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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"

42451 results found.

  1. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  2. GRB 260808B: SAO RAS observations of the optical rebrightening
  3. EP260822a: Global MASTER-Net observations report
  4. EP Alert 260820.31: Global MASTER-Net observations report
  5. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  6. GRB 260807A: EP-FXT follow-up observations
  7. GRB 260822A: SVOM/ECLAIRs refined analysis
  8. GRB 260809A: SVOM/ECLAIRs refined analysis
  9. GRB 260822A: SVOM/VT optical upper limits
  10. IceCube Alert 260825A: Global MASTER-Net observations report
  11. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  12. GRB 260825A: Fermi GBM Final Real-time Localization
  13. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  15. GRB 260822A: EP/FXT follow-up observations
  16. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  17. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  18. EP260822a: EP-FXT non-detection and upper limit
  19. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  20. GRB 260822A: GOTO optical counterpart detection
  21. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  22. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  23. EP260822a: Einstein Probe detection of a fast X-ray transient
  24. GRB 260822A: LCO optical upper limits
  25. The EP-WXT trigger 01709287395 is likely a flaring star
  26. GRB260822B: Fermi GBM Final Localization
  27. GRB 260822A: GROWTH-India Telescope Upper Limits
  28. GRB 260822A: GOTO optical upper limit
  29. GRB 260822A: SVOM detection of a short burst
  30. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  31. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  32. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 260818B: VLA radio observations
  34. GRB 260818B: SVOM/C-GFT optical upper limit
  35. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  36. IceCube Alert 260821A: Global MASTER-Net observations report
  37. The EP-WXT trigger 01709286204 is likely a flaring star
  38. GRB 260820A: Insight-HXMT/HE detection
  39. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 260818B: SVOM/GRM observation
  41. EP detected a brightening of LMXB 1ES 1735-26.9
  42. GRB260820A: Fermi GBM Final Real-Time Localization
  43. GRB 260818B: Insight-HXMT detection
  44. GRB 260818B: EP-FXT follow-up observation
  45. GRB 260818A: J-band observations with WINTER
  46. GRB 260818B: SVOM/ECLAIRs refined analysis
  47. GRB 260818A: SVOM/ECLAIRs refined analysis
  48. GRB 260818B: NOT optical upper limits
  49. GRB 260810A: SVOM/GRM observation
  50. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  51. GRB260818A: EP-FXT follow-up observation
  52. GRB 260818B: LCO optical upper limits
  53. GRB 260818B: SVOM detection of a short burst
  54. EP260806a: SAO RAS multicolor optical observations
  55. GRB 260818A: LCO optical upper limits
  56. EP260812a: AbAO optical upper limit
  57. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. GRB 260810A: Insight-HXMT/HE detection
  59. GRB 260818A: SVOM possible detection of a long and faint GRB
  60. EP260806a: SVOM/ECLAIRs detection through targeted search
  61. EP260806a: NUTTELA-TAO optical observations
  62. The EP-WXT trigger 01709281429 is likely a flaring star
  63. EP260812a: AZT-22 optical upper limit
  64. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  65. EP260806a: WFST optical observations
  66. The EP-WXT trigger 01709280562 is likely a flaring star
  67. EP260812b: Optical upper limit with Kinder
  68. The EP-WXT trigger 01709279838 is likely a flaring star
  69. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  70. GRB 260808B: Liverpool Telescope further optical observations
  71. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  72. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  73. GRB 260813A: Fermi GBM Final Real-time Localization
  74. EP260812a: NOT and Liverpool Telescope upper limits:
  75. EP260812b: Liverpool Telescope observations
  76. EP260812b: GOTO detection of the optical counterpart
  77. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  78. EP260812a: SVOM/C-GFT optical upper limit
  79. EP260812b: COLIBRÍ optical observations
  80. EP260812b: SVOM/VT optical observation
  81. GRB 260808A: SVOM/GRM observation
  82. EP260812b: Einstein Probe detection of an X-ray transient
  83. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  84. Fermi GBM Sub-Threshold Detection of GRB 260809A
  85. GRB 260810A: Glowbug gamma-ray detection
  86. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  87. GRB 260810A: AstroSat CZTI detection of a long burst
  88. EP260812a: Einstein Probe detection of an X-ray transient
  89. GRB 260809A: SAO RAS optical observations
  90. GRB 260808B: SAO RAS optical observations
  91. GRB 260808B: SVOM/VT optical re-brightening at day 3
  92. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  93. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  94. GRB 260808A: GECAM-B observation
  95. GRB 260807A: SVOM/ECLAIRs refined analysis
  96. EP260806a: MAO/AZT-22 optical observations
  97. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB260808B: MAO/AZT-22 optical observations
  99. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  100. GRB 260809A: J-band upper limit with WINTER

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