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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"
  1. GRB 260818B: TNG NIR observations
  2. MAXI GRB260827.40: Global MASTER-Net observations report
  3. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  4. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  5. GRB 260827A: Fermi GBM Final Real-time Localization
  6. GRB 260818B: 6 GHz VLA observations
  7. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  8. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  9. GRB 260808B: SAO RAS observations of the optical rebrightening
  10. EP260822a: Global MASTER-Net observations report
  11. EP Alert 260820.31: Global MASTER-Net observations report
  12. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  13. GRB 260807A: EP-FXT follow-up observations
  14. GRB 260822A: SVOM/ECLAIRs refined analysis
  15. GRB 260809A: SVOM/ECLAIRs refined analysis
  16. GRB 260822A: SVOM/VT optical upper limits
  17. IceCube Alert 260825A: Global MASTER-Net observations report
  18. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  19. GRB 260825A: Fermi GBM Final Real-time Localization
  20. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  21. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  22. GRB 260822A: EP/FXT follow-up observations
  23. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  24. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  25. EP260822a: EP-FXT non-detection and upper limit
  26. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  27. GRB 260822A: GOTO optical counterpart detection
  28. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  29. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  30. EP260822a: Einstein Probe detection of a fast X-ray transient
  31. GRB 260822A: LCO optical upper limits
  32. The EP-WXT trigger 01709287395 is likely a flaring star
  33. GRB260822B: Fermi GBM Final Localization
  34. GRB 260822A: GROWTH-India Telescope Upper Limits
  35. GRB 260822A: GOTO optical upper limit
  36. GRB 260822A: SVOM detection of a short burst
  37. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  38. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  39. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 260818B: VLA radio observations
  41. GRB 260818B: SVOM/C-GFT optical upper limit
  42. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  43. IceCube Alert 260821A: Global MASTER-Net observations report
  44. The EP-WXT trigger 01709286204 is likely a flaring star
  45. GRB 260820A: Insight-HXMT/HE detection
  46. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  47. GRB 260818B: SVOM/GRM observation
  48. EP detected a brightening of LMXB 1ES 1735-26.9
  49. GRB260820A: Fermi GBM Final Real-Time Localization
  50. GRB 260818B: Insight-HXMT detection
  51. GRB 260818B: EP-FXT follow-up observation
  52. GRB 260818A: J-band observations with WINTER
  53. GRB 260818B: SVOM/ECLAIRs refined analysis
  54. GRB 260818A: SVOM/ECLAIRs refined analysis
  55. GRB 260818B: NOT optical upper limits
  56. GRB 260810A: SVOM/GRM observation
  57. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. GRB260818A: EP-FXT follow-up observation
  59. GRB 260818B: LCO optical upper limits
  60. GRB 260818B: SVOM detection of a short burst
  61. SVOM trigger sb26081806 is not a GRB
  62. EP260806a: SAO RAS multicolor optical observations
  63. GRB 260818A: LCO optical upper limits
  64. EP260812a: AbAO optical upper limit
  65. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB 260810A: Insight-HXMT/HE detection
  67. GRB 260818A: SVOM possible detection of a long and faint GRB
  68. EP260806a: SVOM/ECLAIRs detection through targeted search
  69. EP260806a: NUTTELA-TAO optical observations
  70. The EP-WXT trigger 01709281429 is likely a flaring star
  71. EP260812a: AZT-22 optical upper limit
  72. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  73. EP260806a: WFST optical observations
  74. The EP-WXT trigger 01709280562 is likely a flaring star
  75. EP260812b: Optical upper limit with Kinder
  76. The EP-WXT trigger 01709279838 is likely a flaring star
  77. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  78. GRB 260808B: Liverpool Telescope further optical observations
  79. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  80. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  81. GRB 260813A: Fermi GBM Final Real-time Localization
  82. EP260812a: NOT and Liverpool Telescope upper limits:
  83. EP260812b: Liverpool Telescope observations
  84. EP260812b: GOTO detection of the optical counterpart
  85. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  86. EP260812a: SVOM/C-GFT optical upper limit
  87. EP260812b: COLIBRÍ optical observations
  88. EP260812b: SVOM/VT optical observation
  89. GRB 260808A: SVOM/GRM observation
  90. EP260812b: Einstein Probe detection of an X-ray transient
  91. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  92. Fermi GBM Sub-Threshold Detection of GRB 260809A
  93. GRB 260810A: Glowbug gamma-ray detection
  94. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  95. GRB 260810A: AstroSat CZTI detection of a long burst
  96. EP260812a: Einstein Probe detection of an X-ray transient
  97. GRB 260809A: SAO RAS optical observations
  98. GRB 260808B: SAO RAS optical observations
  99. GRB 260808B: SVOM/VT optical re-brightening at day 3
  100. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5

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