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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"

45423 results found.

  1. GRB 260825A: AstroSat CZTI detection
  2. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  3. GRB 260829A: Fermi GBM Final Real-time Localization
  4. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  5. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  6. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  7. Fermi GBM trigger 809666623/260829141 is not a GRB
  8. GRB 260818B: Further EP-FXT observation
  9. GRB 260818B: VLT optical and nIR observations
  10. GRB 260818B: TNG NIR observations
  11. MAXI GRB260827.40: Global MASTER-Net observations report
  12. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  13. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  14. GRB 260827A: Fermi GBM Final Real-time Localization
  15. GRB 260818B: 6 GHz VLA observations
  16. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  17. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  18. GRB 260808B: SAO RAS observations of the optical rebrightening
  19. EP260822a: Global MASTER-Net observations report
  20. EP Alert 260820.31: Global MASTER-Net observations report
  21. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  22. GRB 260807A: EP-FXT follow-up observations
  23. GRB 260822A: SVOM/ECLAIRs refined analysis
  24. GRB 260809A: SVOM/ECLAIRs refined analysis
  25. GRB 260822A: SVOM/VT optical upper limits
  26. IceCube Alert 260825A: Global MASTER-Net observations report
  27. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 260825A: Fermi GBM Final Real-time Localization
  29. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  31. GRB 260822A: EP/FXT follow-up observations
  32. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  33. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  34. EP260822a: EP-FXT non-detection and upper limit
  35. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  36. GRB 260822A: GOTO optical counterpart detection
  37. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  38. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  39. EP260822a: Einstein Probe detection of a fast X-ray transient
  40. GRB 260822A: LCO optical upper limits
  41. The EP-WXT trigger 01709287395 is likely a flaring star
  42. GRB260822B: Fermi GBM Final Localization
  43. GRB 260822A: GROWTH-India Telescope Upper Limits
  44. GRB 260822A: GOTO optical upper limit
  45. GRB 260822A: SVOM detection of a short burst
  46. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  47. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  48. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  49. GRB 260818B: VLA radio observations
  50. GRB 260818B: SVOM/C-GFT optical upper limit
  51. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  52. IceCube Alert 260821A: Global MASTER-Net observations report
  53. The EP-WXT trigger 01709286204 is likely a flaring star
  54. GRB 260820A: Insight-HXMT/HE detection
  55. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  56. GRB 260818B: SVOM/GRM observation
  57. EP detected a brightening of LMXB 1ES 1735-26.9
  58. GRB260820A: Fermi GBM Final Real-Time Localization
  59. GRB 260818B: Insight-HXMT detection
  60. GRB 260818B: EP-FXT follow-up observation
  61. GRB 260818A: J-band observations with WINTER
  62. GRB 260818B: SVOM/ECLAIRs refined analysis
  63. GRB 260818A: SVOM/ECLAIRs refined analysis
  64. GRB 260818B: NOT optical upper limits
  65. GRB 260810A: SVOM/GRM observation
  66. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. GRB260818A: EP-FXT follow-up observation
  68. GRB 260818B: LCO optical upper limits
  69. GRB 260818B: SVOM detection of a short burst
  70. SVOM trigger sb26081806 is not a GRB
  71. EP260806a: SAO RAS multicolor optical observations
  72. GRB 260818A: LCO optical upper limits
  73. EP260812a: AbAO optical upper limit
  74. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. GRB 260810A: Insight-HXMT/HE detection
  76. GRB 260818A: SVOM possible detection of a long and faint GRB
  77. EP260806a: SVOM/ECLAIRs detection through targeted search
  78. EP260806a: NUTTELA-TAO optical observations
  79. The EP-WXT trigger 01709281429 is likely a flaring star
  80. EP260812a: AZT-22 optical upper limit
  81. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  82. EP260806a: WFST optical observations
  83. The EP-WXT trigger 01709280562 is likely a flaring star
  84. EP260812b: Optical upper limit with Kinder
  85. The EP-WXT trigger 01709279838 is likely a flaring star
  86. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  87. GRB 260808B: Liverpool Telescope further optical observations
  88. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  89. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  90. GRB 260813A: Fermi GBM Final Real-time Localization
  91. EP260812a: NOT and Liverpool Telescope upper limits:
  92. EP260812b: Liverpool Telescope observations
  93. EP260812b: GOTO detection of the optical counterpart
  94. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  95. EP260812a: SVOM/C-GFT optical upper limit
  96. EP260812b: COLIBRÍ optical observations
  97. EP260812b: SVOM/VT optical observation
  98. GRB 260808A: SVOM/GRM observation
  99. EP260812b: Einstein Probe detection of an X-ray transient
  100. EP trigger #01709278129 (EP260812b?): NOT optical counterpart

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