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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"

21458 results found.

  1. 231118A: Swift-UVOT Detection
  2. GRB231117A: Swift-UVOT detection
  3. GRB 231118A: Fermi GBM observation
  4. GRB 231117A: Swift-XRT refined Analysis
  5. GRB 231118A: Swift-XRT refined Analysis
  6. GRB 231118A: MeerLICHT afterglow detection
  7. GRB 231118A: VLT/X-shooter redshift
  8. GRB 231117A: MAAO 0.7-m telescope optical upper limit
  9. GRB 231117A: GECAM-C detection
  10. GRB 231118A: AstroSat CZTI detection
  11. GRB 231115A: Upper limit from CALET Gamma-Ray Burst Monitor
  12. GRB 231118A: Las Cumbres optical detection
  13. GRB 231118A: LCOGT Optical Observations
  14. GRB 231118A: MASTER OT observation
  15. Swift GRB231118.72: Global MASTER-Net observations report
  16. GRB 231118A: Enhanced Swift-XRT position
  17. GRB 231117A: Kinder observations with Lulin observatory for AT 2023yba without fading in r band
  18. GRB 231118A: Swift-XRT position
  19. GRB 231118A: Skynet Optical Afterglow Discovery
  20. GRB 231118A: Swift detection of a burst
  21. GRB 231117A: ATCA detection of a radio counterpart
  22. GRB 231117A: GRBAlpha detection
  23. GRB 231117A: GIT optical follow-up
  24. GRB 231117A: Keck observations indicate presence of optical afterglow in z~0.3-0.5 galaxy
  25. GRB 231117A: REM optical and NIR early-time observations
  26. GRB 231117A: AKO Optical Upper Limit
  27. GRB 231117A: afterglow candidate detection from Kinder observations with Lulin observatory
  28. Swift GRB 231117A: Global MASTER-Net observations report
  29. GRB 231117A (short): Glowbug gamma-ray detection
  30. GRB 231117A: ATLAS non-detection of an optical counterpart
  31. Konus-Wind detection of GRB 231117A (short/hard)
  32. GRB 231115A: optical observations from INAF observatories
  33. GRB 231117A : MITSuME Akeno optical upper limits
  34. GRB 231117A: AGILE detection of a bright short burst
  35. GRB 231117A: Enhanced Swift-XRT position
  36. GRB 231117A: GOTO optical upper limits
  37. GRB 231117A: AstroSat CZTI detection of a bright short burst
  38. GRB 231117A: Swift detection of a bright short burst
  39. GRB 231111A: Swift/UVOT Detection
  40. GRB 231115A: Swift/BAT-GUANO detection of a short burst
  41. GRB 231115A: Swift-XRT and Swift-UVOT observations
  42. GRB 231115A: Swift ToO observations
  43. GRB 231111A: Swift-BAT refined analysis
  44. GECAM-B observation of a short burst from SGR J1555-5402
  45. SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
  46. GRB 231110A: CALET Gamma-Ray Burst Monitor detection
  47. GRB 231110A: Swift-BAT refined analysis
  48. GRB231111A: MDM 2.4m Hiltner Telescope Observation
  49. GRB 231111A: Xinglong-2.16m optical observations
  50. GRB 231110A: Swift-UVOT Upper Limits
  51. GRB 231104A: VZLUSAT-2 detection
  52. GRB 231110A: Glowbug gamma-ray detection
  53. GRB 231110A: AstroSat CZTI detection
  54. GRB 231111A NUTTelA-TAO / BSTI Early Measurements
  55. GRB 231111A: Leavitt Observatory optical observations
  56. GRB231111A: Optical follow-up observations with Mephisto
  57. GRB 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
  58. GRB 231110A: Terskol Zeiss-2000 optical upper limit
  59. GRB 231111A: Swift-XRT refined Analysis
  60. GRB 231111A: Mondy optical observations
  61. GRB 231111A: GECAM-C detection of a long burst (correction)
  62. GRB 231110A: GECAM-B detection (correction)
  63. GRB 231111A: Enhanced Swift-XRT position
  64. GRB 231111A: GECAM-C detection of a long burst
  65. GRB 231110A: GECAM detection
  66. GRB 231110A: SAO RAS optical observations
  67. GRB 231110A: Swift-XRT afterglow detection
  68. GRB231111A: YAHPT Observations
  69. GRB231111A: GIT confirmation of the optical afterglow
  70. GRB 231111A: MASTER OT earlier detection
  71. GRB 231111A: Nanshan/HMT optical observations
  72. GRB 231111A: Swift detection of a burst with an optical counterpart
  73. Swift GRB231111.60: Global MASTER-Net observations report
  74. GRB231110A: WFST Observation and upper limits
  75. Swift GRB231110.89: Global MASTER-Net observations report
  76. GRB 231110A: Swift detection of a burst
  77. GRB 231104A: Swift-BAT refined analysis
  78. GRB 231104A: FRAM-ORM optical limit
  79. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  80. GRB 231104A: Wendelstein Optical/Infrared Observations
  81. GRB 231104A: NuSTAR Observation of the prompt emission
  82. GRB 231104A: 3.6m DOT optical upper limit
  83. GRB 231104A: NOT upper limit
  84. GRB 231104A: Fermi GBM Observation
  85. GRB 231104A: AKO Upper Limit
  86. GRB 231104A: AstroSat CZTI detection
  87. GRB 231104A: Swift-XRT refined Analysis
  88. GRB 231104A: Fermi-LAT detection
  89. GRB 231104A: Swift/UVOT Upper Limits
  90. GRB 231104A: Enhanced Swift-XRT position
  91. GRB231104A: LCOGT Optical Upper Limits
  92. GRB 231104A: Swift detection of a bright burst
  93. Swift GRB231104.07: Global MASTER-Net observations report
  94. New Swift-BAT/GUANO and IceCube Notices Available via GCN Kafka
  95. IPN triangulation of GRB 231020A
  96. GRB 231028A: Swift-BAT refined analysis
  97. LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
  98. GRB 231028A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 231028A: AstroSat CZTI detection
  100. GRB 231028A: Glowbug gamma-ray detection

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