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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"

41695 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 260818B: 6 GHz VLA observations
  8. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  9. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  10. GRB 260808B: SAO RAS observations of the optical rebrightening
  11. EP260822a: Global MASTER-Net observations report
  12. EP Alert 260820.31: Global MASTER-Net observations report
  13. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  14. GRB 260807A: EP-FXT follow-up observations
  15. GRB 260822A: SVOM/ECLAIRs refined analysis
  16. GRB 260809A: SVOM/ECLAIRs refined analysis
  17. GRB 260822A: SVOM/VT optical upper limits
  18. IceCube Alert 260825A: Global MASTER-Net observations report
  19. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  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. GRB 260822A: LCO optical upper limits
  31. The EP-WXT trigger 01709287395 is likely a flaring star
  32. GRB260822B: Fermi GBM Final Localization
  33. GRB 260822A: GROWTH-India Telescope Upper Limits
  34. GRB 260822A: GOTO optical upper limit
  35. GRB 260822A: SVOM detection of a short burst
  36. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  37. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  38. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 260818B: VLA radio observations
  40. GRB 260818B: SVOM/C-GFT optical upper limit
  41. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  42. IceCube Alert 260821A: Global MASTER-Net observations report
  43. The EP-WXT trigger 01709286204 is likely a flaring star
  44. GRB 260820A: Insight-HXMT/HE detection
  45. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 260818B: SVOM/GRM observation
  47. EP detected a brightening of LMXB 1ES 1735-26.9
  48. GRB 260818B: Insight-HXMT detection
  49. GRB 260818B: EP-FXT follow-up observation
  50. GRB 260818A: J-band observations with WINTER
  51. GRB 260818B: SVOM/ECLAIRs refined analysis
  52. GRB 260818A: SVOM/ECLAIRs refined analysis
  53. GRB 260818B: NOT optical upper limits
  54. GRB 260810A: SVOM/GRM observation
  55. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  56. GRB260818A: EP-FXT follow-up observation
  57. GRB 260818B: LCO optical upper limits
  58. GRB 260818B: SVOM detection of a short burst
  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. EP260812a: NOT and Liverpool Telescope upper limits:
  78. EP260812b: Liverpool Telescope observations
  79. EP260812b: GOTO detection of the optical counterpart
  80. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  81. EP260812a: SVOM/C-GFT optical upper limit
  82. EP260812b: COLIBRÍ optical observations
  83. EP260812b: SVOM/VT optical observation
  84. GRB 260808A: SVOM/GRM observation
  85. EP260812b: Einstein Probe detection of an X-ray transient
  86. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  87. Fermi GBM Sub-Threshold Detection of GRB 260809A
  88. GRB 260810A: Glowbug gamma-ray detection
  89. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  90. GRB 260810A: AstroSat CZTI detection of a long burst
  91. EP260812a: Einstein Probe detection of an X-ray transient
  92. GRB 260809A: SAO RAS optical observations
  93. GRB 260808B: SAO RAS optical observations
  94. GRB 260808B: SVOM/VT optical re-brightening at day 3
  95. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  96. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  97. GRB 260808A: GECAM-B observation
  98. GRB 260807A: SVOM/ECLAIRs refined analysis
  99. EP260806a: MAO/AZT-22 optical observations
  100. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube

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