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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"

45645 results found.

  1. GRB 260914A: SVOM/C-GFT optical observations
  2. GRB 260914A: SVOM/VT optical counterpart confirmation
  3. GRB 260914A: SVOM/VT optical observation from VHF data
  4. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  5. SVOM GRB260914.47: Global MASTER-Net observations report
  6. GRB 260914A: SVOM detection of a burst
  7. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  8. GRB 260818A: Continued ATCA observations
  9. SVOM GRB260913.32: Global MASTER-Net observations report
  10. GRB 260913A: SVOM/C-GFT optical upper limit
  11. GRB 260913A: SVOM detection of a faint burst
  12. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  13. GRB 260907A: SVOM/GRM observation
  14. GRB 260909A: CrAO and AbAO optical upper limits
  15. GRB 260909A: SVOM/ECLAIRs refined analysis
  16. GRB 260910B: GOTO tentative optical counterpart candidates
  17. GRB 260909A: Swift ToO observations
  18. GRB 260910B: Fermi GBM Final Real-time Localization
  19. GRB 260909A: KAIT optical upper limit
  20. GRB 260903A: Swift-XRT observations
  21. EP260806a: VLA+ALMA radio detections
  22. GRB 260909A: OHP/T193 z-band upper limit
  23. GRB 260909A: VLT optical and near-infrared upper limits
  24. EP Alert 260909.53: Global MASTER-Net observations report
  25. GRB 260909A: EP-FXT follow-up observation
  26. GRB 260910A: Fermi GBM Final Real-time Localization
  27. EP260806a: NOEMA detection
  28. EP260623a: NOEMA detections
  29. GRB 260909A: SVOM/VT optical upper limits
  30. GRB 260909A: SVOM/GRM observation
  31. GRB 260909A: Mondy optical observations and afterglow candidate
  32. GRB 260909A: Xinglong 2.16m optical upper limit
  33. GRB 260909A: SVOM/C-GFT optical upper limit
  34. GRB 260909A: SVOM detection of a burst
  35. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  36. Fermi trigger No 810554827: Global MASTER-Net observations report
  37. EP Alert 260908.60: Global MASTER-Net observations report
  38. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  39. GRB 260903A: Swift ToO observations
  40. Fermi GRB 260907B: Global MASTER-Net observations report
  41. GRB 260903A: SAO RAS optical upper limit
  42. The EP-WXT trigger 01709305715 is likely a flaring star
  43. GRB 260907B: Fermi GBM Final Real-time Localization
  44. Fermi GRB 260907A: Global MASTER-Net observations report
  45. GRB 260907A: Fermi GBM Final Real-time Localization
  46. EP260903a: EP-FXT follow-up observation
  47. EP Alert 260905.11: Global MASTER-Net observations report
  48. The EP-WXT trigger 01709302592 is likely a flaring star
  49. GRB 260903A: J-band upper limit with WINTER
  50. EP Alert 260903.47: Global MASTER-Net observations report
  51. GRB 260903A: SVOM/ECLAIRs refined analysis
  52. GRB260903A: Liverpool Telescope optical observations
  53. GRB 260903A: SAO RAS optical observations
  54. GRB 260830A: GECAM-B detection of a burst
  55. EP260903a: EP-WXT detection of a fast X-ray transient
  56. EP Alert 260903.62: Global MASTER-Net observations report
  57. GRB 260830A: Insight-HXMT/HE detection
  58. GRB 260903A: EP-FXT follow-up observation
  59. GRB 260903A: OHP/T193 optical afterglow detection
  60. GRB 260903A: NOT optical observations and afterglow fading
  61. NuSTAR Transient 260828: SOAR Optical Upper Limits
  62. SVOM GRB260903A: Global MASTER-Net observations report
  63. GRB 260903A: LCO optical observations
  64. GRB 260903A: SVOM/VT optical candidate
  65. GRB 260903A: Retraction of optical counterpart of GCN 45501
  66. GRB 260831A: GECAM-B observation
  67. GRB 260903A: LCO optical counterpart detection
  68. GRB 260827A: Insight-HXMT/HE detection
  69. GRB 260903A: SVOM detection of a soft faint burst
  70. EP260901a: SVOM/VT optical upper limits
  71. EP260901a: EP-FXT follow-up observation
  72. Konus-Wind detection of GRB 260829A
  73. GRB 260829A: SVOM/GRM observation
  74. GRB 260818A: ATCA detection of a candidate radio counterpart
  75. EP260830a: EP-FXT follow-up observation
  76. EP260901a: Global MASTER-Net observations report
  77. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  78. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  79. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  80. NuSTAR Transient 260828: LCO Optical Upper Limits
  81. EP260901a: EP-WXT detection of a fast X-ray transient
  82. SVOM trigger sb26083106 is not a GRB
  83. GRB 260829A: AstroSat CZTI detection
  84. GRB 260831B: EP-FXT follow-up observation
  85. GRB 260830A: NuSTAR detection of prompt emission
  86. GRB 260831B: LCO optical upper limits
  87. EP260830a: Global MASTER-Net observations report
  88. EP260830a: EP-WXT detection of a fast X-ray transient
  89. GRB 260827A: SVOM/GRM observation
  90. NuSTAR 260828: a 1100s hard X-ray transient
  91. GRB 260831B: SVOM detection of a possible burst
  92. IPN triangulation of GRB 260829A
  93. GRB 260827A: Glowbug gamma-ray detection
  94. EP260727a: ATCA 10 GHz detection
  95. GRB 260831A: Fermi GBM Final Real-time Localization
  96. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  97. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  98. GRB 260829A: GECAM-B observation of a long burst
  99. GRB 260825A: SVOM/GRM observation of a long burst
  100. GRB 260825A: GECAM-B observation

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