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"

21925 results found.

  1. Konus-Wind detection of GRB 250207A
  2. Konus-Wind detection of GRB 250206A
  3. GRB 250210A: SVOM/GRM observation of a long burst
  4. EP250207b: Liverpool Telescope possible optical counterpart
  5. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  6. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  7. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  8. GRB 250207A: Skynet optical afterglow observations
  9. GRB 241128A: VIRT Optical Upper Limit
  10. EP250207b: Gemini GMOS-N z-band observations
  11. EP250207b: a new X-ray transient detected by Einstein Probe
  12. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  13. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  14. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  15. GRB 250204B: GRBAlpha detection
  16. GRB 250204A: GRBAlpha detection
  17. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  18. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  19. GRB 250207A: 1.3m DFOT Optical observations
  20. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  21. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  22. GRB 250129A: GRANDMA Continued Afterglow Detection
  23. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  24. GRB 250205A: 1.3m DFOT optical upper limit
  25. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  26. GRB 250206A: Fermi-LAT detection
  27. GRB 250207B: Swift-XRT observations
  28. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  29. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  30. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  32. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  33. GRB 250207A: Enhanced Swift-XRT position
  34. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  35. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  36. GRB 250207A: REM IR afterglow detection
  37. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
  38. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  39. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  40. GRB 250207A: REM optical afterglow detection
  41. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  42. GRB 250207A: Swift/UVOT Detection
  43. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  44. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  45. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  46. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  47. GRB 250129A: Continued AbAO and Mondy optical observations
  48. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  49. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  50. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  51. GRB 250207A: Swift detection of a burst with optical counterpart
  52. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  53. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  54. GRB 250205A: Fermi GBM Observation
  55. GRB 250205A: REM NIR upper limit
  56. GRB 250205A: Swift/UVOT Upper Limits
  57. EP250205a/GRB 250205A: Einstein Probe observation
  58. GRB 250127C: SVOM/GRM observation of a burst
  59. GRB 250204B: SVOM/GRM observation of a likely short burst
  60. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  61. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  62. GRB250205A: SVOM/VT optical afterglow detection
  63. GRB 250205A: OHP/T193 optical counterpart candidate
  64. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  65. GRB 250205A: SVOM detection of a burst
  66. Konus-Wind detection of GRB 250201A
  67. IPN triangulation of GRB 250201A
  68. Konus-Wind detection of GRB 250202B
  69. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  70. IPN triangulation of GRB 250202B
  71. GRB 250129A: LCO late afterglow detection
  72. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  73. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  74. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  75. GRB 250202B: NuSTAR detection of the prompt emission
  76. GRB 250202C: GRBAlpha detection
  77. GRB 250202B: Fermi GBM Detection
  78. GRB 250129a: Liverpool Telescope optical follow-up
  79. GRB 240129A: further SAO RAS optical observations
  80. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  81. LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
  82. GRB 250129A: SVOM/C-GFT optical observations
  83. Swift GRB250129A: MASTER 4 days observations report
  84. GRB 250129A: 1.3m DFOT Optical observations
  85. GRB 250129A: Skynet Continued Optical Observations
  86. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  87. GRB 250129A: SAO RAS optical observations
  88. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  89. GRB 250129A: optical photometry from Konkoly
  90. GRB 250129A: COLIBRÍ Optical Observations
  91. GRB 250129A: iTelescope optical observation
  92. GRB 250129a: Liverpool Telescope optical follow-up
  93. GRB 250129A: TNG NIR afterglow detection
  94. GRB 250129A: AKO Optical Afterglow Detection
  95. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  96. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  97. GRB 250128B: VLA radio upper limit
  98. Ep250125A: 1.3m DFOT optical upper limit
  99. GRB 250129A: Skynet optical observations
  100. GRB 250128B: TNG optical upper limit

Advanced

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