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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. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  2. GRB 260827A: Fermi GBM Final Real-time Localization
  3. GRB 260818B: 6 GHz VLA observations
  4. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  5. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  6. GRB 260808B: SAO RAS observations of the optical rebrightening
  7. EP260822a: Global MASTER-Net observations report
  8. EP Alert 260820.31: Global MASTER-Net observations report
  9. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  10. GRB 260807A: EP-FXT follow-up observations
  11. GRB 260822A: SVOM/ECLAIRs refined analysis
  12. GRB 260809A: SVOM/ECLAIRs refined analysis
  13. GRB 260822A: SVOM/VT optical upper limits
  14. IceCube Alert 260825A: Global MASTER-Net observations report
  15. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 260825A: Fermi GBM Final Real-time Localization
  17. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  19. GRB 260822A: EP/FXT follow-up observations
  20. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  21. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  22. EP260822a: EP-FXT non-detection and upper limit
  23. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  24. GRB 260822A: GOTO optical counterpart detection
  25. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  26. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  27. EP260822a: Einstein Probe detection of a fast X-ray transient
  28. GRB 260822A: LCO optical upper limits
  29. The EP-WXT trigger 01709287395 is likely a flaring star
  30. GRB260822B: Fermi GBM Final Localization
  31. GRB 260822A: GROWTH-India Telescope Upper Limits
  32. GRB 260822A: GOTO optical upper limit
  33. GRB 260822A: SVOM detection of a short burst
  34. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  35. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  36. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 260818B: VLA radio observations
  38. GRB 260818B: SVOM/C-GFT optical upper limit
  39. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  40. IceCube Alert 260821A: Global MASTER-Net observations report
  41. The EP-WXT trigger 01709286204 is likely a flaring star
  42. GRB 260820A: Insight-HXMT/HE detection
  43. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  44. GRB 260818B: SVOM/GRM observation
  45. EP detected a brightening of LMXB 1ES 1735-26.9
  46. GRB260820A: Fermi GBM Final Real-Time Localization
  47. GRB 260818B: Insight-HXMT detection
  48. GRB 260818B: EP-FXT follow-up observation
  49. GRB 260818A: J-band observations with WINTER
  50. GRB 260818B: SVOM/ECLAIRs refined analysis
  51. GRB 260818A: SVOM/ECLAIRs refined analysis
  52. GRB 260818B: NOT optical upper limits
  53. GRB 260810A: SVOM/GRM observation
  54. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  55. GRB260818A: EP-FXT follow-up observation
  56. GRB 260818B: LCO optical upper limits
  57. GRB 260818B: SVOM detection of a short burst
  58. SVOM trigger sb26081806 is not a GRB
  59. EP260806a: SAO RAS multicolor optical observations
  60. GRB 260818A: LCO optical upper limits
  61. EP260812a: AbAO optical upper limit
  62. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  63. GRB 260810A: Insight-HXMT/HE detection
  64. GRB 260818A: SVOM possible detection of a long and faint GRB
  65. EP260806a: SVOM/ECLAIRs detection through targeted search
  66. EP260806a: NUTTELA-TAO optical observations
  67. The EP-WXT trigger 01709281429 is likely a flaring star
  68. EP260812a: AZT-22 optical upper limit
  69. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  70. EP260806a: WFST optical observations
  71. The EP-WXT trigger 01709280562 is likely a flaring star
  72. EP260812b: Optical upper limit with Kinder
  73. The EP-WXT trigger 01709279838 is likely a flaring star
  74. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  75. GRB 260808B: Liverpool Telescope further optical observations
  76. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  77. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  78. GRB 260813A: Fermi GBM Final Real-time Localization
  79. EP260812a: NOT and Liverpool Telescope upper limits:
  80. EP260812b: Liverpool Telescope observations
  81. EP260812b: GOTO detection of the optical counterpart
  82. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  83. EP260812a: SVOM/C-GFT optical upper limit
  84. EP260812b: COLIBRÍ optical observations
  85. EP260812b: SVOM/VT optical observation
  86. GRB 260808A: SVOM/GRM observation
  87. EP260812b: Einstein Probe detection of an X-ray transient
  88. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  89. Fermi GBM Sub-Threshold Detection of GRB 260809A
  90. GRB 260810A: Glowbug gamma-ray detection
  91. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  92. GRB 260810A: AstroSat CZTI detection of a long burst
  93. EP260812a: Einstein Probe detection of an X-ray transient
  94. GRB 260809A: SAO RAS optical observations
  95. GRB 260808B: SAO RAS optical observations
  96. GRB 260808B: SVOM/VT optical re-brightening at day 3
  97. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  98. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 260808A: GECAM-B observation
  100. GRB 260807A: SVOM/ECLAIRs refined analysis

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