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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"

27937 results found.

  1. NuSTAR 260828: a 1100s hard X-ray transient
  2. GRB 260831B: SVOM detection of a possible burst
  3. GRB 260827A: Glowbug gamma-ray detection
  4. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  5. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  6. GRB 260825A: SVOM/GRM observation of a long burst
  7. GRB 260829A: Fermi GBM Detection
  8. GRB 260825A: AstroSat CZTI detection
  9. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  10. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  11. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  12. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 260818B: Further EP-FXT observation
  14. GRB 260818B: VLT optical and nIR observations
  15. GRB 260818B: TNG NIR observations
  16. MAXI GRB260827.40: Global MASTER-Net observations report
  17. GRB 260818B: 6 GHz VLA observations
  18. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  19. GRB 260808B: SAO RAS observations of the optical rebrightening
  20. EP260822a: Global MASTER-Net observations report
  21. EP Alert 260820.31: Global MASTER-Net observations report
  22. GRB 260807A: EP-FXT follow-up observations
  23. IceCube Alert 260825A: Global MASTER-Net observations report
  24. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  25. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  26. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  27. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  28. EP260822a: EP-FXT non-detection and upper limit
  29. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  30. EP260822a: Einstein Probe detection of a fast X-ray transient
  31. GRB 260822A: LCO optical upper limits
  32. GRB 260822A: GROWTH-India Telescope Upper Limits
  33. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  34. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  35. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 260818B: VLA radio observations
  37. GRB 260818B: SVOM/C-GFT optical upper limit
  38. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  39. IceCube Alert 260821A: Global MASTER-Net observations report
  40. GRB 260820A: Insight-HXMT/HE detection
  41. EP detected a brightening of LMXB 1ES 1735-26.9
  42. GRB 260818A: J-band observations with WINTER
  43. GRB 260818A: SVOM/ECLAIRs refined analysis
  44. GRB 260818B: NOT optical upper limits
  45. GRB 260810A: SVOM/GRM observation
  46. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  47. GRB 260818B: LCO optical upper limits
  48. GRB 260818B: SVOM detection of a short burst
  49. EP260806a: SAO RAS multicolor optical observations
  50. GRB 260818A: LCO optical upper limits
  51. EP260812a: AbAO optical upper limit
  52. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  53. GRB 260810A: Insight-HXMT/HE detection
  54. GRB 260818A: SVOM possible detection of a long and faint GRB
  55. EP260806a: NUTTELA-TAO optical observations
  56. The EP-WXT trigger 01709281429 is likely a flaring star
  57. EP260812a: AZT-22 optical upper limit
  58. EP260806a: WFST optical observations
  59. EP260812b: Optical upper limit with Kinder
  60. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  61. GRB 260808B: Liverpool Telescope further optical observations
  62. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  63. EP260812a: NOT and Liverpool Telescope upper limits:
  64. EP260812b: Liverpool Telescope observations
  65. EP260812b: GOTO detection of the optical counterpart
  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. Fermi GBM Sub-Threshold Detection of GRB 260809A
  74. GRB 260810A: Glowbug gamma-ray detection
  75. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  76. GRB 260810A: AstroSat CZTI detection of a long burst
  77. EP260812a: Einstein Probe detection of an X-ray transient
  78. GRB 260809A: SAO RAS optical observations
  79. GRB 260808B: SAO RAS optical observations
  80. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  81. EP260806a: MAO/AZT-22 optical observations
  82. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB260808B: MAO/AZT-22 optical observations
  84. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  85. GRB 260809A: J-band upper limit with WINTER
  86. GRB 260806A: Glowbug gamma-ray detection
  87. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  88. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  89. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  90. GRB 260809A: NOT optical observations
  91. GRB260809A: MAO/AZT-22 optical observations
  92. GRB260809A: OHP/T193 optical observations
  93. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  94. EP260809a: J-band upper limit with WINTER
  95. GRB 260808B: J-band upper limit with WINTER
  96. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  97. GRB 260809A: SVOM detection of a faint burst
  98. GRB 260808B: Liverpool Telescope optical observations
  99. GRB 260808B: NOT optical observations
  100. GRB 260808B: LCO optical observations

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