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"

641 results found.

  1. Fermi GRB 260805A: Global MASTER-Net observations report
  2. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  3. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  4. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  5. GRB 260616A: AstroSat CZTI detection
  6. GRB 260616A: SVOM/GRM observation
  7. Fermi GRB 260523A: Global MASTER-Net observations report
  8. EP260509a: Global MASTER-Net observations report
  9. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  10. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  11. Fermi GRB 260310B: Global MASTER-Net observations report
  12. Fermi GRB 260221A: Global MASTER-Net observations report
  13. Fermi GRB 260219A: Global MASTER-Net observations report
  14. EP260209a: Global MASTER-Net observations report
  15. Fermi GRB 260208C: Global MASTER-Net observations report
  16. GRB 260208B: Fermi GBM Detection
  17. Konus-Wind detection of GRB 260128A / EP260128a
  18. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  19. EP260119a: SVOM/VT optical observation
  20. Swift trigger on the HMXB 1A 1118-61
  21. Swift triggered on the HMXB 1A 1118-61
  22. IceCube Alert 260111A: Global MASTER-Net observations report
  23. Swift GRB 251214B: Global MASTER-Net observations report
  24. SVOM GRB251211.12: Global MASTER-Net observations report
  25. GRB 251208A: SVOM/GRM observation of a short burst
  26. Fermi GRB 251127A: Global MASTER-Net observations report
  27. Fermi trigger No 784279167: Global MASTER-Net observations report
  28. GRB 251103A: NOT spectroscopic redshift z = 0.76
  29. Fermi GRB 251013A: Global MASTER-Net observations report
  30. GRB 250909A: AstroSat CZTI detection
  31. EP250901a: Mondy, Assy and SAO RAS optical limits
  32. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  33. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  34. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  35. GRB 250831A: Swift-XRT counterpart detection
  36. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. GRB 250831A: SVOM/VT upper limit with VHF data
  38. EP250711a: COLIBRÍ continuous optical observations
  39. IceCube-250708A: Global MASTER-Net observations report
  40. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  41. EP250610a: Global MASTER-Net observations report
  42. GRB 250516A: Swift-BAT refined analysis
  43. MAXI GRB250515.65: Global MASTER-Net observations report
  44. GRB 250430A: Swift-BAT refined analysis
  45. Fermi GRB 250502B: Global MASTER-Net observations report
  46. Fermi-LAT gamma-ray observations of IceCube-250421A
  47. GRB 250327A: Swift-XRT refined Analysis
  48. GRB 250327A: SVOM/VT optical candidate
  49. GRB 250322A: AstroSat CZTI detection of a short burst
  50. Fermi trigger No 763509110: Global MASTER-Net observations report
  51. Fermi GRB 250309B: Global MASTER-Net observations report
  52. GRB 250226A: Fermi GBM Observation
  53. Fermi GRB 250223A: Global MASTER-Net observations report
  54. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  55. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  56. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  57. GRB 250207A: REM IR afterglow detection
  58. GRB 250207A: REM optical afterglow detection
  59. GRB 250114B: OHP/T193 optical upper limit
  60. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  61. GRB 241207C: MASTER optical observations
  62. Fermi trigger No 755225799: Global MASTER-Net observations report
  63. Swift GRB 241128A: Global MASTER-Net observations report
  64. Swift GRB241127.91: Global MASTER-Net observations report
  65. GRB 241113A: Swift/UVOT Detection
  66. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  67. Fermi GRB 240918A: Global MASTER-Net observations report
  68. EP EP240913a: Global MASTER-Net observations report
  69. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  70. LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
  71. GRB 240829A: Swift-BAT refined analysis
  72. LAT GRB240828.62: Global MASTER-Net observations report
  73. Fermi trigger No 745866488: Global MASTER-Net observations report
  74. Fermi trigger No 745057312: Global MASTER-Net observations report
  75. Swift GRB 240811A: Global MASTER-Net observations report
  76. GRB 240727C: AstroSat CZTI detection of a long burst
  77. Konus-Wind detection of GRB 240627A
  78. Fermi GRB 240702A: Global MASTER-Net observations report
  79. Fermi trigger No 741211696: Global MASTER-Net observations report
  80. Swift Trigger 1232465: consistent with noise
  81. Konus-Wind detection of GRB 240529A
  82. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  83. GRB 240419B: Swift-BAT refined analysis
  84. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  85. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  86. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  87. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  88. Swift GRB 240419B: Global MASTER-Net observations report
  89. GRB 240414A: Swift-BAT refined analysis
  90. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  91. Fermi GRB 240408A: Global MASTER-Net observations report
  92. Konus-Wind detection of LXT 240402A/GRB 240402B
  93. Konus-Wind detection of GRB 240303B
  94. GRB 240222A: Swift/UVOT Upper Limits
  95. GRB 240109A: Swift-BAT refined analysis
  96. GRB 231215A: radio detection with the VLA
  97. GRB 231129A: Swift-BAT refined analysis
  98. GRB 231129A: BOOTES-5/JGT optical upper limit
  99. GRB 231118A: Swift-BAT refined analysis
  100. GRB 231111A: Swift-BAT refined analysis

Advanced

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