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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"

24353 results found.

  1. GRB 260914A: REM optical/NIR observations
  2. GRB 260915A: SVOM/VT optical upper limits
  3. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  4. SVOM GRB260915.05: Global MASTER-Net observations report
  5. GRB 260915A: SVOM/VT optical upper limits from VHF data
  6. Fermi GBM Sub-Threshold Detection of GRB 260915A
  7. GRB 260915A: LCO optical upper limits
  8. EP Alert 260914.53: Global MASTER-Net observations report
  9. GRB 260914A: EP-FXT follow-up observation
  10. GRB 260915A: SVOM detection of a burst
  11. Fermi GBM Sub-Threshold Detection of GRB 260914A
  12. GRB 260914A: LCO optical observation
  13. GRB 260914A: SVOM/C-GFT optical observations
  14. GRB 260914A: SVOM/VT optical counterpart confirmation
  15. GRB 260914A: SVOM/VT optical observation from VHF data
  16. SVOM GRB260914.47: Global MASTER-Net observations report
  17. GRB 260914A: SVOM detection of a burst
  18. SVOM GRB260913.32: Global MASTER-Net observations report
  19. GRB 260913A: SVOM/C-GFT optical upper limit
  20. GRB 260913A: SVOM detection of a faint burst
  21. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  22. GRB 260907A: SVOM/GRM observation
  23. GRB 260909A: CrAO and AbAO optical upper limits
  24. GRB 260909A: SVOM/ECLAIRs refined analysis
  25. GRB 260910B: GOTO tentative optical counterpart candidates
  26. GRB 260910B: Fermi GBM Final Real-time Localization
  27. GRB 260909A: KAIT optical upper limit
  28. EP260806a: VLA+ALMA radio detections
  29. GRB 260909A: OHP/T193 z-band upper limit
  30. GRB 260909A: VLT optical and near-infrared upper limits
  31. EP Alert 260909.53: Global MASTER-Net observations report
  32. GRB 260909A: EP-FXT follow-up observation
  33. GRB 260910A: Fermi GBM Final Real-time Localization
  34. GRB 260909A: SVOM/VT optical upper limits
  35. GRB 260909A: SVOM/GRM observation
  36. GRB 260909A: SVOM/C-GFT optical upper limit
  37. GRB 260909A: SVOM detection of a burst
  38. Fermi trigger No 810554827: Global MASTER-Net observations report
  39. EP Alert 260908.60: Global MASTER-Net observations report
  40. Fermi GRB 260907B: Global MASTER-Net observations report
  41. The EP-WXT trigger 01709305715 is likely a flaring star
  42. GRB 260907B: Fermi GBM Final Real-time Localization
  43. Fermi GRB 260907A: Global MASTER-Net observations report
  44. GRB 260907A: Fermi GBM Final Real-time Localization
  45. EP260903a: EP-FXT follow-up observation
  46. EP Alert 260905.11: Global MASTER-Net observations report
  47. The EP-WXT trigger 01709302592 is likely a flaring star
  48. EP Alert 260903.47: Global MASTER-Net observations report
  49. GRB 260903A: SVOM/ECLAIRs refined analysis
  50. GRB 260903A: SAO RAS optical observations
  51. GRB 260830A: GECAM-B detection of a burst
  52. EP Alert 260903.62: Global MASTER-Net observations report
  53. GRB 260903A: EP-FXT follow-up observation
  54. GRB 260903A: OHP/T193 optical afterglow detection
  55. NuSTAR Transient 260828: SOAR Optical Upper Limits
  56. SVOM GRB260903A: Global MASTER-Net observations report
  57. GRB 260903A: LCO optical observations
  58. GRB 260903A: SVOM/VT optical candidate
  59. GRB 260903A: LCO optical counterpart detection
  60. GRB 260903A: SVOM detection of a soft faint burst
  61. EP260901a: SVOM/VT optical upper limits
  62. EP260901a: EP-FXT follow-up observation
  63. Konus-Wind detection of GRB 260829A
  64. GRB 260829A: SVOM/GRM observation
  65. EP260830a: EP-FXT follow-up observation
  66. EP260901a: Global MASTER-Net observations report
  67. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  68. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  69. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  70. GRB 260829A: AstroSat CZTI detection
  71. GRB 260831B: EP-FXT follow-up observation
  72. GRB 260830A: NuSTAR detection of prompt emission
  73. GRB 260831B: LCO optical upper limits
  74. EP260830a: Global MASTER-Net observations report
  75. GRB 260827A: SVOM/GRM observation
  76. GRB 260831B: SVOM detection of a possible burst
  77. IPN triangulation of GRB 260829A
  78. GRB 260831A: Fermi GBM Final Real-time Localization
  79. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  80. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  81. GRB 260829A: GECAM-B observation of a long burst
  82. GRB 260825A: SVOM/GRM observation of a long burst
  83. GRB 260829A: Fermi GBM Detection
  84. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  85. GRB 260829A: Fermi GBM Final Real-time Localization
  86. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  87. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  88. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  89. GRB 260818B: Further EP-FXT observation
  90. GRB 260818B: TNG NIR observations
  91. MAXI GRB260827.40: Global MASTER-Net observations report
  92. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  93. GRB 260827A: Fermi GBM Final Real-time Localization
  94. GRB 260818B: 6 GHz VLA observations
  95. EP260822a: Global MASTER-Net observations report
  96. EP Alert 260820.31: Global MASTER-Net observations report
  97. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  98. GRB 260807A: EP-FXT follow-up observations
  99. GRB 260822A: SVOM/ECLAIRs refined analysis
  100. GRB 260809A: SVOM/ECLAIRs refined analysis

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