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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"

36146 results found.

  1. GRB 231017A: GOTO optical upper limits
  2. GRB 231017A: JinShan optical upper limit
  3. GRB 231018A: GROWTH-India Follow-Up of a Fermi Long GRB
  4. GRB 231017A: Las Cumbres optical upper limit
  5. GRB 231015A: Glowbug gamma-ray detection
  6. GRB 231017A: LCOGT Optical Upper Limits
  7. GRB231017A: GROWTH-India upper limits on the optical afterglow
  8. GRB 231015A: AstroSat CZTI detection
  9. GRB 231018A: Fermi GBM Detection
  10. GRB 231017A: Fermi GBM Detection
  11. GRB 231017A: Swift-XRT observations
  12. GRB 231012B may not be a GRB
  13. GRB 231018A: BALROG localization (Fermi Trigger / GRB 231018521)
  14. GRB 231018A: Fermi GBM Final Real-time Localization
  15. GRB 231017A: Swift ToO observations
  16. GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
  17. GRB231017A: Fermi GBM Final Localization
  18. IceCube-231014A: Upper limits from a search for additional neutrino events in IceCube
  19. LIGO/Virgo/KAGRA S231014r: Upper limits from Swift/BAT-GUANO
  20. Correction in GCN 34814: GRB 231012B (not GRB 231012A)
  21. GRB 231012A: Fermi GBM Final Real-time Localization
  22. GRB 231012A: Fermi GBM Final Real-time Localization
  23. GRB 231004A: Glowbug gamma-ray detection
  24. LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO
  25. IceCube-231004A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 231004A: CALET Gamma-Ray Burst Monitor detection
  27. Update of IceCube-231004A - Corrected direciton
  28. GRB 231004A: Fermi GBM Final Real-time Localization
  29. GRB 231003A is not a GRB
  30. GRB 231003A: Fermi GBM Final Real-time Localization
  31. LIGO/Virgo/KAGRA S231001aq: Upper limits from Swift/BAT-GUANO
  32. LIGO/Virgo/KAGRA S230930al: Upper limits from Swift/BAT-GUANO
  33. LIGO/Virgo/KAGRA S230928cb: Upper limits from Swift/BAT-GUANO
  34. GRB 230827B: 10.4m GTC spectroscopic redshift
  35. GRB 230930A: Fermi GBM Final Real-time Localization
  36. AT2023sva / GRB230916B: GIT observations of the afterglow
  37. transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
  38. Swift Triggers 1192740, 1192742 and 1192743 are not astrophysical events
  39. Konus-Wind detection of GRB 230919A
  40. LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
  41. LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
  42. LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
  43. Fermi Gamma-ray Burst Monitor trigger 717299390/230925076 is not a GRB
  44. Fermi Gamma-ray Burst Monitor trigger 230925241/717313591 is not a GRB
  45. GRB 230812B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
  46. GRB 230921A: Fermi GBM Final Real-time Localization
  47. GRB 230918B: VLT/X-shooter classification of AT 2023tbf (GOTO23aky) as a dwarf nova
  48. IPN triangulation of GRB 230919A (short)
  49. GRB 230919A: Fermi GBM Observation
  50. Fermi GBM Statement for Trigger 716527670/230916144
  51. GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
  52. GRB 230812B : optical observations from MISTRAL at Observatoire de Haute-Provence
  53. GRB 230919A: AstroSat CZTI detection
  54. AT2023sva: redshift from OSIRIS+/GTC of the ZTF afterglow
  55. GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
  56. GRB 230919A: Fermi GBM Final Real-time Localization
  57. Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
  58. GRB 230918B: Fermi GBM Final Real-time Localization
  59. GRB 230918A (short): Glowbug gamma-ray detection
  60. GRB 230916B: Glowbug gamma-ray detection
  61. ZTF and SEDM Observations of the Candidate Optical Afterglow AT 2023sva
  62. GRB 230915A: Fermi GBM observation
  63. GRB 230812B: Radio observations with the uGMRT
  64. GRB 230918A: Fermi GBM Final Real-time Localization
  65. GRB 230917A: AstroSat CZTI detection
  66. GRB 230915B: Glowbug gamma-ray detection
  67. GRB 230916A: NuSTAR Discovery of Prompt Emission from a Potential GRB
  68. GRB 230911A: Fermi GBM Observation
  69. GRB 230915A: Swift/BAT-GUANO detection of a burst
  70. LIGO/Virgo/KAGRA S230914ak: Upper limits from Swift/BAT-GUANO
  71. GRB 230911D: GRBAlpha detection
  72. Swift Trigger 1192233 is not a GRB
  73. GRB 230906A: optical counterpart
  74. IceCube-230914A: Upper limits from a search for additional neutrino events in IceCube
  75. GRB 230911A: Swift-XRT afterglow detection
  76. GRB 230913A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 230913A: Glowbug gamma-ray detection
  78. GRB 230812B: Bad Time Intervals for Fermi GBM data
  79. GRB 230913A: Fermi GBM Observation
  80. Swift Trigger 1191904 is not a GRB
  81. GRB 230911A: Swift ToO observations
  82. GRB 230913A: Swift/BAT-GUANO arcminute localization of a burst
  83. Fermi GRB 230913A: Global MASTER-Net observations report
  84. GRB 230911A: GOTO optical counterpart candidate
  85. GRB 230913A: Fermi GBM Final Real-time Localization
  86. GRB 230908A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 230911D: NuSTAR Detection of Prompt Emission
  88. GRB 230911B: AstroSat CZTI detection
  89. GRB 230911C: Swift-XRT refined Analysis
  90. GRB 230911C: Swift-BAT refined analysis
  91. GRB230911C: BOOTES-6/DPRT optical upper limit
  92. GRB 230906A: Chandra detection of the X-ray afterglow
  93. Swift GRB 230911C: Global MASTER-Net observations report
  94. GRB 230911D: Fermi GBM observation
  95. IPN triangulation of GRB 230911D (long)
  96. GRB 230911D: Fermi-LAT detection
  97. GRB230911C: LCOGT Optical Upper Limits
  98. GRB 230911C: Swift/UVOT Upper Limits
  99. GRB 230911B: GRBAlpha and VZLUSAT-2 joint detection
  100. GRB 230911C: GOTO optical upper limits

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