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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"

27824 results found.

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

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