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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"

21577 results found.

  1. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  2. GRB 240122A: GOTO optical counterpart candidate
  3. GRB 240122A: Tiled Swift observations
  4. GRB 240118A: Mondy optical observations
  5. GRB 240118A: Swift-XRT afterglow detection
  6. Fermi GRB 240119A: Global MASTER-Net observations report
  7. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  8. GRB 240118C: Swift/BAT-GUANO detection of a burst
  9. GRB 240118A: Swift ToO observations
  10. Fermi GRB 240118B: Global MASTER-Net observations report
  11. GRB 240118A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  12. Konus-Wind detection of GRB 240118A
  13. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A
  14. LAT GRB240118.08: Global MASTER-Net observations report
  15. GRB 240115A: Swift/BAT-GUANO detection of a short burst
  16. Swift Triggers 1209369 and 1209370 are not astrophysical events
  17. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  18. Integral GRB240115.70: Global MASTER-Net observations report
  19. Fermi GRB 240115B: Global MASTER-Net observations report
  20. Fermi GRB 240115A: Global MASTER-Net observations report
  21. GRB 240112C: Swift/UVOT Detection
  22. Fermi trigger No 726773850: Global MASTER-Net observations report
  23. GRB 240112C: SAO RAS optical observations
  24. Fermi GRB 240112D: Global MASTER-Net observations report
  25. Fermi trigger No 726774492: Global MASTER-Net observations report
  26. Swift GRB 240112C: Global MASTER-Net observations report
  27. Fermi GRB 240112B: Global MASTER-Net observations report
  28. Fermi-LAT detection of increased gamma-ray activity of blazar PKS 0446+11, located inside the IceCube-240105A error region
  29. GRB 231214A: ATCA Radio Upper Limits
  30. IceCube-240105A: Three candidates from the Zwicky Transient Facility
  31. GRB 231215A: radio detection with the VLA
  32. GRB 230818A: further radio observations with the VLA
  33. GRB 230812B: further radio observations with the VLA
  34. Swift GRB240109.17: Global MASTER-Net observations report
  35. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  36. IceCube-240105A: JCMT SCUBA2 Detection of Two Bright Submillimeter Sources
  37. Fermi trigger No 726347794: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  39. Fermi trigger No 726194053: Global MASTER-Net observations report
  40. IceCube Alert 240105.52: Global MASTER-Net observations report
  41. GRB 240101A: 1.3m DFOT optical observations
  42. GRB 240102A: 1.3m DFOT optical upper limit
  43. GRB 240101B: 1.3m DFOT optical upper limit
  44. GRB 240101C: Swift/BAT-GUANO detection of a short burst
  45. GRB 231220A: Swift-UVOT upper limit
  46. GRB 240102A: Swift/UVOT Upper Limits
  47. Fermi trigger No 725857207: Global MASTER-Net observations report
  48. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  49. GRB 240101A: Terskol Zeiss-2000 optical observations
  50. GRB 240101B: Swift/UVOT Upper Limits
  51. GRB 240101A: Swift/UVOT Upper Limits
  52. Swift GRB240101.85: Global MASTER-Net observations report
  53. Fermi trigger No 725806648: Global MASTER-Net observations report
  54. GRB 231230A: GOTO optical upper limits
  55. GRB 231230A: Swift/UVOT Upper Limits
  56. GRB 231230A: NOT optical upper limits
  57. Fermi trigger No 725592555: Global MASTER-Net observations report
  58. Swift GRB231230.06: Global MASTER-Net observations report
  59. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  60. Fermi trigger No 725143760: Global MASTER-Net observations report
  61. GRB 231222B: Swift-XRT afterglow detection
  62. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  63. Fermi trigger No 724921799: Global MASTER-Net observations report
  64. LAT GRB231222.31: Global MASTER-Net observations report
  65. GRB 231222A: Tiled Swift observations
  66. IceCube-231211A: GRANDMA observations of PKS2047+098
  67. GRB 231220A: Swift-XRT follow-up observations
  68. GRB 231220A: Swift ToO observations
  69. GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
  70. Fermi trigger No 724781422: Global MASTER-Net observations report
  71. GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
  72. Fermi trigger No 724698747: Global MASTER-Net observations report
  73. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  74. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  75. GRB 231215A: AMI-LA radio detection
  76. GRB 231216A: Nanshan/HMT optical upper limit
  77. GRB 231216A: Osservatorio Astronomico Nastro Verde upper limit
  78. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  79. GRB 231216A: REM NIR upper limits
  80. GRB 231216A: Swift/UVOT Upper Limits
  81. GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
  82. GRB 231216A: GIT optical upper limit
  83. GRB 231216A: NOT optical upper limits
  84. Swift GRB231216.77: Global MASTER-Net observations report
  85. Konus-Wind detection of GRB 231215A
  86. GRB 231215A: optical afterglow detection from the INAF Asiago Observatory
  87. GRB 231215A: NOT optical observations
  88. GRB 231214A: Swift/UVOT Upper Limits
  89. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  90. GRB 231215A : OHP/T193 optical afterglow detection
  91. GRB 231215A: Swift/UVOT Detection
  92. ATCA observations of GRB 231210B
  93. Fermi trigger No 724326442: Global MASTER-Net observations report
  94. GRB 231214A: REM optical/NIR upper limits
  95. GRB 231215A: GROWTH-India optical follow-up
  96. GRB 231215A : Nanshan/HMT optical observations
  97. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  98. GRB 231215C: MASTER OT detection
  99. Swift GRB231215.41: Global MASTER-Net observations report
  100. GRB 231215A: Swift-XRT observations

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