit
  47. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  48. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  50. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  51. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  52. EP250711a: CrAO and Assy optical observations
  53. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  54. EP250730a: COLIBRÍ optical upper limit
  55. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  56. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  57. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  58. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  59. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  60. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  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 250728A: Swift-XRT observations
  66. GRB 250728A: COLIBRÍ optical upper limit
  67. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  68. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  69. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  70. GRB 250727A: EP-FXT counterpart detection
  71. GRB 250727A: Swift-XRT observations
  72. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  75. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  76. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  77. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  78. GRB 250725A: Swift-XRT refined Analysis
  79. GRB 250725A: Fermi GBM Observation
  80. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  81. GRB 250725A: Swift-BAT refined analysis
  82. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  83. GRB 250725A: SVOM/GRM observation
  84. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  85. GRB 250725A: Swift/UVOT Upper Limits
  86. GRB 250725A: Fermi-LAT detection
  87. GRB 250725A: BOOTES-7 early optical detection
  88. GRB 250725A: SVOM/VT optical candidate
  89. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  90. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  92. GRB 250725A: Enhanced Swift-XRT position
  93. GRB 250725A: Swift detection of a burst
  94. Swift GRB 250725A: Global MASTER-Net OT detection
  95. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  96. SVOM J195836+32283 is not a real source
  97. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  98. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  99. GRB 250721A: Fermi GBM Observation
  100. SVOM J195836+32283/sb25072103: NIR observations with WINTER

Advanced

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