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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.

Lucene Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

23225 results found.

  1. EP250207b: NOT optical counterpart candidate
  2. GRB 250211B: A long GRB detected by INTEGRAL
  3. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  4. Integral GRB250211.89: Global MASTER-Net observations report
  5. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  6. GRB 250207A: Fermi GBM Observation
  7. GRB 250206A: Fermi GBM Observation
  8. GRB 250205A / EP250205A: radio detection with the VLA
  9. EP250207b: Tentative z-band brightening source
  10. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  11. Konus-Wind detection of GRB 250207A
  12. Konus-Wind detection of GRB 250206A
  13. GRB 250210A: SVOM/GRM observation of a long burst
  14. EP250207b: Liverpool Telescope possible optical counterpart
  15. EP250207b: Global MASTER-Net observations report
  16. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  18. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  19. GRB 250207A: Skynet optical afterglow observations
  20. GRB 241128A: VIRT Optical Upper Limit
  21. EP250207b: Gemini GMOS-N z-band observations
  22. GRB 250210A: AstroSat CZTI detection
  23. EP250207b: a new X-ray transient detected by Einstein Probe
  24. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  25. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  26. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  27. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  28. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  29. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  30. GRB 250207A: 1.3m DFOT Optical observations
  31. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  32. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  33. GRB 250129A: GRANDMA Continued Afterglow Detection
  34. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  35. GRB 250205A: 1.3m DFOT optical upper limit
  36. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  37. GRB 250207B: Swift-XRT observations
  38. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  39. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  40. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  41. EP250207a: EP-WXT detection and XRT follow-up observation
  42. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  43. GRB 250207A: Swift-XRT refined Analysis
  44. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  45. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  46. GRB 250207A: Enhanced Swift-XRT position
  47. 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%
  48. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  49. GRB 250207A: REM IR afterglow detection
  50. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  51. Konus-Wind detection of GRB 250204B
  52. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  53. GRB 250207A: REM optical afterglow detection
  54. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  56. GRB 250207A: Swift/UVOT Detection
  57. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  58. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  59. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  60. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  61. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  62. GRB 250129A: Continued AbAO and Mondy optical observations
  63. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  64. The EP-WXT trigger 01709131347 is likely a flaring star
  65. The EP-WXT trigger 01709131332 is likely a flaring star
  66. The EP-WXT trigger 01709131290 is likely a flaring star
  67. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  68. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  69. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  70. GRB 250207A: Swift detection of a burst with optical counterpart
  71. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  72. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  73. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  74. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  75. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  76. GRB 250205A: Fermi GBM Observation
  77. GRB 250205A: REM NIR upper limit
  78. GRB 250205A: Swift/UVOT Upper Limits
  79. LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
  80. EP250205a/GRB 250205A: Einstein Probe observation
  81. GRB 250127C: SVOM/GRM observation of a burst
  82. GRB 250204B: SVOM/GRM observation of a likely short burst
  83. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  84. GRB 250205A: Swift/XRT detection
  85. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  86. GRB250205A: SVOM/VT optical afterglow detection
  87. GRB 250205A: OHP/T193 optical counterpart candidate
  88. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  89. GRB 250205A: SVOM detection of a burst
  90. Konus-Wind detection of GRB 250201A
  91. IPN triangulation of GRB 250201A
  92. Konus-Wind detection of GRB 250202B
  93. LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
  94. IPN triangulation of GRB 250202B
  95. GRB 250129A: LCO late afterglow detection
  96. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  97. LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
  98. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  99. GRB 250202B: Fermi GBM Detection
  100. GRB 250129a: Liverpool Telescope optical follow-up

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