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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"

21731 results found.

  1. GRB 260915A: SVOM/ECLAIRs refined analysis
  2. GRB 260917B: WINTER J-band observations
  3. GRB 260917B: SVOM/VT optical observations
  4. SVOM GRB260917.16: Global MASTER-Net observations report
  5. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  6. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  7. Fermi trigger No 811304653: Global MASTER-Net observations report
  8. GRB 260915A: J-band upper limit with WINTER
  9. Fermi trigger No 811264269: Global MASTER-Net observations report
  10. GRB 260909A: NOEMA detection
  11. GRB 260914A: Mondy and TShAO optical observations
  12. GRB 260914A: SVOM/ECLAIRs refined analysis
  13. GRB 260909A: Swift-XRT observations
  14. MAXI GRB260916.37: Global MASTER-Net observations report
  15. GRB 260915A: Swift ToO observations
  16. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  17. GRB 260915A: SVOM/C-GFT optical upper limits
  18. GRB 260915A: REM optical/NIR observations
  19. GRB 260914A: REM optical/NIR observations
  20. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  21. GRB 260915A: SVOM/VT optical upper limits
  22. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  23. GRB 260915A: NOT optical upper limit
  24. SVOM GRB260915.05: Global MASTER-Net observations report
  25. GRB 260915A: SVOM/VT optical upper limits from VHF data
  26. Fermi GBM Sub-Threshold Detection of GRB 260915A
  27. EP Alert 260914.53: Global MASTER-Net observations report
  28. Fermi GBM Sub-Threshold Detection of GRB 260914A
  29. GRB 260914A: LCO optical observation
  30. GRB 260914A: SVOM/C-GFT optical observations
  31. GRB 260914A: SVOM/VT optical counterpart confirmation
  32. GRB 260914A: SVOM/VT optical observation from VHF data
  33. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  34. SVOM GRB260914.47: Global MASTER-Net observations report
  35. GRB 260818A: Continued ATCA observations
  36. SVOM GRB260913.32: Global MASTER-Net observations report
  37. GRB 260913A: SVOM/C-GFT optical upper limit
  38. GRB 260909A: CrAO and AbAO optical upper limits
  39. GRB 260909A: SVOM/ECLAIRs refined analysis
  40. GRB 260910B: GOTO tentative optical counterpart candidates
  41. GRB 260909A: Swift ToO observations
  42. GRB 260909A: KAIT optical upper limit
  43. GRB 260903A: Swift-XRT observations
  44. EP260806a: VLA+ALMA radio detections
  45. GRB 260909A: OHP/T193 z-band upper limit
  46. EP Alert 260909.53: Global MASTER-Net observations report
  47. EP260806a: NOEMA detection
  48. EP260623a: NOEMA detections
  49. GRB 260909A: Mondy optical observations and afterglow candidate
  50. GRB 260909A: SVOM/C-GFT optical upper limit
  51. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  52. Fermi trigger No 810554827: Global MASTER-Net observations report
  53. EP Alert 260908.60: Global MASTER-Net observations report
  54. GRB 260903A: Swift ToO observations
  55. Fermi GRB 260907B: Global MASTER-Net observations report
  56. GRB 260903A: SAO RAS optical upper limit
  57. Fermi GRB 260907A: Global MASTER-Net observations report
  58. EP260903a: EP-FXT follow-up observation
  59. EP Alert 260905.11: Global MASTER-Net observations report
  60. GRB 260903A: J-band upper limit with WINTER
  61. EP Alert 260903.47: Global MASTER-Net observations report
  62. GRB 260903A: SVOM/ECLAIRs refined analysis
  63. GRB260903A: Liverpool Telescope optical observations
  64. GRB 260903A: SAO RAS optical observations
  65. EP260903a: EP-WXT detection of a fast X-ray transient
  66. EP Alert 260903.62: Global MASTER-Net observations report
  67. GRB 260903A: OHP/T193 optical afterglow detection
  68. GRB 260903A: NOT optical observations and afterglow fading
  69. NuSTAR Transient 260828: SOAR Optical Upper Limits
  70. SVOM GRB260903A: Global MASTER-Net observations report
  71. GRB 260903A: LCO optical observations
  72. GRB 260903A: SVOM/VT optical candidate
  73. GRB 260818A: ATCA detection of a candidate radio counterpart
  74. EP260901a: Global MASTER-Net observations report
  75. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  76. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  77. NuSTAR Transient 260828: LCO Optical Upper Limits
  78. EP260901a: EP-WXT detection of a fast X-ray transient
  79. EP260830a: Global MASTER-Net observations report
  80. EP260830a: EP-WXT detection of a fast X-ray transient
  81. NuSTAR 260828: a 1100s hard X-ray transient
  82. EP260727a: ATCA 10 GHz detection
  83. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  84. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  85. GRB 260818B: VLT optical and nIR observations
  86. GRB 260818B: TNG NIR observations
  87. MAXI GRB260827.40: Global MASTER-Net observations report
  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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