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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"

45422 results found.

  1. GRB 260909A: VLT optical and near-infrared upper limits
  2. EP Alert 260909.53: Global MASTER-Net observations report
  3. GRB 260909A: EP-FXT follow-up observation
  4. GRB 260910A: Fermi GBM Final Real-time Localization
  5. EP260806a: NOEMA detection
  6. EP260623a: NOEMA detections
  7. GRB 260909A: SVOM/VT optical upper limits
  8. GRB 260909A: SVOM/GRM observation
  9. GRB 260909A: Mondy optical observations and afterglow candidate
  10. GRB 260909A: Xinglong 2.16m optical upper limit
  11. GRB 260909A: SVOM/C-GFT optical upper limit
  12. GRB 260909A: SVOM detection of a burst
  13. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  14. Fermi trigger No 810554827: Global MASTER-Net observations report
  15. EP Alert 260908.60: Global MASTER-Net observations report
  16. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  17. GRB 260903A: Swift ToO observations
  18. Fermi GRB 260907B: Global MASTER-Net observations report
  19. GRB 260903A: SAO RAS optical upper limit
  20. The EP-WXT trigger 01709305715 is likely a flaring star
  21. GRB 260907B: Fermi GBM Final Real-time Localization
  22. Fermi GRB 260907A: Global MASTER-Net observations report
  23. GRB 260907A: Fermi GBM Final Real-time Localization
  24. EP260903a: EP-FXT follow-up observation
  25. EP Alert 260905.11: Global MASTER-Net observations report
  26. The EP-WXT trigger 01709302592 is likely a flaring star
  27. GRB 260903A: J-band upper limit with WINTER
  28. EP Alert 260903.47: Global MASTER-Net observations report
  29. GRB 260903A: SVOM/ECLAIRs refined analysis
  30. GRB260903A: Liverpool Telescope optical observations
  31. GRB 260903A: SAO RAS optical observations
  32. GRB 260830A: GECAM-B detection of a burst
  33. EP260903a: EP-WXT detection of a fast X-ray transient
  34. EP Alert 260903.62: Global MASTER-Net observations report
  35. GRB 260830A: Insight-HXMT/HE detection
  36. GRB 260903A: EP-FXT follow-up observation
  37. GRB 260903A: OHP/T193 optical afterglow detection
  38. GRB 260903A: NOT optical observations and afterglow fading
  39. NuSTAR Transient 260828: SOAR Optical Upper Limits
  40. SVOM GRB260903A: Global MASTER-Net observations report
  41. GRB 260903A: LCO optical observations
  42. GRB 260903A: SVOM/VT optical candidate
  43. GRB 260903A: Retraction of optical counterpart of GCN 45501
  44. GRB 260831A: GECAM-B observation
  45. GRB 260903A: LCO optical counterpart detection
  46. GRB 260827A: Insight-HXMT/HE detection
  47. GRB 260903A: SVOM detection of a soft faint burst
  48. EP260901a: SVOM/VT optical upper limits
  49. EP260901a: EP-FXT follow-up observation
  50. Konus-Wind detection of GRB 260829A
  51. GRB 260829A: SVOM/GRM observation
  52. GRB 260818A: ATCA detection of a candidate radio counterpart
  53. EP260830a: EP-FXT follow-up observation
  54. EP260901a: Global MASTER-Net observations report
  55. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  56. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  57. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  58. NuSTAR Transient 260828: LCO Optical Upper Limits
  59. EP260901a: EP-WXT detection of a fast X-ray transient
  60. SVOM trigger sb26083106 is not a GRB
  61. GRB 260829A: AstroSat CZTI detection
  62. GRB 260831B: EP-FXT follow-up observation
  63. GRB 260830A: NuSTAR detection of prompt emission
  64. GRB 260831B: LCO optical upper limits
  65. EP260830a: Global MASTER-Net observations report
  66. EP260830a: EP-WXT detection of a fast X-ray transient
  67. GRB 260827A: SVOM/GRM observation
  68. NuSTAR 260828: a 1100s hard X-ray transient
  69. GRB 260831B: SVOM detection of a possible burst
  70. IPN triangulation of GRB 260829A
  71. GRB 260827A: Glowbug gamma-ray detection
  72. EP260727a: ATCA 10 GHz detection
  73. GRB 260831A: Fermi GBM Final Real-time Localization
  74. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  75. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  76. GRB 260829A: GECAM-B observation of a long burst
  77. GRB 260825A: SVOM/GRM observation of a long burst
  78. GRB 260825A: GECAM-B observation
  79. GRB 260829A: Fermi GBM Detection
  80. GRB 260825A: AstroSat CZTI detection
  81. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  82. GRB 260829A: Fermi GBM Final Real-time Localization
  83. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  85. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  86. Fermi GBM trigger 809666623/260829141 is not a GRB
  87. GRB 260818B: Further EP-FXT observation
  88. GRB 260818B: VLT optical and nIR observations
  89. GRB 260818B: TNG NIR observations
  90. MAXI GRB260827.40: Global MASTER-Net observations report
  91. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  92. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  93. GRB 260827A: Fermi GBM Final Real-time Localization
  94. GRB 260818B: 6 GHz VLA observations
  95. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  96. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  97. GRB 260808B: SAO RAS observations of the optical rebrightening
  98. EP260822a: Global MASTER-Net observations report
  99. EP Alert 260820.31: Global MASTER-Net observations report
  100. IceCube-260825A: No transient candidates from the Zwicky Transient Facility

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