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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"

2707 results found.

  1. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  2. GRB 230307A: Possible optical afterglow
  3. Solar Orbiter STIX observation of GRB 230307A
  4. GRB 230307A: GECAM detection of an extremely bright burst
  5. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  6. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  7. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  8. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  9. GRB 230216A: Swift-BAT refined analysis
  10. GRB 230216A: AKO Upper Limit
  11. GRB 230216A: Zadko observatory - Gingin optical observations
  12. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  13. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  14. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  15. GRB 230204B: Swift-XRT afterglow detection
  16. GRB 230205A: OHP/T193 optical observations
  17. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  18. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  19. GRB 221216A: Swift-BAT refined analysis
  20. IceCube-230201A - IceCube observation of a high-energy neutrino candidate track-like event
  21. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  22. IceCube-230122A - IceCube observation of a high-energy neutrino candidate track-like event
  23. IceCube-230112A - IceCube observation of a high-energy neutrino candidate track-like event
  24. IceCube-221229A - IceCube observation of a high-energy neutrino candidate track-like event
  25. ZTF22acaruqr/AT2022adzb: Neil Gehrels Swift Observatory X-ray detection
  26. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  27. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  28. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  29. IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
  30. IceCube-221124A - IceCube observation of a high-energy neutrino candidate track-like event
  31. GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
  32. GRB 221120A: Swift detection of a likely short burst
  33. IceCube-221104A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 221024A: Swift-BAT refined analysis
  35. GRB 221009A: Analysis of the initial episode using data of GBM/Fermi and SPI-ACS/INTEGRAL
  36. GRB 221016A: z-band upper limit, possible afterglow brightening
  37. GRB 221009A: continued Assy optical afterglow observations, possible SN evidence
  38. MAXI GRB 221006A: Redshifts of the possible host galaxies
  39. Afterglow limits of GRB 221006A from OHP
  40. GRB 221009A: Swift detected transient may be GRB
  41. IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event
  42. IceCube-220907A: Classification of AT2022oyn as a Type Ia supernova
  43. GRB 220921A: MASTER OT inside Fermi-LAT error-box
  44. Fermi-LAT gamma-ray observations of IceCube-220918A and detection of a new gamma-ray source, Fermi J0502.5+0037
  45. IceCube-220918A - IceCube observation of a high-energy neutrino candidate track-like event
  46. IceCube-220907A - IceCube observation of a high-energy neutrino candidate track-like event
  47. GRB 220831A: DECam detection of a possible optical counterpart
  48. IceCube-220822A: Classification of AT2022saw as a Type Ia supernova
  49. IceCube-220822A: One Candidate Counterpart from the Zwicky Transient Facility
  50. IceCube-220822A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 220813A: VLT optical observations and possible host galaxy
  52. Swift/BAT Trigger 1116172 (=GRB 220714A) is not a real astrophysical event
  53. GRB 220714A: Possible Swift detection of a burst
  54. IceCube-220624A: Classification of AT2022nit as a type Ia supernova and AT2021bei as an AGN
  55. IceCube-220629A - IceCube observation of a high-energy neutrino candidate track-like event
  56. Konus-Wind detection of GRB 220627A
  57. IceCube-220624A: One Candidate Counterpart from Swift/XRT follow up observations
  58. Swift XRT observations of WISEA J145820.77+412101.9 / IceCube 220624A
  59. GRB 220627A: Fermi GBM Detection of a possible Lensed or Ultra-long GRB
  60. IceCube-220627A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 220623A: Swift-BAT refined analysis
  62. IceCube-220624A - IceCube observation of a high-energy neutrino candidate track-like event
  63. GRB 220611A: Gemini Ks counterpart detection
  64. GRB 220611A: Swift-BAT refined analysis
  65. GRB 220527A: VLT/X-shooter spectroscopic redshift
  66. GRB 220521A: classification and detection by SPI-ACS/INTEGRAL
  67. IceCube-220524A - IceCube observation of a high-energy neutrino candidate track-like event
  68. IceCube-220513A - IceCube observation of a high-energy neutrino candidate track-like event
  69. IceCube-220509A - IceCube observation of a high-energy neutrino candidate track-like event
  70. IceCube-220501A - IceCube observation of a high-energy neutrino candidate track-like event
  71. IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
  72. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  73. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 220408A: redshift lower limit estimating
  75. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  76. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  77. GRB 220403B: Swift detection of a burst with an optical counterpart
  78. IceCube-220317A - IceCube observation of a high-energy neutrino candidate track-like event
  79. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
  80. CALET Gamma-Ray Burst Monitor detection of GRB 220308A and its possible precursor
  81. GRB 220306B: Mondy optical observations, confirmation afterglow candidate
  82. GRB 220306B: AbAO optical observations, possible afterglow candidate
  83. IceCube-220306A - IceCube observation of a high-energy neutrino candidate track-like event
  84. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  85. Tev Blazar as possible optical counterpart of the high-energy neutrino IceCube-220303A
  86. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  87. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  88. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  89. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  90. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  91. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  92. GRB 220211A: redshift lower limit estimating
  93. GRB 210919A: SPI-ACS/INTEGRAL observation and evaluation of Ep
  94. IceCube-220205B - IceCube observation of a high-energy neutrino candidate track-like event
  95. IceCube-220205A - IceCube observation of a high-energy neutrino candidate track-like event
  96. IceCube-220202A: IceCube observation of a high-energy neutrino candidate track-like event
  97. Swift currently in safe hold with science slews disabled
  98. IceCube-220115A - IceCube observation of a high-energy neutrino candidate track-like event
  99. Konus-Wind detection of GRB 220101A (correction to GCN 31433)
  100. GRB 211227A: A possible short GRB with extended emission at z = 0.228?

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