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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"

45136 results found.

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

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