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"

32736 results found.

  1. GRB 251111A: SVOM/VT optical observations with VHF data
  2. GRB 251111A: KAIT optical upper limit
  3. GRB 251111A: LCO optical observation
  4. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  5. GRB 251103B: Swift-BAT refined analysis
  6. GRB 251106A: Swift/UVOT Upper Limits
  7. GRB 251105B: Insight-HXMT/HE detection
  8. GRB 251106B: Insight-HXMT detection
  9. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  10. GRB 251105A: AstroSat CZTI detection
  11. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  12. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  13. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  14. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  15. GRB 251102B: SVOM/GRM observation
  16. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  18. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  19. IPN triangulation of GRB 251105B (possible sGRB with EE)
  20. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  21. GRB 251106A: Swift-XRT afterglow detection
  22. GRB 251106A: Kilonova-Catcher optical upper limit
  23. Fermi GBM Sub-Threshold Detection of GRB 251106A
  24. GRB 251106A: Swift/BAT arcminute localization of a burst
  25. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  26. GRB 251106A: MASTER optical observations
  27. GRB 251103B: AstroSat CZTI detection
  28. GRB 251025C: TERI Gamma-ray detection
  29. GRB 251016B: TERI Gamma-ray detection
  30. GRB 251016A: TERI Gamma-ray detection of a short burst
  31. GRB 250920C: TERI Gamma-ray detection
  32. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  33. GRB 251105A: Fermi GBM Observation
  34. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  35. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  36. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  37. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  38. Fermi GBM Sub-Threshold Detection of GRB 251105B
  39. GRB 251103B: Swift/UVOT Upper Limits
  40. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  41. Fermi GRB 251105A: Global MASTER-Net observations report
  42. GRB 251103B: Fermi GBM observation
  43. GRB 251028A: Insight-HXMT/HE detection
  44. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  45. EP251102a: FTW optical and NIR observations
  46. GRB 251103A: WFST optical observations
  47. EP251102a: update of EP-FXT follow-up observation
  48. EP251102a: OHP/T193 optical observations
  49. GRB 251103A: OHP/T193 optical observations
  50. GRB 251103A: Xinglong 2.16m optical detection
  51. GRB 251103A: Insight-HXMT detection
  52. GRB 251103A: KAIT optical observations
  53. GRB 251103B: Nanshan/HMT optical upper limit
  54. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  55. GRB 251103B: MITSuME Akeno optical upper limits
  56. Fermi GRB 251103A: Global MASTER-Net observations report
  57. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  58. EP251102a: NIR observations with WINTER
  59. GRB 251103A: J-band detection with WINTER
  60. Swift GRB 251103B: Global MASTER-Net observations report
  61. GRB 251103B: GROWTH-India Telescope optical upper limits
  62. GRB 251103A: Kilonova-Catcher optical afterglow detection
  63. GRB 251103A: Swift/UVOT Detection
  64. GRB 251103A: Fermi GBM Observation
  65. GRB 251103A: SVOM/GRM observation
  66. GRB 251103A: Swift-XRT afterglow detection
  67. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  68. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  69. EP251102a: Einstein Probe detection of a fast X-ray transient
  70. GRB 251025B: OHP/T193 optical upper limit
  71. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  72. GRB 251103A: LCO optical observation
  73. GRB 251103A: GOTO optical afterglow detection
  74. GRB 251102A: AstroSat CZTI detection
  75. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  76. GRB 251103A: NOT spectroscopic redshift z = 0.76
  77. GRB 251103A: LCO optical afterglow detection
  78. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  79. GRB 251103A: NOT optical afterglow candidate
  80. Fermi GRB 251102A: Global MASTER-Net observations report
  81. GRB 251031A: Fermi GBM Observation
  82. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  83. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  84. Konus-Wind detection of GRB 251028A
  85. GRB 251025C: SVOM/GRM observation
  86. GRB 251028A: GECAM-B detection
  87. GRB 251028A: SVOM/GRM observation
  88. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  89. GRB 251028A: Fermi GBM Observation
  90. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  91. GRB 251022A: Swift-XRT confirmation of fading
  92. GRB 251026B: LBT near-infrared observations
  93. GRB 250926B: VZLUSAT-2 detection
  94. GRB 250926A: VZLUSAT-2 detection
  95. GRB 250925A: VZLUSAT-2 detection
  96. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  97. GRB 251026A/EP251026a: EP-FXT follow-up observation
  98. GRB 251028B: Fermi/GBM observation
  99. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  100. GRB 251028B: Glowbug gamma-ray detection

Advanced

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