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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"

844 results found.

  1. GRB 231129C: Fermi GBM Observation of a very bright GRB
  2. GRB 231129C: iTelescope likely optical afterglow AT 2023yph discovery
  3. GRB 231129C: MAXI/GSC detection
  4. GRB 231129B: Tiled Swift observations
  5. GRB 231129B: MAXI/GSC detection
  6. LIGO/Virgo/KAGRA S231119ab: Coverage and upper limits from MAXI/GSC observations
  7. LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
  8. LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
  9. LIGO/Virgo/KAGRA S231021az: Coverage and upper limits from MAXI/GSC observations
  10. LIGO/Virgo/KAGRA S231020ba: Coverage and upper limits from MAXI/GSC observations
  11. LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
  12. LIGO/Virgo/KAGRA S230917af: Zwicky Transient Facility observations
  13. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  14. LIGO/Virgo/KAGRA S230917af: MAXI/GSC observations
  15. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  16. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  17. LIGO/Virgo/KAGRA S230802aq: Coverage and upper limits from MAXI/GSC observations
  18. LIGO/Virgo/KAGRA S230731an: Coverage and upper limits from MAXI/GSC observations
  19. IceCube-230707A : MAXI upper limit and NICER follow-up observation of Swift J1753.5-0127
  20. Konus-Wind detection of GRB 220623A
  21. LIGO/Virgo/KAGRA S230627c: Coverage and upper limits from MAXI/GSC observations
  22. GRB 230623A: Swift-XRT observations
  23. GRB 230623A: Tiled Swift observations
  24. MAXI GRB 230623A: MASTER optical observations
  25. GRB 230623A: Tiled Swift observations
  26. GRB 230623A: MAXI/GSC detection
  27. LIGO/Virgo/KAGRA S230529ay: Coverage and upper limits from MAXI/GSC observations
  28. GRB 230520A: CALET Gamma-Ray Burst Monitor detection
  29. GRB 230520A: MAXI/GSC detection
  30. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  31. GRB 230510B: Fermi GBM detection
  32. GRB 230510B: AstroSat CZTI detection
  33. GRB 230510B: CALET Gamma-Ray Burst Monitor detection
  34. GRB 230510B: MAXI/GSC detection
  35. MAXI GRB230408.82: Global MASTER-Net observations report
  36. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  37. GRB 230307A: soft X-ray detection with LEIA
  38. GRB 230307A: MAXI/GSC upper limit
  39. GRB 230220A: Correction to GCN 33352
  40. GRB 230220A: MAXI/GSC detection
  41. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  42. GRB 230204B: ATCA radio detection
  43. GRB 230204B: MASTER early OT detection
  44. GRB 230204B: Swift/UVOT Upper Limits
  45. GRB 230204B: Fermi GBM detection
  46. GRB 230204B: Swift-XRT afterglow detection
  47. GRB 230204B: 3.6m DOT optical observation
  48. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  49. GRB 230204B: Swift ToO observations
  50. GRB 230204B: Detection by GRBAlpha
  51. GRB 230204B: AGILE detection
  52. GRB 230204B: GIT discovery of the likely optical afterglow
  53. GRB 230204B: AstroSat CZTI detection
  54. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  55. GRB 230204B: MAXI/GSC detection
  56. GRB 230111A: Fermi GBM Observation
  57. GRB 230111A: MAXI/GSC detection
  58. GRB 221028B: MAXI/GSC detection
  59. Konus-Wind detection of GRB 221017A
  60. GRB 221017A: CALET Gamma-Ray Burst Monitor detection
  61. GRB 221017A: Swift-XRT observations
  62. GRB 221017A: Swift ToO observations
  63. IPN triangulation of GRB 221017A (long)
  64. MAXI GRB221017.24: Global MASTER-Net observations report
  65. GRB 221017A: MAXI/GSC detection
  66. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  67. MAXI GRB 221006A: Redshifts of the possible host galaxies
  68. GRB 221006A: Swift-XRT afterglow detection
  69. Afterglow limits of GRB 221006A from OHP
  70. GRB 221009A: NICER follow-up observations
  71. GRB 221009A: 10.4m GTC spectroscopic redshift confirmation
  72. GRB 221006A: Swift ToO observations
  73. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  74. GRB 221009A BOOTES-2/TELMA and OSN optical detections
  75. GRB 221008A: Swift-XRT observations
  76. GRB 221008A: Tiled Swift observations
  77. GRB 221008A: MAXI/GSC detection
  78. GRB 221006A: Swift-XRT observations
  79. GRB 221006A: Tiled Swift observations
  80. GRB 221006A: MAXI/GSC detection
  81. GRB 220706A: MAXI/GSC detection 84 minutes after the Swift Trigger
  82. MAXI GRB220706.73: Global MASTER-Net observations report
  83. Trigger 1113743: Swift detection of MAXI J0655-013
  84. Swift Detection of MAXI J0655-013
  85. MAXI GRB220607.31: Global MASTER-Net observations report
  86. MAXI GRB220607.41: Global MASTER-Net observations report
  87. Konus-Wind detection of GRB 220506A
  88. Konus-Wind detection of GRB 220514B
  89. GRB 220514B: Swift-XRT observations
  90. GRB 220514B: Tiled Swift observations
  91. GRB 220514B: MAXI/GSC detection
  92. MAXI GRB220514.98: Global MASTER-Net observations report
  93. IceCube Alert 220513.97: Global MASTER-Net observations report
  94. GRB 220506A: MITSuME Akeno optical upper limits
  95. GRB 220506A: GIT optical upper limit.
  96. GRB 220506A: BOOTES-5/JGT optical upper limit
  97. GRB 220506A: Swift-XRT afterglow detection
  98. GRB 220506A: Tiled Swift observations
  99. GRB 220506A/MAXI J1558-266: MAXI/GSC detection
  100. MAXI GRB220506.27: Global MASTER-Net observations report

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