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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"
  1. GRB 231222A: Fermi GBM Final Real-time Localization
  2. GRB 231220A: Swift-XRT follow-up observations
  3. GRB 231220A: Swift ToO observations
  4. GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
  5. Fermi trigger No 724781422: Global MASTER-Net observations report
  6. GRB 231220A: Fermi GBM Final Real-time Localization
  7. GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
  8. Fermi trigger No 724698747: Global MASTER-Net observations report
  9. GRB 231219A: Fermi GBM Final Real-time Localization
  10. GRID detection of GRB 231205B
  11. GRID detection of GRB 231205A
  12. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  13. GRB 231214B: Fermi GBM observation
  14. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  15. GRB 231216A: 10.4 m GTC optical upper limit
  16. GRB 231215A: AMI-LA radio detection
  17. GRB 231216A: Nanshan/HMT optical upper limit
  18. GRB 231216A: LCOGT Optical Upper Limits
  19. GRB 231216A: Osservatorio Astronomico Nastro Verde upper limit
  20. GRB 231216A: Swift-XRT refined analysis correction
  21. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  22. GRB 231216A: Swift-XRT refined Analysis
  23. GRB 231216A: AST3-3 YaoAn Optical Upper Limit
  24. GRB 231216A: REM NIR upper limits
  25. GRB 231216A: Swift/UVOT Upper Limits
  26. GRB 231216A: Swift-BAT refined analysis
  27. GRB 231215A: Swift-BAT refined analysis
  28. GRB 231214A: Swift-BAT refined analysis
  29. GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
  30. GRB 231216A: GIT optical upper limit
  31. GRB 231216A: NOT optical upper limits
  32. GRB 231216A: BOOTES-2/TELMA optical upper limit
  33. GRB 231215A: GRBAlpha detection
  34. Swift GRB231216.77: Global MASTER-Net observations report
  35. GRB 231216A: Swift detection of a burst
  36. Konus-Wind detection of GRB 231215A
  37. GRB 231215A: optical afterglow detection from the INAF Asiago Observatory
  38. GRB 231215A: NOT optical observations
  39. GRB 231214A: Swift/UVOT Upper Limits
  40. GRB 231215A: Redshift from OSIRIS+ / GTC
  41. GRB 231205B: VZLUSAT-2 detection
  42. GRB 231204A: VZLUSAT-2 detection
  43. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  44. GRB 231215A: Fermi GBM observation
  45. GRB 231215A: CALET Gamma-Ray Burst Monitor detection
  46. GRB 231215A : OHP/T193 optical afterglow detection
  47. GRB 231215A: Swift/UVOT Detection
  48. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  49. GRB 231215A: Swift-XRT refined Analysis
  50. GRB 231215A: BOOTES-4/MET optical detection
  51. GRB 231215A: AKO Optical Upper Limit
  52. GRB 231215A: AGILE detection
  53. GRB 231214A: Fermi GBM observation
  54. Konus-Wind detection of GRB 231210B
  55. ATCA observations of GRB 231210B
  56. GRB 231215A: Enhanced Swift-XRT position
  57. Fermi trigger No 724326442: Global MASTER-Net observations report
  58. GRB 231214A: REM optical/NIR upper limits
  59. GRB 231215A: GROWTH-India optical follow-up
  60. GRB 231215A : Nanshan/HMT optical observations
  61. GRB 231215A: AstroSat CZTI detection
  62. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  63. GRB 231214A: Swift-XRT refined Analysis
  64. GRB 231215A: Mondy optical bright afterglow detection
  65. GRB 231214A: AstroSat CZTI detection
  66. GRB 231215C: MASTER OT detection
  67. Swift GRB231215.41: Global MASTER-Net observations report
  68. GRB 231215A: Swift-XRT observations
  69. GRB 231215B: Fermi GBM Final Real-time Localization
  70. GRB 231215A: Swift detection of a burst
  71. GRB 231214A: Fermi-LAT detection
  72. GRB 231214A: Enhanced Swift-XRT position
  73. GRB 231214B: Swift/BAT-GUANO detection of a burst
  74. GRB231214A: BOOTES-6/DPRT optical upper limit
  75. Fermi trigger No 724278269: Global MASTER-Net observations report
  76. Fermi trigger No 724233240: Global MASTER-Net observations report
  77. Swift GRB231214.85: Global MASTER-Net observations report
  78. GRB 231214A: Swift detection of a burst
  79. GRB 231214A: Fermi GBM Final Real-time Localization
  80. GRB 231210B: REM optical/NIR upper limits
  81. IceCube-231211A: Upper limits from a search for additional neutrino events in IceCube
  82. LIGO/Virgo/KAGRA S231213ap: Updated Sky localization
  83. LIGO/Virgo/KAGRA S231213ap: Identification of a GW compact binary merger candidate
  84. Fermi-LAT detection of increased gamma-ray activity of blazar PKS 2047+098, located inside the IceCube-231211A error region
  85. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  86. LIGO/Virgo/KAGRA S231206cc: Upper limits from Swift/BAT-GUANO
  87. LIGO/Virgo/KAGRA S231206ca: Upper limits from Swift/BAT-GUANO
  88. GRB 231212A: GECAM-C detection of a likely short burst
  89. Fermi trigger No 724035412: Global MASTER-Net observations report
  90. GRB 231210B: MeerLICHT afterglow observations
  91. GRB 231210B: Swift-BAT refined analysis
  92. IceCube Alert 231211.03: Global MASTER-Net observations report
  93. IceCube-231202A: No candidates from the Zwicky Transient Facility
  94. GRB 231210B: Swift-XRT refined Analysis
  95. GRB 231210B: Enhanced Swift-XRT position
  96. GRB 231210B: VLT/X-shooter redshift
  97. GRB 231210B: detection of the optical counterpart with the LCOGT 40cm telescope at Sutherland Observatory
  98. Fermi trigger No 723906955: Global MASTER-Net observations report
  99. GRB 231210B: Swift detection of a burst with optical counterpart
  100. Swift GRB231210.90: Global MASTER-Net OT detection

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