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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"

27838 results found.

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

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