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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"

38399 results found.

  1. GRB 260827A: SVOM/GRM observation
  2. NuSTAR 260828: a 1100s hard X-ray transient
  3. GRB 260831B: SVOM detection of a possible burst
  4. IPN triangulation of GRB 260829A
  5. GRB 260827A: Glowbug gamma-ray detection
  6. EP260727a: ATCA 10 GHz detection
  7. GRB 260831A: Fermi GBM Final Real-time Localization
  8. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  9. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  10. GRB 260829A: GECAM-B observation of a long burst
  11. GRB 260825A: SVOM/GRM observation of a long burst
  12. GRB 260825A: GECAM-B observation
  13. GRB 260829A: Fermi GBM Detection
  14. GRB 260825A: AstroSat CZTI detection
  15. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  16. GRB 260829A: Fermi GBM Final Real-time Localization
  17. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  18. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  19. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  20. Fermi GBM trigger 809666623/260829141 is not a GRB
  21. GRB 260818B: Further EP-FXT observation
  22. GRB 260818B: VLT optical and nIR observations
  23. GRB 260818B: TNG NIR observations
  24. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  25. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  26. GRB 260827A: Fermi GBM Final Real-time Localization
  27. GRB 260818B: 6 GHz VLA observations
  28. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  29. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  30. GRB 260808B: SAO RAS observations of the optical rebrightening
  31. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  32. GRB 260807A: EP-FXT follow-up observations
  33. GRB 260822A: SVOM/ECLAIRs refined analysis
  34. GRB 260809A: SVOM/ECLAIRs refined analysis
  35. GRB 260822A: SVOM/VT optical upper limits
  36. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 260825A: Fermi GBM Final Real-time Localization
  38. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  39. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  40. GRB 260822A: EP/FXT follow-up observations
  41. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  42. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  43. EP260822a: EP-FXT non-detection and upper limit
  44. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  45. GRB 260822A: GOTO optical counterpart detection
  46. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  47. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  48. EP260822a: Einstein Probe detection of a fast X-ray transient
  49. GRB 260822A: LCO optical upper limits
  50. The EP-WXT trigger 01709287395 is likely a flaring star
  51. GRB260822B: Fermi GBM Final Localization
  52. GRB 260822A: GROWTH-India Telescope Upper Limits
  53. GRB 260822A: GOTO optical upper limit
  54. GRB 260822A: SVOM detection of a short burst
  55. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  56. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  57. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 260818B: VLA radio observations
  59. GRB 260818B: SVOM/C-GFT optical upper limit
  60. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  61. The EP-WXT trigger 01709286204 is likely a flaring star
  62. GRB 260820A: Insight-HXMT/HE detection
  63. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 260818B: SVOM/GRM observation
  65. EP detected a brightening of LMXB 1ES 1735-26.9
  66. GRB260820A: Fermi GBM Final Real-Time Localization
  67. GRB 260818B: Insight-HXMT detection
  68. GRB 260818B: EP-FXT follow-up observation
  69. GRB 260818A: J-band observations with WINTER
  70. GRB 260818B: SVOM/ECLAIRs refined analysis
  71. GRB 260818A: SVOM/ECLAIRs refined analysis
  72. GRB 260818B: NOT optical upper limits
  73. GRB 260810A: SVOM/GRM observation
  74. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. GRB260818A: EP-FXT follow-up observation
  76. GRB 260818B: LCO optical upper limits
  77. GRB 260818B: SVOM detection of a short burst
  78. SVOM trigger sb26081806 is not a GRB
  79. EP260806a: SAO RAS multicolor optical observations
  80. GRB 260818A: LCO optical upper limits
  81. EP260812a: AbAO optical upper limit
  82. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. GRB 260810A: Insight-HXMT/HE detection
  84. GRB 260818A: SVOM possible detection of a long and faint GRB
  85. EP260806a: SVOM/ECLAIRs detection through targeted search
  86. EP260806a: NUTTELA-TAO optical observations
  87. The EP-WXT trigger 01709281429 is likely a flaring star
  88. EP260812a: AZT-22 optical upper limit
  89. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  90. EP260806a: WFST optical observations
  91. The EP-WXT trigger 01709280562 is likely a flaring star
  92. EP260812b: Optical upper limit with Kinder
  93. The EP-WXT trigger 01709279838 is likely a flaring star
  94. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  95. GRB 260808B: Liverpool Telescope further optical observations
  96. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  97. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  98. GRB 260813A: Fermi GBM Final Real-time Localization
  99. EP260812a: NOT and Liverpool Telescope upper limits:
  100. EP260812b: Liverpool Telescope observations

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