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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.

Advanced Search Examples (click to copy):

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

14805 results found.

  1. GRB 260114A: Insight-HXMT/HE detection
  2. GRB 260122B: Swift detection of a burst
  3. EP260119a: Mondy and SAO RAS optical upper limits
  4. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  5. EP260116a: COLIBRÍ further observations
  6. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  7. GRB 260120B: Fermi GBM Observation
  8. EP260105a: GTC/HiPERCAM optical observations
  9. GRB 260120B: COLIBRÍ optical upper limits
  10. GRB 260101A: 239Alferov CubeSat detection
  11. EP260119a: Liverpool Telescope optical follow-up observations
  12. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  13. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  14. EP260119a: update of EP-FXT follow-up observation
  15. EP260119a: NOT optical observations
  16. EP260116a: COLIBRÍ detection of a fading optical source
  17. GRB 251208D: SVOM/ECLAIRs refined analysis
  18. GRB 251208D: SVOM/ECLAIRs refined analysis
  19. GRB 260117A: Swift-XRT afterglow detection
  20. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  21. GRB 260115A: AstroSat CZTI detection
  22. GRB 260117A: ZTSh optical upper limit
  23. EP260119a: COLIBRÍ optical counterpart candidate
  24. GRB 260110A: SVOM detection of a burst through offline search
  25. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  26. Swift trigger on the HMXB 1A 1118-61
  27. GRB 260117A: Swift ToO observations
  28. GRB 260117A: SVOM detection of a long faint burst
  29. EP 260116a: COLIBRÍ optical upper limit
  30. GRB 260115A: GECAM-B observation
  31. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  32. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  33. GRB 260114A: VLT/MUSE spectroscopic observations
  34. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  35. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  36. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  37. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  38. GRB260114A: STEP/T80S optical limits
  39. Konus-Wind detection of GRB 260114A
  40. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  41. GRB 260114A: COLIBRÍ optical upper limits
  42. GRB 260114A: TNG NIR upper limit
  43. GRB 260114A: NOT optical observations
  44. Konus-Wind detection of GRB 251230A / EP251230a
  45. GRB 260114A: SVOM/GRM observation of a short burst
  46. GRB 260114A: GECAM-B observation of a short burst
  47. GRB 260114A: Fermi GBM observation
  48. GRB 260112B: GECAM-B observation
  49. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  50. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  51. EP260110a: TRT optical upper limits
  52. Konus-Wind detection of GRB 260101A
  53. GRB 260111A: Swift-XRT observations
  54. Swift Trigger 1439093: is probably not GRB 260113A
  55. GRB 260111A: GECAM-B observation of a burst
  56. GRB 260111A: Fermi GBM Observation
  57. GRB 260111A: Swift ToO observations
  58. GRB 251230A: Mondy Optical Observations
  59. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  60. EP260110a: SVOM/VT optical upper limits
  61. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  62. EP260110a: KAIT optical upper limit
  63. EP 260110a: COLIBRÍ optical observations
  64. EP260110a: BOOTES-5/JGU optical upper limit
  65. GRB 260102A: Swift-XRT afterglow detection
  66. GRB 260105B: Fermi GBM Detection
  67. GRB 260105A: SVOM/GRM observation
  68. GRB 260105B: SVOM/GRM observation
  69. EP260105a: SVOM/VT optical upperlimit
  70. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  71. EP260105a: LCO Optical Upper limit
  72. EP260104a: Einstein Probe detection of a fast X-ray transient
  73. GRB 260103A: Insight-HXMT/HE detection
  74. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  75. GRB 260103A: GECAM-B observation of a burst
  76. GRB 260103A: SVOM/GRM observation of a possible GRB
  77. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  78. GRB 260102A: EP-FXT follow-up observation
  79. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  80. GRB 251230A / EP251230a: GECAM-B detection
  81. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  82. GRB 260102A: Swift ToO observations
  83. GRB 260101A: Fermi GBM Observation
  84. GRB 260102A: SVOM detection of a burst
  85. GRB 260101A: GECAM-B detection
  86. GRB 260101A: NOT spectroscopic observations
  87. GRB 260101A: SVOM/GRM observation
  88. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  89. GRB 251230A: GRANDMA/TAROT Early Detection
  90. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  91. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  92. EP251229a: BOOTES-2 early optical upper limit
  93. GRB 251230A: Early optical counterpart detection by LCO.
  94. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  95. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  96. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  97. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  98. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  99. GRB 251226A: SVOM/GRM observation
  100. GRB 251226A: GECAM-B detection

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