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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"

27830 results found.

  1. GRB 260825A: AstroSat CZTI detection
  2. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  3. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  4. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  5. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 260818B: Further EP-FXT observation
  7. GRB 260818B: VLT optical and nIR observations
  8. GRB 260818B: TNG NIR observations
  9. MAXI GRB260827.40: Global MASTER-Net observations report
  10. GRB 260818B: 6 GHz VLA observations
  11. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  12. GRB 260808B: SAO RAS observations of the optical rebrightening
  13. EP260822a: Global MASTER-Net observations report
  14. EP Alert 260820.31: Global MASTER-Net observations report
  15. GRB 260807A: EP-FXT follow-up observations
  16. IceCube Alert 260825A: Global MASTER-Net observations report
  17. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  19. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  20. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  21. EP260822a: EP-FXT non-detection and upper limit
  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. GRB 260822A: GROWTH-India Telescope Upper Limits
  26. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  27. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  28. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 260818B: VLA radio observations
  30. GRB 260818B: SVOM/C-GFT optical upper limit
  31. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  32. IceCube Alert 260821A: Global MASTER-Net observations report
  33. GRB 260820A: Insight-HXMT/HE detection
  34. EP detected a brightening of LMXB 1ES 1735-26.9
  35. GRB 260818A: J-band observations with WINTER
  36. GRB 260818A: SVOM/ECLAIRs refined analysis
  37. GRB 260818B: NOT optical upper limits
  38. GRB 260810A: SVOM/GRM observation
  39. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  40. GRB 260818B: LCO optical upper limits
  41. GRB 260818B: SVOM detection of a short burst
  42. EP260806a: SAO RAS multicolor optical observations
  43. GRB 260818A: LCO optical upper limits
  44. EP260812a: AbAO optical upper limit
  45. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  46. GRB 260810A: Insight-HXMT/HE detection
  47. GRB 260818A: SVOM possible detection of a long and faint GRB
  48. EP260806a: NUTTELA-TAO optical observations
  49. The EP-WXT trigger 01709281429 is likely a flaring star
  50. EP260812a: AZT-22 optical upper limit
  51. EP260806a: WFST optical observations
  52. EP260812b: Optical upper limit with Kinder
  53. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  54. GRB 260808B: Liverpool Telescope further optical observations
  55. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  56. EP260812a: NOT and Liverpool Telescope upper limits:
  57. EP260812b: Liverpool Telescope observations
  58. EP260812b: GOTO detection of the optical counterpart
  59. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  60. EP260812a: SVOM/C-GFT optical upper limit
  61. EP260812b: COLIBRÍ optical observations
  62. EP260812b: SVOM/VT optical observation
  63. GRB 260808A: SVOM/GRM observation
  64. EP260812b: Einstein Probe detection of an X-ray transient
  65. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  66. Fermi GBM Sub-Threshold Detection of GRB 260809A
  67. GRB 260810A: Glowbug gamma-ray detection
  68. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  69. GRB 260810A: AstroSat CZTI detection of a long burst
  70. EP260812a: Einstein Probe detection of an X-ray transient
  71. GRB 260809A: SAO RAS optical observations
  72. GRB 260808B: SAO RAS optical observations
  73. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  74. EP260806a: MAO/AZT-22 optical observations
  75. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  76. GRB260808B: MAO/AZT-22 optical observations
  77. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  78. GRB 260809A: J-band upper limit with WINTER
  79. GRB 260806A: Glowbug gamma-ray detection
  80. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  81. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  82. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  83. GRB 260809A: NOT optical observations
  84. GRB260809A: MAO/AZT-22 optical observations
  85. GRB260809A: OHP/T193 optical observations
  86. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  87. EP260809a: J-band upper limit with WINTER
  88. GRB 260808B: J-band upper limit with WINTER
  89. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  90. GRB 260809A: SVOM detection of a faint burst
  91. GRB 260808B: Liverpool Telescope optical observations
  92. GRB 260808B: NOT optical observations
  93. GRB 260808B: LCO optical observations
  94. GRB 260808A: NuSTAR detection of prompt emission
  95. EP260809a: COLIBRÍ optical observations
  96. EP260809a: LCO optical observation
  97. EP260809a: OHP/T193 optical observations
  98. GRB260808B: OHP/T193 optical observations
  99. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  100. EP260809a: Einstein Probe detection of an X-ray transient

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