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GCN at AAS 245, Legacy Circulars Address Retirement. 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').

23953 results found.

  1. EP250207b: Xinglong optical upper limit
  2. EP250212a: Xinglong optical upper limit
  3. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  4. EP250212a: Global MASTER-Net observations report
  5. GRB 250205A: VIRT Optical Upper Limit
  6. GRB 250205A: Leavitt Observatory optical upper limit
  7. EP250207B: Chandra localization of the X-ray counterpart
  8. EP250212a: Liverpool Telescope optical upper limits
  9. GRB250101A: Radio upper limits from GMRT observations
  10. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  11. EP250207B: GTC z-band Observations
  12. Fermi GRB 250212A: Global MASTER-Net observations report
  13. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  14. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  15. Fermi trigger No 760945500: Global MASTER-Net observations report
  16. EP250207b: NOT optical counterpart candidate
  17. GRB 250211B: A long GRB detected by INTEGRAL
  18. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  19. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  20. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  21. GRB 250207A: Fermi GBM Observation
  22. GRB 250206A: Fermi GBM Observation
  23. GRB 250205A / EP250205A: radio detection with the VLA
  24. EP250207b: Tentative z-band brightening source
  25. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  26. Konus-Wind detection of GRB 250206A
  27. GRB 250210A: SVOM/GRM observation of a long burst
  28. EP250207b: Liverpool Telescope possible optical counterpart
  29. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  30. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  31. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  32. GRB 250207A: Skynet optical afterglow observations
  33. GRB 241128A: VIRT Optical Upper Limit
  34. EP250207b: Gemini GMOS-N z-band observations
  35. EP250207A: Upper limits from Fermi-GBM Observations
  36. EP250207b: a new X-ray transient detected by Einstein Probe
  37. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  38. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  39. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  40. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  42. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  43. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  44. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  45. GRB 250207A: 1.3m DFOT Optical observations
  46. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  47. GRB 250206A: Swift-XRT observations
  48. GRB 250129A: GRANDMA Continued Afterglow Detection
  49. GRB 250207A: Swift-BAT refined analysis
  50. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  51. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  52. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  53. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  54. GRB 250205A: 1.3m DFOT optical upper limit
  55. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  56. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  57. GRB 250206A: EIRSAT-1 GMOD Detection
  58. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  59. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  60. GRB 250207B: Swift-XRT observations
  61. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  62. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  63. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  65. GRB 250207A: Swift-XRT refined Analysis
  66. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  67. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  68. GRB 250207A: Enhanced Swift-XRT position
  69. CHIME/FRB source FRB 20250206A detected less than 1 minute after LIGO-Virgo-Kagra (LVK) S250206dm, however the probability of spatial coincidence is order 0.1%
  70. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  71. GRB 250207A: REM IR afterglow detection
  72. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
  73. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  74. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  75. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  76. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  77. GRB 250207A: REM optical afterglow detection
  78. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  80. GRB 250207A: Swift/UVOT Detection
  81. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  82. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  83. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  84. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  85. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  86. GRB 250129A: Continued AbAO and Mondy optical observations
  87. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  88. GRB 250207B: MAXI/GSC detection
  89. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  90. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  91. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  92. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  93. GRB 250207A: Swift detection of a burst with optical counterpart
  94. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  95. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  96. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  97. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  98. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  99. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume

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