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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"

27836 results found.

  1. GRB 260827A: Glowbug gamma-ray detection
  2. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  3. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  4. GRB 260825A: SVOM/GRM observation of a long burst
  5. GRB 260829A: Fermi GBM Detection
  6. GRB 260825A: AstroSat CZTI detection
  7. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  8. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  10. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 260818B: Further EP-FXT observation
  12. GRB 260818B: VLT optical and nIR observations
  13. GRB 260818B: TNG NIR observations
  14. MAXI GRB260827.40: Global MASTER-Net observations report
  15. GRB 260818B: 6 GHz VLA observations
  16. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  17. GRB 260808B: SAO RAS observations of the optical rebrightening
  18. EP260822a: Global MASTER-Net observations report
  19. EP Alert 260820.31: Global MASTER-Net observations report
  20. GRB 260807A: EP-FXT follow-up observations
  21. IceCube Alert 260825A: Global MASTER-Net observations report
  22. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  24. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  25. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  26. EP260822a: EP-FXT non-detection and upper limit
  27. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  28. EP260822a: Einstein Probe detection of a fast X-ray transient
  29. GRB 260822A: LCO optical upper limits
  30. GRB 260822A: GROWTH-India Telescope Upper Limits
  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. GRB 260820A: Insight-HXMT/HE detection
  39. EP detected a brightening of LMXB 1ES 1735-26.9
  40. GRB 260818A: J-band observations with WINTER
  41. GRB 260818A: SVOM/ECLAIRs refined analysis
  42. GRB 260818B: NOT optical upper limits
  43. GRB 260810A: SVOM/GRM observation
  44. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  45. GRB 260818B: LCO optical upper limits
  46. GRB 260818B: SVOM detection of a short burst
  47. EP260806a: SAO RAS multicolor optical observations
  48. GRB 260818A: LCO optical upper limits
  49. EP260812a: AbAO optical upper limit
  50. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  51. GRB 260810A: Insight-HXMT/HE detection
  52. GRB 260818A: SVOM possible detection of a long and faint GRB
  53. EP260806a: NUTTELA-TAO optical observations
  54. The EP-WXT trigger 01709281429 is likely a flaring star
  55. EP260812a: AZT-22 optical upper limit
  56. EP260806a: WFST optical observations
  57. EP260812b: Optical upper limit with Kinder
  58. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  59. GRB 260808B: Liverpool Telescope further optical observations
  60. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  61. EP260812a: NOT and Liverpool Telescope upper limits:
  62. EP260812b: Liverpool Telescope observations
  63. EP260812b: GOTO detection of the optical counterpart
  64. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  65. EP260812a: SVOM/C-GFT optical upper limit
  66. EP260812b: COLIBRÍ optical observations
  67. EP260812b: SVOM/VT optical observation
  68. GRB 260808A: SVOM/GRM observation
  69. EP260812b: Einstein Probe detection of an X-ray transient
  70. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  71. Fermi GBM Sub-Threshold Detection of GRB 260809A
  72. GRB 260810A: Glowbug gamma-ray detection
  73. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  74. GRB 260810A: AstroSat CZTI detection of a long burst
  75. EP260812a: Einstein Probe detection of an X-ray transient
  76. GRB 260809A: SAO RAS optical observations
  77. GRB 260808B: SAO RAS optical observations
  78. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  79. EP260806a: MAO/AZT-22 optical observations
  80. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB260808B: MAO/AZT-22 optical observations
  82. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  83. GRB 260809A: J-band upper limit with WINTER
  84. GRB 260806A: Glowbug gamma-ray detection
  85. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  86. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  87. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  88. GRB 260809A: NOT optical observations
  89. GRB260809A: MAO/AZT-22 optical observations
  90. GRB260809A: OHP/T193 optical observations
  91. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  92. EP260809a: J-band upper limit with WINTER
  93. GRB 260808B: J-band upper limit with WINTER
  94. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  95. GRB 260809A: SVOM detection of a faint burst
  96. GRB 260808B: Liverpool Telescope optical observations
  97. GRB 260808B: NOT optical observations
  98. GRB 260808B: LCO optical observations
  99. GRB 260808A: NuSTAR detection of prompt emission
  100. EP260809a: COLIBRÍ optical observations

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