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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"

5050 results found.

  1. GRB 240124A?: BALROG localization (Fermi Trigger 727752941 / GRB 240124066)
  2. GRB 240123A: Swift-XRT refined Analysis
  3. GRB 240122A: Swift-XRT afterglow detection
  4. Fermi GRB 240115A: Global MASTER-Net observations report
  5. GRB 240112C: Swift/UVOT Detection
  6. GRB 240112C: Swift-XRT refined Analysis
  7. GRB 240112D: Fermi GBM Final Real-time Localization
  8. Fermi trigger No 726774492: Global MASTER-Net observations report
  9. GRB 240112C: Swift detection of a burst with an optical counterpart
  10. GRB 230818A: further radio observations with the VLA
  11. GRB 230812B: further radio observations with the VLA
  12. GRB 240107A: MAXI/GSC detection
  13. IPN triangulation of GRB 240101C (short)
  14. IceCube Alert 240105.52: Global MASTER-Net observations report
  15. GRB 240102A: Swift-XRT refined Analysis
  16. Fermi trigger No 725857207: Global MASTER-Net observations report
  17. GRB 240101A: Terskol Zeiss-2000 optical observations
  18. GRB 240101C: GRBAlpha detection
  19. GRB 240101A: Swift-XRT refined Analysis
  20. GRB 231230A: Swift-XRT refined Analysis
  21. Fermi trigger No 725592555: Global MASTER-Net observations report
  22. Fermi trigger No 725143760: Global MASTER-Net observations report
  23. GRB 231224A: Fermi GBM Final Real-time Localization
  24. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  26. Fermi trigger No 724781422: Global MASTER-Net observations report
  27. GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
  28. GRB 231214B: Fermi GBM observation
  29. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  30. GRB 231216A: Swift-XRT refined analysis correction
  31. GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
  32. Swift GRB231216.77: Global MASTER-Net observations report
  33. GRB 231215A: Swift-XRT refined Analysis
  34. GRB 231214A: Fermi GBM observation
  35. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  36. GRB 231214A: Swift-XRT refined Analysis
  37. GRB 231214A: AstroSat CZTI detection
  38. GRB 231214A: Fermi-LAT detection
  39. GRB 231214A: Swift detection of a burst
  40. GRB 231214A: Fermi GBM Final Real-time Localization
  41. IceCube Alert 231211.03: Global MASTER-Net observations report
  42. GRB 231210B: Swift-XRT refined Analysis
  43. Swift GRB231210.90: Global MASTER-Net observations report
  44. Fermi trigger No 723581802: Global MASTER-Net observations report
  45. GRB 231205B: Swift-XRT refined Analysis
  46. GRB 231205B : MITSuME Akeno optical upper limits
  47. Fermi trigger No 723435916: Global MASTER-Net observations report
  48. Fermi trigger No 723326169: Global MASTER-Net observations report
  49. GRB 231129C: PROMPT optical upper limits for the MAXI/GSC X-ray counterpart and the MASTER afterglow candidate
  50. GRB 231128A: VZLUSAT-2 detection
  51. GRB 231129A : MITSuME Akeno optical upper limits
  52. GRB 231129C: MAXI/GSC detection
  53. GRB 231129A: Swift-XRT refined Analysis
  54. Fermi trigger No 722977823: Global MASTER-Net observations report
  55. IceCube-231125A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB 231124A: GRBAlpha detection
  57. Fermi trigger No 722653947: Global MASTER-Net observations report
  58. Fermi trigger No 722507896: Global MASTER-Net observations report
  59. GRB 231124A: Glowbug gamma-ray detection
  60. Fermi trigger No 722462310: Global MASTER-Net observations report
  61. GRB 231124A: CALET Gamma-Ray Burst Monitor detection
  62. GRB 231124A: Fermi GBM Final Real-time Localization
  63. Fermi trigger No 722400249: Global MASTER-Net observations report
  64. GRB 231117A : MITSuME Akeno optical afterglow candidate detection
  65. GRB 231118A: MeerLICHT afterglow detection
  66. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  67. GRB 231117A : MITSuME Akeno optical upper limits
  68. Fermi GRB 231116A: Global MASTER-Net observations report
  69. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  70. GRB 231111A: Swift-XRT refined Analysis
  71. IceCube-231103A: No candidates from the Zwicky Transient Facility
  72. Fermi trigger No 721204446: Global MASTER-Net observations report
  73. Fermi GRB 231108A: Global MASTER-Net observations report
  74. GRB 231104A: 3.6m DOT optical upper limit
  75. Fermi GRB 231103A: Global MASTER-Net observations report
  76. GRB 231104A: AstroSat CZTI detection
  77. GRB 231104A: Swift-XRT refined Analysis
  78. IceCube Alert 231103.39: Global MASTER-Net observations report
  79. Fermi trigger No 720498201: Global MASTER-Net observations report
  80. IceCube-231027A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 231024A: AKO Optical Counterpart Candidate
  82. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  83. IceCube Alert 231027.18: Global MASTER-Net observations report
  84. LIGO/Virgo/KAGRA S231025t: Global MASTER-Net observations report
  85. LIGO/Virgo/KAGRA S231025a: Global MASTER-Net observations report
  86. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  87. GRB 231024A: Fermi GBM Observation
  88. GRB 231024A: LCOGT and ZTF detections of the GOTO optical counterpart candidate
  89. GRB 231024A: GOTO optical counterpart candidate
  90. GRB 231024A: Fermi GBM Final Localization
  91. Fermi trigger No 719846439: Global MASTER-Net observations report
  92. The photometry of the transient in Messier 31 field: GMG observation
  93. GRB 231012A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705709044)
  94. Fermi GRB 231019A: Global MASTER-Net observations report
  95. IPN triangulation of GRB 231018A
  96. GRB 231017A: JinShan optical upper limit
  97. GRB 231015A: AstroSat CZTI detection
  98. (correction) Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field
  99. Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field.
  100. NuEm-230927A: Swift-XRT follow-up

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