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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 231111A: Swift/UVOT Detection
  2. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  3. GRB231115A: Liverpool Telescope imaging
  4. GRB 231115A: NuSTAR Follow-Up Observations
  5. GRB 231115A: Swift/BAT-GUANO detection of a short burst
  6. GRB 231115A: Swift-XRT and Swift-UVOT observations
  7. Fermi GRB 231116A: Global MASTER-Net observations report
  8. Konus-Wind detection of GRB 231115A (a probable Magnetar Giant Flare from M82)
  9. GRB 231115A: AGILE/MCAL upper limits
  10. GRB 231115A: Insight-HXMT/HE detection
  11. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  12. GRB 231116A: Fermi GBM Final Real-time Localization
  13. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  14. GRB 231115A: Gaoyazi/GOT follow-up and archival observations
  15. GRB 231115A / AT2023xvj: Updated GIT analysis
  16. GRB 231115A: archival Chandra X-ray observations
  17. GRB 231115A: Upper limits from a neutrino search with IceCube
  18. GRB 231115A: Kinder observations with Lulin observatory
  19. GRB231115A: GRANDMA Observations
  20. GRB 231115A: GOTO pre-burst limits of AT2023xvj
  21. GRB 231115A: Non-detection in low-latency of gravitational waves with LIGO/Virgo/KAGRA
  22. GRB 231115A: pre-burst ZTF upper limits for GRB optical counterpart candidate
  23. GRB 231106A: TESS identification of candidate optical counterpart
  24. GRB 231115A: MASTER optical observations
  25. GRB 231115A (short): Glowbug gamma-ray detection
  26. GRB 231115A: Fermi Observations of a probable Magnetar Giant Flare from M82
  27. GRB 231115A: archival HST observations
  28. Integral GRB231115.65: Global MASTER-Net observations report
  29. GRB 231115A: GROWTH-India discovery of a potential optical counterpart
  30. GRB 231115A: Swift ToO observations
  31. Fermi GRB 231115A: Global MASTER-Net observations report
  32. GRB 231115A: significance of INTEGRAL localization alignment with M82
  33. GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
  34. GRB 231115A position consistent with M 82 galaxy
  35. GRB 231115A: Fermi GBM Final Real-time Localization
  36. LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
  37. GRB 231111A: Swift-BAT refined analysis
  38. LIGO/Virgo/KAGRA S231113bw: Zwicky Transient Facility observations
  39. LIGO/Virgo/KAGRA S231114n: Updated Sky localization
  40. Fermi GRB 231114A: Global MASTER-Net observations report
  41. GRB 231113A (short): Glowbug gamma-ray detection
  42. GRB 231114A (short): Glowbug gamma-ray detection
  43. LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
  44. GECAM-B observation of a short burst from SGR J1555-5402
  45. GRB 231114A: Fermi GBM Final Localization
  46. LIGO/Virgo S231113bw: upper limits from AGILE/MCAL
  47. LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
  48. SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
  49. LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
  50. GRB 231110A: CALET Gamma-Ray Burst Monitor detection
  51. LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
  52. LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
  53. LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
  54. LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
  55. GRB 231110A: Swift-BAT refined analysis
  56. GRB231111A: MDM 2.4m Hiltner Telescope Observation
  57. GRB 231106A: Glowbug gamma-ray detection
  58. GRB 231111A: Xinglong-2.16m optical observations
  59. GRB 231110A: Swift-UVOT Upper Limits
  60. LIGO/Virgo/KAGRA S231113bb: Identification of a GW compact binary merger candidate
  61. GRB 231111A: Afterglow redshift from OSIRIS+/GTC
  62. GRB 231104A: VZLUSAT-2 detection
  63. GRB 231111A: TNG tentative redshift
  64. GRB 231110A: Glowbug gamma-ray detection
  65. GRB 231110A: AstroSat CZTI detection
  66. GRB 231111A NUTTelA-TAO / BSTI Early Measurements
  67. GRB 231111A: Leavitt Observatory optical observations
  68. GRB231111A: Optical follow-up observations with Mephisto
  69. GRB 231111A: GMG observation (correction)
  70. LIGO/Virgo/KAGRA S231112ag: Retraction of GW compact binary merger candidate
  71. GRB 231111A: GMG observation upper limit
  72. GRB 231106B: GRBAlpha detection
  73. GRB 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
  74. GRB 231110A: Terskol Zeiss-2000 optical upper limit
  75. GRB 231111A: Swift-XRT refined Analysis
  76. GRB 231111A: Mondy optical observations
  77. GRB 231111A: GECAM-C detection of a long burst (correction)
  78. GRB 231110A: GECAM-B detection (correction)
  79. GRB 231111A: Enhanced Swift-XRT position
  80. GRB 231111A: GECAM-C detection of a long burst
  81. GRB 231110A: GECAM detection
  82. GRB 231110A: GOTO optical upper limits
  83. GRB 231110A: SAO RAS optical observations
  84. GRB 231110A: Swift-XRT afterglow detection
  85. GRB231111A: YAHPT Observations
  86. GRB231111A: GIT confirmation of the optical afterglow
  87. GRB 231111A: MASTER OT earlier detection
  88. GRB 231111A: Nanshan/HMT optical observations
  89. GRB 231111A: Swift detection of a burst with an optical counterpart
  90. Swift GRB231111.60: Global MASTER-Net observations report
  91. GRB231110A: WFST Observation and upper limits
  92. Swift GRB231110.89: Global MASTER-Net observations report
  93. GRB 231110A: Swift detection of a burst
  94. LIGO/Virgo/KAGRA S231110g: Updated Sky localization
  95. LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
  96. GRB 231109A: Fermi GBM Final Localization
  97. IceCube-231103A: No candidates from the Zwicky Transient Facility
  98. LIGO/Virgo/KAGRA S231108u: Updated Sky localization
  99. Fermi trigger No 721204446: Global MASTER-Net observations report
  100. Fermi GRB 231108A: Global MASTER-Net observations report

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