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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"

26303 results found.

  1. GRB 260829A: Fermi GBM Detection
  2. GRB 260825A: AstroSat CZTI detection
  3. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  4. IceCube-260827A: 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. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 260818B: Further EP-FXT observation
  8. GRB 260818B: VLT optical and nIR observations
  9. GRB 260818B: TNG NIR observations
  10. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  11. GRB 260818B: 6 GHz VLA observations
  12. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  13. GRB 260808B: SAO RAS observations of the optical rebrightening
  14. EP Alert 260820.31: Global MASTER-Net observations report
  15. GRB 260807A: EP-FXT follow-up observations
  16. GRB 260822A: SVOM/ECLAIRs refined analysis
  17. GRB 260809A: SVOM/ECLAIRs refined analysis
  18. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  19. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  20. GRB 260822A: EP/FXT follow-up observations
  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. The EP-WXT trigger 01709287395 is likely a flaring star
  28. GRB 260822A: GROWTH-India Telescope Upper Limits
  29. GRB 260822A: SVOM detection of a short burst
  30. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  31. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  32. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 260818B: SVOM/C-GFT optical upper limit
  34. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  35. The EP-WXT trigger 01709286204 is likely a flaring star
  36. GRB 260818B: SVOM/GRM observation
  37. EP detected a brightening of LMXB 1ES 1735-26.9
  38. GRB 260818B: EP-FXT follow-up observation
  39. GRB 260818A: J-band observations with WINTER
  40. GRB 260818B: SVOM/ECLAIRs refined analysis
  41. GRB 260818A: SVOM/ECLAIRs refined analysis
  42. GRB 260818B: NOT optical upper limits
  43. GRB 260810A: SVOM/GRM observation
  44. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  45. GRB260818A: EP-FXT follow-up observation
  46. GRB 260818B: LCO optical upper limits
  47. GRB 260818B: SVOM detection of a short burst
  48. EP260806a: SAO RAS multicolor optical observations
  49. GRB 260818A: LCO optical upper limits
  50. EP260812a: AbAO optical upper limit
  51. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. GRB 260818A: SVOM possible detection of a long and faint GRB
  53. EP260806a: SVOM/ECLAIRs detection through targeted search
  54. EP260806a: NUTTELA-TAO optical observations
  55. The EP-WXT trigger 01709281429 is likely a flaring star
  56. EP260812a: AZT-22 optical upper limit
  57. EP260806a: WFST optical observations
  58. The EP-WXT trigger 01709280562 is likely a flaring star
  59. EP260812b: Optical upper limit with Kinder
  60. The EP-WXT trigger 01709279838 is likely a flaring star
  61. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  62. GRB 260808B: Liverpool Telescope further optical observations
  63. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  64. EP260812a: NOT and Liverpool Telescope upper limits:
  65. EP260812b: Liverpool Telescope observations
  66. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  67. EP260812a: SVOM/C-GFT optical upper limit
  68. EP260812b: COLIBRÍ optical observations
  69. EP260812b: SVOM/VT optical observation
  70. GRB 260808A: SVOM/GRM observation
  71. EP260812b: Einstein Probe detection of an X-ray transient
  72. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  73. GRB 260810A: Glowbug gamma-ray detection
  74. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  75. GRB 260810A: AstroSat CZTI detection of a long burst
  76. EP260812a: Einstein Probe detection of an X-ray transient
  77. GRB 260809A: SAO RAS optical observations
  78. GRB 260808B: SAO RAS optical observations
  79. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  80. GRB 260808A: GECAM-B observation
  81. GRB 260807A: SVOM/ECLAIRs refined analysis
  82. EP260806a: MAO/AZT-22 optical observations
  83. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB260808B: MAO/AZT-22 optical observations
  85. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  86. GRB 260809A: J-band upper limit with WINTER
  87. GRB 260806A: Glowbug gamma-ray detection
  88. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  89. The EP-WXT trigger 01709278015 is likely a flaring star
  90. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  91. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  92. GRB 260809A: NOT optical observations
  93. GRB260809A: MAO/AZT-22 optical observations
  94. GRB260809A: OHP/T193 optical observations
  95. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  96. EP260809a: J-band upper limit with WINTER
  97. GRB 260808B: J-band upper limit with WINTER
  98. GRB 260808B: SVOM/ECLAIRs refined analysis
  99. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  100. GRB 260809A: SVOM detection of a faint burst

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