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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"

27823 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. GRB 260807A: EP-FXT follow-up observations
  6. IceCube Alert 260825A: Global MASTER-Net observations report
  7. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  9. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  10. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  11. EP260822a: EP-FXT non-detection and upper limit
  12. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  13. EP260822a: Einstein Probe detection of a fast X-ray transient
  14. GRB 260822A: LCO optical upper limits
  15. GRB 260822A: GROWTH-India Telescope Upper Limits
  16. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  17. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  18. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  19. GRB 260818B: VLA radio observations
  20. GRB 260818B: SVOM/C-GFT optical upper limit
  21. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  22. IceCube Alert 260821A: Global MASTER-Net observations report
  23. GRB 260820A: Insight-HXMT/HE detection
  24. EP detected a brightening of LMXB 1ES 1735-26.9
  25. GRB 260818A: J-band observations with WINTER
  26. GRB 260818A: SVOM/ECLAIRs refined analysis
  27. GRB 260818B: NOT optical upper limits
  28. GRB 260810A: SVOM/GRM observation
  29. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  30. GRB 260818B: LCO optical upper limits
  31. GRB 260818B: SVOM detection of a short burst
  32. EP260806a: SAO RAS multicolor optical observations
  33. GRB 260818A: LCO optical upper limits
  34. EP260812a: AbAO optical upper limit
  35. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  36. GRB 260810A: Insight-HXMT/HE detection
  37. GRB 260818A: SVOM possible detection of a long and faint GRB
  38. EP260806a: NUTTELA-TAO optical observations
  39. The EP-WXT trigger 01709281429 is likely a flaring star
  40. EP260812a: AZT-22 optical upper limit
  41. EP260806a: WFST optical observations
  42. EP260812b: Optical upper limit with Kinder
  43. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  44. GRB 260808B: Liverpool Telescope further optical observations
  45. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  46. EP260812a: NOT and Liverpool Telescope upper limits:
  47. EP260812b: Liverpool Telescope observations
  48. EP260812b: GOTO detection of the optical counterpart
  49. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  50. EP260812a: SVOM/C-GFT optical upper limit
  51. EP260812b: COLIBRÍ optical observations
  52. EP260812b: SVOM/VT optical observation
  53. GRB 260808A: SVOM/GRM observation
  54. EP260812b: Einstein Probe detection of an X-ray transient
  55. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  56. Fermi GBM Sub-Threshold Detection of GRB 260809A
  57. GRB 260810A: Glowbug gamma-ray detection
  58. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  59. GRB 260810A: AstroSat CZTI detection of a long burst
  60. EP260812a: Einstein Probe detection of an X-ray transient
  61. GRB 260809A: SAO RAS optical observations
  62. GRB 260808B: SAO RAS optical observations
  63. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  64. EP260806a: MAO/AZT-22 optical observations
  65. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB260808B: MAO/AZT-22 optical observations
  67. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  68. GRB 260809A: J-band upper limit with WINTER
  69. GRB 260806A: Glowbug gamma-ray detection
  70. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  71. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  72. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  73. GRB 260809A: NOT optical observations
  74. GRB260809A: MAO/AZT-22 optical observations
  75. GRB260809A: OHP/T193 optical observations
  76. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  77. EP260809a: J-band upper limit with WINTER
  78. GRB 260808B: J-band upper limit with WINTER
  79. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  80. GRB 260809A: SVOM detection of a faint burst
  81. GRB 260808B: Liverpool Telescope optical observations
  82. GRB 260808B: NOT optical observations
  83. GRB 260808B: LCO optical observations
  84. GRB 260808A: NuSTAR detection of prompt emission
  85. EP260809a: COLIBRÍ optical observations
  86. EP260809a: LCO optical observation
  87. EP260809a: OHP/T193 optical observations
  88. GRB260808B: OHP/T193 optical observations
  89. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  90. EP260809a: Einstein Probe detection of an X-ray transient
  91. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  92. GRB 260808B: SVOM/VT optical candidate from VHF data
  93. GRB 260808B: SVOM detection of a faint burst
  94. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  95. Fermi GRB 260808A: Global MASTER-Net observations report
  96. IceCube Alert 260807A: Global MASTER-Net observations report
  97. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  98. GRB 260807A: SVOM possible detection of a faint burst
  99. EP260806a: COLIBRÍ optical observations
  100. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations

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