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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"

2744 results found.

  1. GRB 230728A: NOT optical observations and possible host galaxy
  2. IceCube-230727A - IceCube observation of a high-energy neutrino candidate track-like event
  3. IceCube-230724A - IceCube observation of a high-energy neutrino candidate track-like event
  4. IceCube-230725A - IceCube observation of a high-energy neutrino candidate track-like event
  5. GRB 230723B: Optical afterglow candidate from CAHA
  6. GRB 230723B: Optical limit from CAHA
  7. Swift Trigger 1178410: possible GRB 230709A
  8. IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
  9. IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event
  10. IceCube-230707A - IceCube observation of a high-energy neutrino candidate track-like event
  11. GRB 230628E - VLT spectroscopic observations
  12. LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
  13. Fermi GBM-230619: A soft subthreshold candidate potentially associated with a subthreshold LIGO/Virgo compact binary merger candidate
  14. ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Swift/UVOT detection
  15. AT2023lcr: Pan-STARRS & ATLAS Observations
  16. ZTF23aaoohpy/AT2023lcr: Keck/LRIS spectroscopy and redshift
  17. LIGO/Virgo/KAGRA S230615az: GOTO candidate counterparts
  18. IceCube-230603A - IceCube observation of a high-energy neutrino candidate track-like event
  19. IceCube-230524A - IceCube observation of a high-energy neutrino candidate track-like event
  20. LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
  21. GRB 230512A: Kitab possible afterglow candidate
  22. IceCube-230511A: IceCube observation of a high-energy neutrino candidate
  23. GRB 230506C: TSHAO possible afterglow candidate
  24. IceCube-230506A: IceCube observation of a high-energy neutrino candidate
  25. GRB 230430A: A short GRB from a neutron star merger
  26. GRB 230420A: Lowell Discovery Telescope Optical Detection
  27. GRB 230420A: Swift-BAT refined analysis
  28. IceCube-230416A: IceCube observation of a high-energy neutrino candidate
  29. GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
  30. GRB 230328B: redshift lower limit estimating
  31. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  32. GRB 230307A: short mininum variability timescale compatible with a merger origin
  33. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  34. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  35. IceCube-230401A: IceCube observation of a high-energy neutrino candidate
  36. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  37. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  38. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  39. GRB 230307A: Possible optical afterglow
  40. Solar Orbiter STIX observation of GRB 230307A
  41. GRB 230307A: GECAM detection of an extremely bright burst
  42. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  43. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  44. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  45. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 230216A: Swift-BAT refined analysis
  47. GRB 230216A: AKO Upper Limit
  48. GRB 230216A: Zadko observatory - Gingin optical observations
  49. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  50. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  51. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  52. GRB 230204B: Swift-XRT afterglow detection
  53. GRB 230205A: OHP/T193 optical observations
  54. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  55. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  56. GRB 221216A: Swift-BAT refined analysis
  57. IceCube-230201A - IceCube observation of a high-energy neutrino candidate track-like event
  58. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  59. IceCube-230122A - IceCube observation of a high-energy neutrino candidate track-like event
  60. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  61. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  62. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  63. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  64. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  65. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  66. IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
  67. IceCube-221124A - IceCube observation of a high-energy neutrino candidate track-like event
  68. GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
  69. GRB 221120A: Swift detection of a likely short burst
  70. IceCube-221104A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 221024A: Swift-BAT refined analysis
  72. GRB 221009A: Analysis of the initial episode using data of GBM/Fermi and SPI-ACS/INTEGRAL
  73. GRB 221016A: z-band upper limit, possible afterglow brightening
  74. GRB 221009A: continued Assy optical afterglow observations, possible SN evidence
  75. MAXI GRB 221006A: Redshifts of the possible host galaxies
  76. Afterglow limits of GRB 221006A from OHP
  77. GRB 221009A: Swift detected transient may be GRB
  78. IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event
  79. IceCube-220907A: Classification of AT2022oyn as a Type Ia supernova
  80. GRB 220921A: MASTER OT inside Fermi-LAT error-box
  81. Fermi-LAT gamma-ray observations of IceCube-220918A and detection of a new gamma-ray source, Fermi J0502.5+0037
  82. IceCube-220918A - IceCube observation of a high-energy neutrino candidate track-like event
  83. IceCube-220907A - IceCube observation of a high-energy neutrino candidate track-like event
  84. GRB 220831A: DECam detection of a possible optical counterpart
  85. IceCube-220822A: Classification of AT2022saw as a Type Ia supernova
  86. IceCube-220822A: One Candidate Counterpart from the Zwicky Transient Facility
  87. IceCube-220822A - IceCube observation of a high-energy neutrino candidate track-like event
  88. GRB 220813A: VLT optical observations and possible host galaxy
  89. Swift/BAT Trigger 1116172 (=GRB 220714A) is not a real astrophysical event
  90. GRB 220714A: Possible Swift detection of a burst
  91. IceCube-220624A: Classification of AT2022nit as a type Ia supernova and AT2021bei as an AGN
  92. IceCube-220629A - IceCube observation of a high-energy neutrino candidate track-like event
  93. Konus-Wind detection of GRB 220627A
  94. IceCube-220624A: One Candidate Counterpart from Swift/XRT follow up observations
  95. Swift XRT observations of WISEA J145820.77+412101.9 / IceCube 220624A
  96. GRB 220627A: Fermi GBM Detection of a possible Lensed or Ultra-long GRB
  97. IceCube-220627A - IceCube observation of a high-energy neutrino candidate track-like event
  98. GRB 220623A: Swift-BAT refined analysis
  99. IceCube-220624A - IceCube observation of a high-energy neutrino candidate track-like event
  100. GRB 220611A: Gemini Ks counterpart detection

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