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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"

41677 results found.

  1. EP260806a: VLA+ALMA radio detections
  2. GRB 260909A: OHP/T193 z-band upper limit
  3. GRB 260909A: VLT optical and near-infrared upper limits
  4. EP Alert 260909.53: Global MASTER-Net observations report
  5. GRB 260909A: EP-FXT follow-up observation
  6. EP260806a: NOEMA detection
  7. EP260623a: NOEMA detections
  8. GRB 260909A: SVOM/VT optical upper limits
  9. GRB 260909A: SVOM/GRM observation
  10. GRB 260909A: Mondy optical observations and afterglow candidate
  11. GRB 260909A: Xinglong 2.16m optical upper limit
  12. GRB 260909A: SVOM/C-GFT optical upper limit
  13. GRB 260909A: SVOM detection of a burst
  14. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  15. Fermi trigger No 810554827: Global MASTER-Net observations report
  16. EP Alert 260908.60: Global MASTER-Net observations report
  17. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  18. GRB 260903A: Swift ToO observations
  19. Fermi GRB 260907B: Global MASTER-Net observations report
  20. GRB 260903A: SAO RAS optical upper limit
  21. The EP-WXT trigger 01709305715 is likely a flaring star
  22. Fermi GRB 260907A: Global MASTER-Net observations report
  23. EP260903a: EP-FXT follow-up observation
  24. EP Alert 260905.11: Global MASTER-Net observations report
  25. The EP-WXT trigger 01709302592 is likely a flaring star
  26. GRB 260903A: J-band upper limit with WINTER
  27. EP Alert 260903.47: Global MASTER-Net observations report
  28. GRB 260903A: SVOM/ECLAIRs refined analysis
  29. GRB260903A: Liverpool Telescope optical observations
  30. GRB 260903A: SAO RAS optical observations
  31. GRB 260830A: GECAM-B detection of a burst
  32. EP260903a: EP-WXT detection of a fast X-ray transient
  33. EP Alert 260903.62: Global MASTER-Net observations report
  34. GRB 260830A: Insight-HXMT/HE detection
  35. GRB 260903A: EP-FXT follow-up observation
  36. GRB 260903A: OHP/T193 optical afterglow detection
  37. GRB 260903A: NOT optical observations and afterglow fading
  38. NuSTAR Transient 260828: SOAR Optical Upper Limits
  39. SVOM GRB260903A: Global MASTER-Net observations report
  40. GRB 260903A: LCO optical observations
  41. GRB 260903A: SVOM/VT optical candidate
  42. GRB 260903A: Retraction of optical counterpart of GCN 45501
  43. GRB 260831A: GECAM-B observation
  44. GRB 260903A: LCO optical counterpart detection
  45. GRB 260827A: Insight-HXMT/HE detection
  46. GRB 260903A: SVOM detection of a soft faint burst
  47. EP260901a: SVOM/VT optical upper limits
  48. EP260901a: EP-FXT follow-up observation
  49. Konus-Wind detection of GRB 260829A
  50. GRB 260829A: SVOM/GRM observation
  51. GRB 260818A: ATCA detection of a candidate radio counterpart
  52. EP260830a: EP-FXT follow-up observation
  53. EP260901a: Global MASTER-Net observations report
  54. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  55. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  56. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  57. NuSTAR Transient 260828: LCO Optical Upper Limits
  58. EP260901a: EP-WXT detection of a fast X-ray transient
  59. SVOM trigger sb26083106 is not a GRB
  60. GRB 260829A: AstroSat CZTI detection
  61. GRB 260831B: EP-FXT follow-up observation
  62. GRB 260830A: NuSTAR detection of prompt emission
  63. GRB 260831B: LCO optical upper limits
  64. EP260830a: Global MASTER-Net observations report
  65. EP260830a: EP-WXT detection of a fast X-ray transient
  66. GRB 260827A: SVOM/GRM observation
  67. NuSTAR 260828: a 1100s hard X-ray transient
  68. GRB 260831B: SVOM detection of a possible burst
  69. IPN triangulation of GRB 260829A
  70. GRB 260827A: Glowbug gamma-ray detection
  71. EP260727a: ATCA 10 GHz detection
  72. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  73. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  74. GRB 260829A: GECAM-B observation of a long burst
  75. GRB 260825A: SVOM/GRM observation of a long burst
  76. GRB 260825A: GECAM-B observation
  77. GRB 260829A: Fermi GBM Detection
  78. GRB 260825A: AstroSat CZTI detection
  79. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  80. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  81. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  82. Fermi GBM trigger 809666623/260829141 is not a GRB
  83. GRB 260818B: Further EP-FXT observation
  84. GRB 260818B: VLT optical and nIR observations
  85. GRB 260818B: TNG NIR observations
  86. MAXI GRB260827.40: Global MASTER-Net observations report
  87. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  88. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  89. GRB 260818B: 6 GHz VLA observations
  90. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  91. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  92. GRB 260808B: SAO RAS observations of the optical rebrightening
  93. EP260822a: Global MASTER-Net observations report
  94. EP Alert 260820.31: Global MASTER-Net observations report
  95. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  96. GRB 260807A: EP-FXT follow-up observations
  97. GRB 260822A: SVOM/ECLAIRs refined analysis
  98. GRB 260809A: SVOM/ECLAIRs refined analysis
  99. GRB 260822A: SVOM/VT optical upper limits
  100. IceCube Alert 260825A: Global MASTER-Net observations report

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