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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"

27825 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. GRB 260818B: 6 GHz VLA observations
  6. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  7. GRB 260808B: SAO RAS observations of the optical rebrightening
  8. EP260822a: Global MASTER-Net observations report
  9. EP Alert 260820.31: Global MASTER-Net observations report
  10. GRB 260807A: EP-FXT follow-up observations
  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 260822A: PRIME near-infrared upper limits from multiple epochs
  14. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  15. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  16. EP260822a: EP-FXT non-detection and upper limit
  17. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  18. EP260822a: Einstein Probe detection of a fast X-ray transient
  19. GRB 260822A: LCO optical upper limits
  20. GRB 260822A: GROWTH-India Telescope Upper Limits
  21. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  22. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  23. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 260818B: VLA radio observations
  25. GRB 260818B: SVOM/C-GFT optical upper limit
  26. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  27. IceCube Alert 260821A: Global MASTER-Net observations report
  28. GRB 260820A: Insight-HXMT/HE detection
  29. EP detected a brightening of LMXB 1ES 1735-26.9
  30. GRB 260818A: J-band observations with WINTER
  31. GRB 260818A: SVOM/ECLAIRs refined analysis
  32. GRB 260818B: NOT optical upper limits
  33. GRB 260810A: SVOM/GRM observation
  34. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  35. GRB 260818B: LCO optical upper limits
  36. GRB 260818B: SVOM detection of a short burst
  37. EP260806a: SAO RAS multicolor optical observations
  38. GRB 260818A: LCO optical upper limits
  39. EP260812a: AbAO optical upper limit
  40. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  41. GRB 260810A: Insight-HXMT/HE detection
  42. GRB 260818A: SVOM possible detection of a long and faint GRB
  43. EP260806a: NUTTELA-TAO optical observations
  44. The EP-WXT trigger 01709281429 is likely a flaring star
  45. EP260812a: AZT-22 optical upper limit
  46. EP260806a: WFST optical observations
  47. EP260812b: Optical upper limit with Kinder
  48. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  49. GRB 260808B: Liverpool Telescope further optical observations
  50. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  51. EP260812a: NOT and Liverpool Telescope upper limits:
  52. EP260812b: Liverpool Telescope observations
  53. EP260812b: GOTO detection of the optical counterpart
  54. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  55. EP260812a: SVOM/C-GFT optical upper limit
  56. EP260812b: COLIBRÍ optical observations
  57. EP260812b: SVOM/VT optical observation
  58. GRB 260808A: SVOM/GRM observation
  59. EP260812b: Einstein Probe detection of an X-ray transient
  60. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  61. Fermi GBM Sub-Threshold Detection of GRB 260809A
  62. GRB 260810A: Glowbug gamma-ray detection
  63. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  64. GRB 260810A: AstroSat CZTI detection of a long burst
  65. EP260812a: Einstein Probe detection of an X-ray transient
  66. GRB 260809A: SAO RAS optical observations
  67. GRB 260808B: SAO RAS optical observations
  68. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  69. EP260806a: MAO/AZT-22 optical observations
  70. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  71. GRB260808B: MAO/AZT-22 optical observations
  72. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  73. GRB 260809A: J-band upper limit with WINTER
  74. GRB 260806A: Glowbug gamma-ray detection
  75. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  76. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  77. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  78. GRB 260809A: NOT optical observations
  79. GRB260809A: MAO/AZT-22 optical observations
  80. GRB260809A: OHP/T193 optical observations
  81. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  82. EP260809a: J-band upper limit with WINTER
  83. GRB 260808B: J-band upper limit with WINTER
  84. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  85. GRB 260809A: SVOM detection of a faint burst
  86. GRB 260808B: Liverpool Telescope optical observations
  87. GRB 260808B: NOT optical observations
  88. GRB 260808B: LCO optical observations
  89. GRB 260808A: NuSTAR detection of prompt emission
  90. EP260809a: COLIBRÍ optical observations
  91. EP260809a: LCO optical observation
  92. EP260809a: OHP/T193 optical observations
  93. GRB260808B: OHP/T193 optical observations
  94. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  95. EP260809a: Einstein Probe detection of an X-ray transient
  96. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  97. GRB 260808B: SVOM/VT optical candidate from VHF data
  98. GRB 260808B: SVOM detection of a faint burst
  99. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  100. Fermi GRB 260808A: Global MASTER-Net observations report

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