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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"

21801 results found.

  1. GRB 260914A: SVOM/VT optical counterpart confirmation
  2. GRB 260914A: SVOM/VT optical observation from VHF data
  3. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  4. SVOM GRB260914.47: Global MASTER-Net observations report
  5. GRB 260818A: Continued ATCA observations
  6. SVOM GRB260913.32: Global MASTER-Net observations report
  7. GRB 260913A: SVOM/C-GFT optical upper limit
  8. GRB 260909A: CrAO and AbAO optical upper limits
  9. GRB 260909A: SVOM/ECLAIRs refined analysis
  10. GRB 260910B: GOTO tentative optical counterpart candidates
  11. GRB 260909A: Swift ToO observations
  12. GRB 260909A: KAIT optical upper limit
  13. GRB 260903A: Swift-XRT observations
  14. EP260806a: VLA+ALMA radio detections
  15. GRB 260909A: OHP/T193 z-band upper limit
  16. EP Alert 260909.53: Global MASTER-Net observations report
  17. EP260806a: NOEMA detection
  18. EP260623a: NOEMA detections
  19. GRB 260909A: Mondy optical observations and afterglow candidate
  20. GRB 260909A: SVOM/C-GFT optical upper limit
  21. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  22. Fermi trigger No 810554827: Global MASTER-Net observations report
  23. EP Alert 260908.60: Global MASTER-Net observations report
  24. GRB 260903A: Swift ToO observations
  25. Fermi GRB 260907B: Global MASTER-Net observations report
  26. GRB 260903A: SAO RAS optical upper limit
  27. Fermi GRB 260907A: Global MASTER-Net observations report
  28. EP260903a: EP-FXT follow-up observation
  29. EP Alert 260905.11: Global MASTER-Net observations report
  30. GRB 260903A: J-band upper limit with WINTER
  31. EP Alert 260903.47: Global MASTER-Net observations report
  32. GRB 260903A: SVOM/ECLAIRs refined analysis
  33. GRB260903A: Liverpool Telescope optical observations
  34. GRB 260903A: SAO RAS optical observations
  35. EP260903a: EP-WXT detection of a fast X-ray transient
  36. EP Alert 260903.62: Global MASTER-Net observations report
  37. GRB 260903A: OHP/T193 optical afterglow detection
  38. GRB 260903A: NOT optical observations and afterglow fading
  39. NuSTAR Transient 260828: SOAR Optical Upper Limits
  40. SVOM GRB260903A: Global MASTER-Net observations report
  41. GRB 260903A: LCO optical observations
  42. GRB 260903A: SVOM/VT optical candidate
  43. GRB 260818A: ATCA detection of a candidate radio counterpart
  44. EP260901a: Global MASTER-Net observations report
  45. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  46. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  47. NuSTAR Transient 260828: LCO Optical Upper Limits
  48. EP260901a: EP-WXT detection of a fast X-ray transient
  49. EP260830a: Global MASTER-Net observations report
  50. EP260830a: EP-WXT detection of a fast X-ray transient
  51. NuSTAR 260828: a 1100s hard X-ray transient
  52. EP260727a: ATCA 10 GHz detection
  53. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  54. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  55. GRB 260818B: VLT optical and nIR observations
  56. GRB 260818B: TNG NIR observations
  57. MAXI GRB260827.40: Global MASTER-Net observations report
  58. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  59. GRB 260818B: 6 GHz VLA observations
  60. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  61. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  62. GRB 260808B: SAO RAS observations of the optical rebrightening
  63. EP260822a: Global MASTER-Net observations report
  64. EP Alert 260820.31: Global MASTER-Net observations report
  65. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  66. GRB 260807A: EP-FXT follow-up observations
  67. GRB 260822A: SVOM/ECLAIRs refined analysis
  68. GRB 260809A: SVOM/ECLAIRs refined analysis
  69. GRB 260822A: SVOM/VT optical upper limits
  70. IceCube Alert 260825A: Global MASTER-Net observations report
  71. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  72. GRB 260822A: EP/FXT follow-up observations
  73. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  74. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  75. GRB 260822A: GOTO optical counterpart detection
  76. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  77. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  78. EP260822a: Einstein Probe detection of a fast X-ray transient
  79. GRB 260822A: LCO optical upper limits
  80. GRB 260822A: GOTO optical upper limit
  81. GRB 260822A: SVOM detection of a short burst
  82. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  83. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  84. GRB 260818B: VLA radio observations
  85. GRB 260818B: SVOM/C-GFT optical upper limit
  86. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  87. IceCube Alert 260821A: Global MASTER-Net observations report
  88. GRB 260818A: J-band observations with WINTER
  89. GRB 260818B: SVOM/ECLAIRs refined analysis
  90. GRB 260818A: SVOM/ECLAIRs refined analysis
  91. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  92. EP260806a: SAO RAS multicolor optical observations
  93. EP260812a: AbAO optical upper limit
  94. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  95. EP260806a: SVOM/ECLAIRs detection through targeted search
  96. EP260806a: NUTTELA-TAO optical observations
  97. EP260812a: AZT-22 optical upper limit
  98. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  99. EP260806a: WFST optical observations
  100. EP260812b: Optical upper limit with Kinder

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