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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"

42753 results found.

  1. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  2. GRB 260907A: SVOM/GRM observation
  3. GRB 260909A: CrAO and AbAO optical upper limits
  4. GRB 260909A: SVOM/ECLAIRs refined analysis
  5. GRB 260910B: GOTO tentative optical counterpart candidates
  6. GRB 260909A: Swift ToO observations
  7. GRB 260910B: Fermi GBM Final Real-time Localization
  8. GRB 260909A: KAIT optical upper limit
  9. GRB 260903A: Swift-XRT observations
  10. EP260806a: VLA+ALMA radio detections
  11. GRB 260909A: OHP/T193 z-band upper limit
  12. GRB 260909A: VLT optical and near-infrared upper limits
  13. EP Alert 260909.53: Global MASTER-Net observations report
  14. GRB 260909A: EP-FXT follow-up observation
  15. GRB 260910A: Fermi GBM Final Real-time Localization
  16. EP260806a: NOEMA detection
  17. EP260623a: NOEMA detections
  18. GRB 260909A: SVOM/VT optical upper limits
  19. GRB 260909A: SVOM/GRM observation
  20. GRB 260909A: Mondy optical observations and afterglow candidate
  21. GRB 260909A: SVOM/C-GFT optical upper limit
  22. GRB 260909A: SVOM detection of a burst
  23. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  24. Fermi trigger No 810554827: Global MASTER-Net observations report
  25. EP Alert 260908.60: Global MASTER-Net observations report
  26. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  27. GRB 260903A: Swift ToO observations
  28. Fermi GRB 260907B: Global MASTER-Net observations report
  29. GRB 260903A: SAO RAS optical upper limit
  30. The EP-WXT trigger 01709305715 is likely a flaring star
  31. GRB 260907B: Fermi GBM Final Real-time Localization
  32. Fermi GRB 260907A: Global MASTER-Net observations report
  33. GRB 260907A: Fermi GBM Final Real-time Localization
  34. EP260903a: EP-FXT follow-up observation
  35. EP Alert 260905.11: Global MASTER-Net observations report
  36. The EP-WXT trigger 01709302592 is likely a flaring star
  37. GRB 260903A: J-band upper limit with WINTER
  38. EP Alert 260903.47: Global MASTER-Net observations report
  39. GRB 260903A: SVOM/ECLAIRs refined analysis
  40. GRB260903A: Liverpool Telescope optical observations
  41. GRB 260903A: SAO RAS optical observations
  42. GRB 260830A: GECAM-B detection of a burst
  43. EP260903a: EP-WXT detection of a fast X-ray transient
  44. EP Alert 260903.62: Global MASTER-Net observations report
  45. GRB 260830A: Insight-HXMT/HE detection
  46. GRB 260903A: EP-FXT follow-up observation
  47. GRB 260903A: OHP/T193 optical afterglow detection
  48. GRB 260903A: NOT optical observations and afterglow fading
  49. NuSTAR Transient 260828: SOAR Optical Upper Limits
  50. SVOM GRB260903A: Global MASTER-Net observations report
  51. GRB 260903A: LCO optical observations
  52. GRB 260903A: SVOM/VT optical candidate
  53. GRB 260831A: GECAM-B observation
  54. GRB 260903A: LCO optical counterpart detection
  55. GRB 260827A: Insight-HXMT/HE detection
  56. GRB 260903A: SVOM detection of a soft faint burst
  57. EP260901a: SVOM/VT optical upper limits
  58. EP260901a: EP-FXT follow-up observation
  59. Konus-Wind detection of GRB 260829A
  60. GRB 260829A: SVOM/GRM observation
  61. GRB 260818A: ATCA detection of a candidate radio counterpart
  62. EP260830a: EP-FXT follow-up observation
  63. EP260901a: Global MASTER-Net observations report
  64. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  65. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  66. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  67. NuSTAR Transient 260828: LCO Optical Upper Limits
  68. EP260901a: EP-WXT detection of a fast X-ray transient
  69. GRB 260829A: AstroSat CZTI detection
  70. GRB 260831B: EP-FXT follow-up observation
  71. GRB 260830A: NuSTAR detection of prompt emission
  72. GRB 260831B: LCO optical upper limits
  73. EP260830a: Global MASTER-Net observations report
  74. EP260830a: EP-WXT detection of a fast X-ray transient
  75. GRB 260827A: SVOM/GRM observation
  76. NuSTAR 260828: a 1100s hard X-ray transient
  77. GRB 260831B: SVOM detection of a possible burst
  78. IPN triangulation of GRB 260829A
  79. GRB 260827A: Glowbug gamma-ray detection
  80. EP260727a: ATCA 10 GHz detection
  81. GRB 260831A: Fermi GBM Final Real-time Localization
  82. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  83. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  84. GRB 260829A: GECAM-B observation of a long burst
  85. GRB 260825A: SVOM/GRM observation of a long burst
  86. GRB 260825A: GECAM-B observation
  87. GRB 260829A: Fermi GBM Detection
  88. GRB 260825A: AstroSat CZTI detection
  89. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  90. GRB 260829A: Fermi GBM Final Real-time Localization
  91. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  92. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  93. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 260818B: Further EP-FXT observation
  95. GRB 260818B: VLT optical and nIR observations
  96. GRB 260818B: TNG NIR observations
  97. MAXI GRB260827.40: Global MASTER-Net observations report
  98. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  99. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  100. GRB 260827A: Fermi GBM Final Real-time Localization

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