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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"

45629 results found.

  1. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  2. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  3. GRB 260808B: SAO RAS observations of the optical rebrightening
  4. EP260822a: Global MASTER-Net observations report
  5. EP Alert 260820.31: Global MASTER-Net observations report
  6. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  7. GRB 260807A: EP-FXT follow-up observations
  8. GRB 260822A: SVOM/ECLAIRs refined analysis
  9. GRB 260809A: SVOM/ECLAIRs refined analysis
  10. GRB 260822A: SVOM/VT optical upper limits
  11. IceCube Alert 260825A: Global MASTER-Net observations report
  12. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 260825A: Fermi GBM Final Real-time Localization
  14. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  15. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  16. GRB 260822A: EP/FXT follow-up observations
  17. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  18. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  19. EP260822a: EP-FXT non-detection and upper limit
  20. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  21. GRB 260822A: GOTO optical counterpart detection
  22. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  23. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  24. EP260822a: Einstein Probe detection of a fast X-ray transient
  25. GRB 260822A: LCO optical upper limits
  26. The EP-WXT trigger 01709287395 is likely a flaring star
  27. GRB260822B: Fermi GBM Final Localization
  28. GRB 260822A: GROWTH-India Telescope Upper Limits
  29. GRB 260822A: GOTO optical upper limit
  30. GRB 260822A: SVOM detection of a short burst
  31. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  32. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  33. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 260818B: VLA radio observations
  35. GRB 260818B: SVOM/C-GFT optical upper limit
  36. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  37. IceCube Alert 260821A: Global MASTER-Net observations report
  38. The EP-WXT trigger 01709286204 is likely a flaring star
  39. GRB 260820A: Insight-HXMT/HE detection
  40. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 260818B: SVOM/GRM observation
  42. EP detected a brightening of LMXB 1ES 1735-26.9
  43. GRB260820A: Fermi GBM Final Real-Time Localization
  44. GRB 260818B: Insight-HXMT detection
  45. GRB 260818B: EP-FXT follow-up observation
  46. GRB 260818A: J-band observations with WINTER
  47. GRB 260818B: SVOM/ECLAIRs refined analysis
  48. GRB 260818A: SVOM/ECLAIRs refined analysis
  49. GRB 260818B: NOT optical upper limits
  50. GRB 260810A: SVOM/GRM observation
  51. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. GRB260818A: EP-FXT follow-up observation
  53. GRB 260818B: LCO optical upper limits
  54. GRB 260818B: SVOM detection of a short burst
  55. SVOM trigger sb26081806 is not a GRB
  56. EP260806a: SAO RAS multicolor optical observations
  57. GRB 260818A: LCO optical upper limits
  58. EP260812a: AbAO optical upper limit
  59. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  60. GRB 260810A: Insight-HXMT/HE detection
  61. GRB 260818A: SVOM possible detection of a long and faint GRB
  62. EP260806a: SVOM/ECLAIRs detection through targeted search
  63. EP260806a: NUTTELA-TAO optical observations
  64. The EP-WXT trigger 01709281429 is likely a flaring star
  65. EP260812a: AZT-22 optical upper limit
  66. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  67. EP260806a: WFST optical observations
  68. The EP-WXT trigger 01709280562 is likely a flaring star
  69. EP260812b: Optical upper limit with Kinder
  70. The EP-WXT trigger 01709279838 is likely a flaring star
  71. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  72. GRB 260808B: Liverpool Telescope further optical observations
  73. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  74. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  75. GRB 260813A: Fermi GBM Final Real-time Localization
  76. EP260812a: NOT and Liverpool Telescope upper limits:
  77. EP260812b: Liverpool Telescope observations
  78. EP260812b: GOTO detection of the optical counterpart
  79. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  80. EP260812a: SVOM/C-GFT optical upper limit
  81. EP260812b: COLIBRÍ optical observations
  82. EP260812b: SVOM/VT optical observation
  83. GRB 260808A: SVOM/GRM observation
  84. EP260812b: Einstein Probe detection of an X-ray transient
  85. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  86. Fermi GBM Sub-Threshold Detection of GRB 260809A
  87. GRB 260810A: Glowbug gamma-ray detection
  88. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  89. GRB 260810A: AstroSat CZTI detection of a long burst
  90. EP260812a: Einstein Probe detection of an X-ray transient
  91. GRB 260809A: SAO RAS optical observations
  92. GRB 260808B: SAO RAS optical observations
  93. GRB 260808B: SVOM/VT optical re-brightening at day 3
  94. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  95. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  96. GRB 260808A: GECAM-B observation
  97. GRB 260807A: SVOM/ECLAIRs refined analysis
  98. EP260806a: MAO/AZT-22 optical observations
  99. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB260808B: MAO/AZT-22 optical observations

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