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"

20960 results found.

  1. EP250212a: Global MASTER-Net observations report
  2. GRB 250205A: Leavitt Observatory optical upper limit
  3. EP250207B: Chandra localization of the X-ray counterpart
  4. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  5. EP250207b: VLA radio upper limits
  6. GRB250101A: Radio upper limits from GMRT observations
  7. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  8. EP250207B: GTC z-band Observations
  9. Fermi GRB 250212A: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  11. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  12. Fermi trigger No 760945500: Global MASTER-Net observations report
  13. EP250207b: NOT optical counterpart candidate
  14. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  15. GRB 250211A: Swift ToO observations
  16. Integral GRB250211.89: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  18. GRB 250205A / EP250205A: radio detection with the VLA
  19. IceCube-250207A: One candidate from the Zwicky Transient Facility
  20. EP250207b: Tentative z-band brightening source
  21. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  22. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  23. EP250207b: Liverpool Telescope possible optical counterpart
  24. EP250207b: Global MASTER-Net observations report
  25. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  26. GRB 250207A: Skynet optical afterglow observations
  27. LIGO/VIRGO/KAGRA S250206dm: AT 2025bbo spectroscopic observations with NIRES on Keck II
  28. LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
  29. EP250207b: Gemini GMOS-N z-band observations
  30. EP250207A: Upper limits from Fermi-GBM Observations
  31. GRB 250210A: INTEGRAL SPI-ACS detection
  32. EP250207b: a new X-ray transient detected by Einstein Probe
  33. Fermi GRB 250210A: Global MASTER-Net observations report
  34. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  35. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  36. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  37. IceCube Alert 250207.09: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  39. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  40. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  41. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  42. GRB 250207A: 1.3m DFOT Optical observations
  43. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  44. GRB 250206A: Swift-XRT observations
  45. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  46. GRB 250129A: GRANDMA Continued Afterglow Detection
  47. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  48. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  49. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  50. GRB 250205A: 1.3m DFOT optical upper limit
  51. GRB 250206A: Tiled Swift observations
  52. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  53. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  54. GRB 250207B: Swift-XRT observations
  55. IceCube-250203A: No transient candidates from the Zwicky Transient Facility
  56. LIGO/Virgo/KAGRA S250206dm: Spectroscopic Classification of AT2025bay and AT2025baz with Keck I/LRIS
  57. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  58. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  59. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  60. EP-WXT trigger 01709131361: correction to GCN 39214
  61. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  62. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  63. EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
  64. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  65. GRB 250207A: REM IR afterglow detection
  66. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
  67. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  68. GRB 250207A: FRAM-Auger optical detection
  69. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  70. GRB 250207B: Tiled Swift observations
  71. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  72. GRB 250207A: REM optical afterglow detection
  73. GRB 250207A: Swift/UVOT Detection
  74. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  75. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  76. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  77. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  78. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  79. GRB 250129A: Continued AbAO and Mondy optical observations
  80. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  81. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  82. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  83. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  84. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  85. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  86. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  87. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  88. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  89. GRB 250205A: REM NIR upper limit
  90. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  91. GRB 250205A: Swift/UVOT Upper Limits
  92. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  93. GRB 250205A: Swift/XRT detection
  94. GRB 250205A: GOTO optical upper limits
  95. GRB 250205A: OHP/T193 optical counterpart candidate
  96. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  97. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  98. EP 250108A: Upper limits from Fermi-GBM Observations
  99. GRB 250129A: LCO late afterglow detection
  100. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations

Advanced

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