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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"

23403 results found.

  1. GRB 260925A: Swift/UVOT Upper Limits
  2. GRB 260923A: Glowbug gamma-ray detection
  3. GRB 260924A: Optical follow-up observations with Kinder
  4. GRB 260922A: Glowbug gamma-ray detection
  5. GRB 260925A: Enhanced Swift-XRT position
  6. GRB 260925A: COLIBRÍ optical upper limits
  7. GRB 260925A: FRAM-Auger optical limit
  8. GRB 260924A: Ondrejov D50 optical afterglow detection
  9. EP260924a: J-band upper limit with WINTER
  10. GRB 260924A: SVOM/GRM observation
  11. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  12. GRB 260925A: Swift detection of a burst
  13. EP260924a: EP-WXT detection of an X-ray transient
  14. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  15. GRB 260924A: Swift/UVOT Detection
  16. GRB 260924A: GROWTH-India Telescope optical observations
  17. GRB 260921A: SVOM/GRM observation
  18. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  19. GRB 260920A: SVOM/GRM observation
  20. GRB 260924A: NOT optical counterpart confirmation
  21. GRB 260924A: Enhanced Swift-XRT position
  22. GRB 260924A: Swift detection of a burst
  23. EP260806a: e-MERLIN detection at 5 GHz
  24. GRB 260922A: Ondrejov D50 optical limit
  25. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  26. GRB 260922A: J-band upper limit with WINTER
  27. GRB 260922A: Swift/UVOT Upper Limits
  28. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  29. GRB 260922A: COLIBRÍ optical upper limits
  30. GRB 260922A: Enhanced Swift-XRT position
  31. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  32. GRB 260920A: Glowbug gamma-ray detection
  33. GRB 260922A: SVOM/C-GFT optical upper limit
  34. GRB 260922A: Swift detection of a burst
  35. GRB 260917C: AstroSat CZTI detection
  36. GRB 260921A: Fermi GBM Observation
  37. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  38. EP260920a: VLT/HAWK-I near-infrared candidate
  39. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  40. GRB 260921A: Swift detection of a burst
  41. EP260920b: LCO observations
  42. GRB 260920A: AstroSat CZTI detection
  43. EP260920b: SVOM/VT optical observation
  44. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  45. EP260920b: COLIBRÍ optical observations
  46. EP260920b: LCO optical counterpart detection
  47. EP260920b: Einstein Probe detection of an X-ray transient
  48. EP-WXT detected a brightening of HMXB LS V +44 17
  49. EP260920a: NOT early time optical upper limits
  50. EP260920a: NOT optical upper limits
  51. EP260920a: SVOM/VT optical upper limits
  52. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  53. EP260920a: COLIBRÍ optical upper limits
  54. EP260920a: LCO optical counterpart candidate
  55. EP260920a: Einstein Probe detection of an X-ray transient
  56. GRB 260915A: VLT optical and near-infrared upper limits
  57. EP260806a: Yamaguchi Interferometer radio detections
  58. EP260917a: SVOM/VT optical upper limits
  59. GRB 260918A: SVOM/C-GFT optical upper limits
  60. GRB 260916B: Glowbug gamma-ray detection of a short burst
  61. GRB 260917B: Mondy optical upper limit
  62. IPN triangulation of GRB 260916B (short)
  63. EP260917b: EP-WXT detection of an X-ray transient
  64. EP260917A: J-band upper limit with WINTER
  65. IPN triangulation of GRB 260810A
  66. GRB 260917B: EP-FXT follow-up observation
  67. EP260917a: COLIBRÍ optical upper limits
  68. GRB 260915A: Swift-XRT afterglow detection
  69. GRB 260918A: LCO optical upper limits
  70. EP260917a: Einstein Probe detection of an X-ray transient
  71. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  72. GRB 260918A: SVOM detection of a burst
  73. GRB 260917B: FRAM-Auger optical limits
  74. GRB 260917A: Glowbug gamma-ray detection
  75. GRB 260917B: WINTER J-band observations
  76. GRB 260917B: SVOM/VT optical observations
  77. GRB 260917B: LCO optical observation
  78. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  79. GRB 260917B: SVOM detection of a faint burst
  80. GRB 260915A: J-band upper limit with WINTER
  81. GRB 260909A: NOEMA detection
  82. GRB 260914A: SVOM/GRM observation
  83. GRB 260914A: Mondy and TShAO optical observations
  84. GRB 260909A: Swift-XRT observations
  85. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  86. GRB 260915A: SVOM/C-GFT optical upper limits
  87. GRB 260915A: SVOM/VT refined early optical upper limits
  88. GRB 260915A: REM optical/NIR observations
  89. GRB 260914A: REM optical/NIR observations
  90. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  91. GRB 260915A: SVOM/VT optical upper limits
  92. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 260915A: 10.4m GTC deep optical limits
  94. GRB 260915A: NOT optical upper limit
  95. GRB 260915A: SVOM/VT optical upper limits from VHF data
  96. GRB 260915A: LCO optical upper limits
  97. EP Alert 260914.53: Global MASTER-Net observations report
  98. GRB 260915A: SVOM detection of a burst
  99. GRB 260914A: LCO optical observation
  100. GRB 260914A: SVOM/C-GFT optical observations

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