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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"

2900 results found.

  1. IceCube-231211A: Upper limits from a search for additional neutrino events in IceCube
  2. Fermi-LAT detection of increased gamma-ray activity of blazar PKS 2047+098, located inside the IceCube-231211A error region
  3. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  4. IceCube-231202A: No candidates from the Zwicky Transient Facility
  5. IPN triangulation of GRB 231129C
  6. GRB 231208A: AstroSat CZTI detection of a faint burst
  7. GRB 231205B: Swift detection of a burst
  8. Fermi trigger No 723435916: Global MASTER-Net observations report
  9. Fermi trigger No 723326169: Global MASTER-Net observations report
  10. Fermi trigger No 723412808: Global MASTER-Net observations report
  11. GRB 231203A: Fermi GBM Final Real-time Localization
  12. GRB 231129A : MITSuME Akeno optical upper limits
  13. GRB 231129C: MAXI/GSC detection
  14. GRB 231117A: MeerKAT 1.3GHz detection
  15. GRB 231125A: GRBAlpha detection
  16. GRB 231125A: CALET Gamma-Ray Burst Monitor detection
  17. GRB 231125A (short): Glowbug gamma-ray detection
  18. GRB 231125A: AstroSat CZTI detection of a short burst
  19. GRB 231111A: Optical follow-up observations at Terskol, AbAO, Maidanak, Mondy, Assy
  20. Fermi trigger No 722462310: Global MASTER-Net observations report
  21. GRB 231115A: JinShan optical upper limits
  22. GRB 231116A: Fermi GBM Final Real-time Localization
  23. GRB 231115A: MASTER optical observations
  24. Integral GRB231115.65: Global MASTER-Net observations report
  25. GRB 231115A: GROWTH-India discovery of a potential optical counterpart
  26. Fermi GRB 231115A: Global MASTER-Net observations report
  27. GRB 231104A: VZLUSAT-2 detection
  28. GRB231111A: YAHPT Observations
  29. Swift GRB231110.89: Global MASTER-Net observations report
  30. IceCube-231103A: No candidates from the Zwicky Transient Facility
  31. Fermi GRB 231108A: Global MASTER-Net observations report
  32. GRB 231104A: Swift-BAT refined analysis
  33. Fermi trigger No 721006392: Global MASTER-Net observations report
  34. Fermi GRB 231106A: Global MASTER-Net observations report
  35. GRB 231104A: NuSTAR Observation of the prompt emission
  36. GRB 231104A: Fermi GBM Observation
  37. GRB 231104B: Fermi GBM Final Real-time Localization
  38. Fermi GRB 231103A: Global MASTER-Net observations report
  39. GRB 231104A: AstroSat CZTI detection
  40. GRB 231104A: Fermi-LAT detection
  41. GRB 231104A: Enhanced Swift-XRT position
  42. GRB 231104A: Swift detection of a bright burst
  43. GRB 231104A: Fermi GBM Final Real-time Localization
  44. LIGO/Virgo/KAGRA S231102i: Global MASTER-Net observations report
  45. Fermi GRB 231030B: Global MASTER-Net observations report
  46. IceCube Alert 231027.18: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S231025t: Global MASTER-Net observations report
  48. LIGO/Virgo/KAGRA S231025a: Global MASTER-Net observations report
  49. Fermi trigger No 719846439: Global MASTER-Net observations report
  50. GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
  51. GRB 231012A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705709044)
  52. Fermi GRB 231019A: Global MASTER-Net observations report
  53. GRB 231017A: JinShan optical upper limit
  54. GRB 231015A: Glowbug gamma-ray detection
  55. IceCube-231004A: One Candidate Counterpart from the Zwicky Transient Facility
  56. LIGO/Virgo/KAGRA S230922g: DECam GW-MMADS candidates
  57. GRB 230906A: optical counterpart
  58. Fermi trigger No 716449174: Global MASTER-Net observations report
  59. LIGO/Virgo/KAGRA S230904n: One ZTF candidate counterpart to coincident neutrino event
  60. GRB 230911A: GOTO optical counterpart candidate
  61. GRB 230906A: Chandra detection of the X-ray afterglow
  62. GRB 230911C: Swift detection of a burst
  63. GRB 230906A: Swift-XRT observations
  64. IPN triangulation of GRB 230906A (short)
  65. GRB 230812B: Chandra late-time detection of the X-ray afterglow
  66. Fermi trigger No 715429986: Global MASTER-Net observations report
  67. Fermi GRB 230904A: Global MASTER-Net observations report
  68. GRB 230828A: AstroSat CZTI detection
  69. Fermi GRB 230827A: Global MASTER-Net observations report
  70. GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
  71. GRB 230826A: Swift detection of a burst
  72. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  73. Swift GRB230825.75: Global MASTER-Net observations report
  74. GRB 230812B: radio detection with the VLA
  75. Fermi trigger No 714618399: Global MASTER-Net observations report
  76. GRB 230812B: Assy optical observations, possible SN rise
  77. Swift GRB230820.81: Global MASTER-Net observations report
  78. Fermi GRB 230818A: Global MASTER-Net observations report
  79. Swift GRB230818.98: Global MASTER-Net observations report
  80. IPN triangulation of GRB 230815B
  81. Fermi GRB 230814A: Global MASTER-Net observations report
  82. GRB 230812B: continued AbAO optical afterglow observations
  83. GRB 230812B: Optical observaions from Rozhen Observatory
  84. GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
  85. GRB 230812B: CrAO ZTSh optical observations
  86. GRB 230812B: Koshka Zeiss-1000 optical observations
  87. GRB 230812B: Leavitt Observatory optical observations
  88. GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
  89. GRB 230812B: AbAO optical observations
  90. GRB 230812B: Montarrenti Observatory optical observations
  91. GRB 230812B: Detected Optical Afterglow Candidate
  92. GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
  93. Fermi GRB 230812B: MASTER optical counterpart
  94. GRB 230812B: KAIT Optical Afterglow Candidate
  95. GRB 230812B: Improved Swift/XRT localization
  96. LAT GRB230812.79: Global MASTER-Net observations report
  97. Fermi GRB 230812B: Global MASTER-Net observations report
  98. Fermi trigger No 712991593: Global MASTER-Net observations report
  99. LIGO/Virgo/KAGRA S230731an: AstroSat CZTI non-detection and upper limits
  100. IceCube-230727A: No candidates from the Zwicky Transient Facility

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