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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 231115A: optical observations from INAF observatories
  2. GRB 231117A : MITSuME Akeno optical upper limits
  3. GRB 231117A: AGILE detection of a bright short burst
  4. GRB 231117A: Enhanced Swift-XRT position
  5. GRB 231117A: GOTO optical upper limits
  6. GRB 231117A: AstroSat CZTI detection of a bright short burst
  7. GRB 231117A: Swift detection of a bright short burst
  8. GRB 231115A: Non-detection of radio emission with CHIME/FRB
  9. GRB 231111A: Swift/UVOT Detection
  10. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  11. GRB231115A: Liverpool Telescope imaging
  12. GRB 231115A: NuSTAR Follow-Up Observations
  13. GRB 231115A: Swift/BAT-GUANO detection of a short burst
  14. GRB 231115A: Swift-XRT and Swift-UVOT observations
  15. Fermi GRB 231116A: Global MASTER-Net observations report
  16. Konus-Wind detection of GRB 231115A (a probable Magnetar Giant Flare from M82)
  17. GRB 231115A: AGILE/MCAL upper limits
  18. GRB 231115A: Insight-HXMT/HE detection
  19. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  20. GRB 231116A: Fermi GBM Final Real-time Localization
  21. GRB 231115A : MITSuME Akeno and Okayama optical upper limits
  22. GRB 231115A: Gaoyazi/GOT follow-up and archival observations
  23. GRB 231115A / AT2023xvj: Updated GIT analysis
  24. GRB 231115A: archival Chandra X-ray observations
  25. GRB 231115A: Upper limits from a neutrino search with IceCube
  26. GRB 231115A: Kinder observations with Lulin observatory
  27. GRB231115A: GRANDMA Observations
  28. GRB 231115A: GOTO pre-burst limits of AT2023xvj
  29. GRB 231115A: Non-detection in low-latency of gravitational waves with LIGO/Virgo/KAGRA
  30. GRB 231115A: pre-burst ZTF upper limits for GRB optical counterpart candidate
  31. GRB 231106A: TESS identification of candidate optical counterpart
  32. GRB 231115A: MASTER optical observations
  33. GRB 231115A (short): Glowbug gamma-ray detection
  34. GRB 231115A: Fermi Observations of a probable Magnetar Giant Flare from M82
  35. GRB 231115A: archival HST observations
  36. Integral GRB231115.65: Global MASTER-Net observations report
  37. GRB 231115A: GROWTH-India discovery of a potential optical counterpart
  38. GRB 231115A: Swift ToO observations
  39. Fermi GRB 231115A: Global MASTER-Net observations report
  40. GRB 231115A: significance of INTEGRAL localization alignment with M82
  41. GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
  42. GRB 231115A position consistent with M 82 galaxy
  43. GRB 231115A: Fermi GBM Final Real-time Localization
  44. LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
  45. GRB 231111A: Swift-BAT refined analysis
  46. LIGO/Virgo/KAGRA S231113bw: Zwicky Transient Facility observations
  47. LIGO/Virgo/KAGRA S231114n: Updated Sky localization
  48. Fermi GRB 231114A: Global MASTER-Net observations report
  49. GRB 231113A (short): Glowbug gamma-ray detection
  50. GRB 231114A (short): Glowbug gamma-ray detection
  51. LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
  52. GECAM-B observation of a short burst from SGR J1555-5402
  53. GRB 231114A: Fermi GBM Final Localization
  54. LIGO/Virgo S231113bw: upper limits from AGILE/MCAL
  55. LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
  56. SGRJ1555-5402: Swift/BAT-GUANO arcminute localization of a SGR flare
  57. LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
  58. GRB 231110A: CALET Gamma-Ray Burst Monitor detection
  59. LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
  60. LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
  61. LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
  62. LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
  63. GRB 231110A: Swift-BAT refined analysis
  64. GRB231111A: MDM 2.4m Hiltner Telescope Observation
  65. GRB 231106A: Glowbug gamma-ray detection
  66. GRB 231111A: Xinglong-2.16m optical observations
  67. GRB 231110A: Swift-UVOT Upper Limits
  68. LIGO/Virgo/KAGRA S231113bb: Identification of a GW compact binary merger candidate
  69. GRB 231111A: Afterglow redshift from OSIRIS+/GTC
  70. GRB 231104A: VZLUSAT-2 detection
  71. GRB 231111A: TNG tentative redshift
  72. GRB 231110A: Glowbug gamma-ray detection
  73. GRB 231110A: AstroSat CZTI detection
  74. GRB 231111A NUTTelA-TAO / BSTI Early Measurements
  75. GRB 231111A: Leavitt Observatory optical observations
  76. GRB231111A: Optical follow-up observations with Mephisto
  77. GRB 231111A: GMG observation (correction)
  78. LIGO/Virgo/KAGRA S231112ag: Retraction of GW compact binary merger candidate
  79. GRB 231111A: GMG observation upper limit
  80. GRB 231106B: GRBAlpha detection
  81. GRB 231111A: Osservatorio Astronomico "Nastro Verde" optical observations with detection of an optical counterpart
  82. GRB 231110A: Terskol Zeiss-2000 optical upper limit
  83. GRB 231111A: Swift-XRT refined Analysis
  84. GRB 231111A: Mondy optical observations
  85. GRB 231111A: GECAM-C detection of a long burst (correction)
  86. GRB 231110A: GECAM-B detection (correction)
  87. GRB 231111A: Enhanced Swift-XRT position
  88. GRB 231111A: GECAM-C detection of a long burst
  89. GRB 231110A: GECAM detection
  90. GRB 231110A: GOTO optical upper limits
  91. GRB 231110A: SAO RAS optical observations
  92. GRB 231110A: Swift-XRT afterglow detection
  93. GRB231111A: YAHPT Observations
  94. GRB231111A: GIT confirmation of the optical afterglow
  95. GRB 231111A: MASTER OT earlier detection
  96. GRB 231111A: Nanshan/HMT optical observations
  97. GRB 231111A: Swift detection of a burst with an optical counterpart
  98. Swift GRB231111.60: Global MASTER-Net observations report
  99. GRB231110A: WFST Observation and upper limits
  100. Swift GRB231110.89: Global MASTER-Net observations report

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