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"

3114 results found.

  1. GRB250904A: Liverpool Telescope upper limits
  2. GRB 250905A: Enhanced Swift-XRT position
  3. GRB 250905A: Swift detection of a burst
  4. GRB 250903A: Swift-XRT observations
  5. GRB 250903A: TRT optical counterpart detection
  6. GRB 250902B: AstroSat CZTI detection
  7. Fermi GRB 250902B: Global MASTER-Net observations report
  8. EP250827b: Liverpool Telescope observations
  9. Fermi GRB 250827A: Global MASTER-Net observations report
  10. GRB 250827A: Fermi GBM Final Real-time Localization
  11. EP250827a: BOOTES-7 early optical dectection
  12. EP250827a: Global MASTER-Net observations report
  13. Fermi GRB 250826A: Global MASTER-Net observations report
  14. Fermi trigger No 777883624: Global MASTER-Net observations report
  15. Fermi GRB 250824B: Global MASTER-Net observations report
  16. LIGO/Virgo/KAGRA S250818k: J-GEM follow-up observation for AT2025ulz
  17. IPN triangulation of GRB 250821B (long/bright)
  18. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  19. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  20. GRB 250820A: Fermi GBM Final Real-time Localization
  21. Fermi trigger No 776849714: Global MASTER-Net observations report
  22. LIGO/Virgo/KAGRA S250818k: Candidates from the Zwicky Transient Facility
  23. sb25081602: Swift-XRT observations
  24. SVOM/sb25081602: detection of a likely X-ray transient
  25. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  26. Fermi trigger No 776818276: Global MASTER-Net observations report
  27. Subject GRB 250813B: SVOM/MXT refined analysis
  28. EP250812a: SVOM/VT optical counterpart
  29. IceCube Alert 250813.14: Global MASTER-Net observations report
  30. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  31. GRB 250807A: AstroSat CZTI detection of bright long burst
  32. GRB 250807A: SVOM/VT optical observation
  33. GRB 250807A: Swift detection of a burst with an optical counterpart
  34. EP250730a: SVOM/VT optical upper limit
  35. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  36. EP250730a: Global MASTER-Net observations report
  37. GRB 250725A: Swift-BAT refined analysis
  38. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  39. GRB 250725A: SVOM/VT optical candidate
  40. GRB 250725A: Enhanced Swift-XRT position
  41. GRB 250725A: Swift detection of a burst
  42. Fermi GRB 250725A: Global MASTER-Net observations report
  43. GRB 250717B: SVOM/GRM observation
  44. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  45. GRB 250717B: Swift-XRT observations
  46. GRB 250716A: Fermi GBM Observation
  47. Fermi GRB 250715A: Global MASTER-Net observations report
  48. Fermi GRB 250714A: Global MASTER-Net observations report
  49. Fermi GRB 250711A: Global MASTER-Net observations report
  50. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  51. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  52. IPN triangulation of GRB 250703A
  53. GRB 250702B / EP2050702a: FTW optical and NIR observations
  54. Fermi GRB 250703A: Global MASTER-Net observations report
  55. GRB 250702F: Leavitt Observatory optical observations
  56. Fermi GRB 250702F: Global MASTER-Net observations report
  57. GRB 250628A: Swift-XRT refined Analysis
  58. Fermi GRB 250626A: Global MASTER-Net observations report
  59. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  60. Fermi trigger No 772190032: Global MASTER-Net observations report
  61. Konus-Wind detection of GRB 250620C
  62. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  63. GRB250620C: Fermi GBM Observation
  64. GRB 250620A: Fermi GBM Final Real-time Localization
  65. EP-WXT trigger 01709178975: GOTO optical upper limit
  66. Fermi trigger No 771752663: Global MASTER-Net observations report
  67. sb25061218: Swift-XRT observations
  68. GRB 250605A: Swift-BAT refined analysis
  69. GRB 250609A: Fermi GBM Observation
  70. Fermi trigger No 771072240: Global MASTER-Net observations report
  71. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  72. GRB 250609A: Fermi GBM Final Real-time Localization
  73. GRB 250605A: Enhanced Swift-XRT position
  74. Fermi GRB 250606A: Global MASTER-Net observations report
  75. The EP-WXT trigger 01709177873 is likely a flaring star
  76. GRB 250605A: LT optical observations
  77. GRB 250605A: Swift detection of a burst
  78. Fermi GRB 250601A: Global MASTER-Net observations report
  79. GRB 250602A: Fermi GBM Final Real-time Localization
  80. Fermi trigger No 770470765: Global MASTER-Net observations report
  81. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  82. GRB 250521D: LAST tentative optical counterpart candidate
  83. Fermi GRB 250516A: Global MASTER-Net observations report
  84. GRB 250515A: 1.6m Mephisto optical detection
  85. EP250512a: Global MASTER-Net observations report
  86. Fermi GRB 250510C: Global MASTER-Net observations report
  87. Fermi GRB 250510B: Global MASTER-Net observations report
  88. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  89. EP250508a: Global MASTER-Net observations report
  90. EP250508a: Einstein Probe detection of an X-ray transient
  91. IceCube Alert 250506.59: Global MASTER-Net observations report
  92. GRB 250504A: Swift-XRT refined Analysis
  93. EP250428b: SAO RAS optical upper limit
  94. EP250427a / GRB 250427A: LCO optical counterpart detection
  95. GRB 250424A: BlackGEM optical afterglow detection
  96. IceCube-250421A: DDOTI Detection of the LAST Candidate
  97. IceCube Alert 250421.71: Global MASTER-Net observations report
  98. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 250419A: MASTER optical afterglow observation
  100. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)

Advanced

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