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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"

45629 results found.

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

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