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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').

2445 results found.

  1. GRB 220611A: Gemini Ks counterpart detection
  2. GRB 220611A: Swift-BAT refined analysis
  3. GRB 220527A: VLT/X-shooter spectroscopic redshift
  4. GRB 220521A: classification and detection by SPI-ACS/INTEGRAL
  5. IceCube-220524A - IceCube observation of a high-energy neutrino candidate track-like event
  6. IceCube-220513A - IceCube observation of a high-energy neutrino candidate track-like event
  7. IceCube-220509A - IceCube observation of a high-energy neutrino candidate track-like event
  8. IceCube-220501A - IceCube observation of a high-energy neutrino candidate track-like event
  9. IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
  10. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  11. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  12. GRB 220408A: redshift lower limit estimating
  13. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  14. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  15. GRB 220403B: Swift detection of a burst with an optical counterpart
  16. IceCube-220317A - IceCube observation of a high-energy neutrino candidate track-like event
  17. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
  18. CALET Gamma-Ray Burst Monitor detection of GRB 220308A and its possible precursor
  19. GRB 220306B: Mondy optical observations, confirmation afterglow candidate
  20. GRB 220306B: AbAO optical observations, possible afterglow candidate
  21. IceCube-220306A - IceCube observation of a high-energy neutrino candidate track-like event
  22. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  23. Tev Blazar as possible optical counterpart of the high-energy neutrino IceCube-220303A
  24. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  25. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  26. IceCube Alert 220220.60:NuEm-220220A: MASTER optical possible counterpart
  27. ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
  28. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  29. ZTF22aaajecp/AT2022cmc: Keck DEIMOS Redshift
  30. GRB 220211A: redshift lower limit estimating
  31. GRB 210919A: SPI-ACS/INTEGRAL observation and evaluation of Ep
  32. IceCube-220205B - IceCube observation of a high-energy neutrino candidate track-like event
  33. IceCube-220205A - IceCube observation of a high-energy neutrino candidate track-like event
  34. IceCube-220202A: IceCube observation of a high-energy neutrino candidate track-like event
  35. Swift currently in safe hold with science slews disabled
  36. IceCube-220115A - IceCube observation of a high-energy neutrino candidate track-like event
  37. Konus-Wind detection of GRB 220101A (correction to GCN 31433)
  38. GRB 211227A: A possible short GRB with extended emission at z = 0.228?
  39. IceCube-211216B - IceCube observation of a high-energy neutrino candidate track-like event
  40. IceCube-211216A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 211211A - Gemini K-band detection
  42. GRB 211211A: redshift estimation and SPI-ACS/INTEGRAL detection
  43. GRB 211130A: MeerLICHT identification of possible afterglow candidate
  44. IceCube-211208A - IceCube observation of a high-energy neutrino candidate track-like event
  45. Swift Trigger 1086826 (possible GRB 211203A) is likely not an astrophysical event
  46. GRB 211106A: HST Observations
  47. IceCube-211125A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  48. IceCube-211125A: IceCube observation of a high-energy neutrino candidate track-like event
  49. IceCube-211123A - IceCube observation of a high-energy neutrino candidate track-like event
  50. GRB 211023A: optical observations and photometric evidence of supernova
  51. IceCube-211117A : IceCube observation of a high-energy neutrino candidate track-like event
  52. IceCube-211116A : IceCube observation of a high-energy neutrino candidate track-like event
  53. GRB 211023A: BTA spectroscopic redshift
  54. GRB 211023A: continued 1.3m DFOT Optical Observations and possible jet break
  55. GRB 211024A: Possible afterglow candidate from GIT
  56. Possible Short GRB 211023B: CAHA 2.2m Detection
  57. GRB 211023B: TSHAO optical observation
  58. IceCube-211023A - IceCube observation of a high-energy neutrino candidate track-like event
  59. IceCube-210922A: Hard X-ray flux limit for JCMT/SCUBA2 source from NuSTAR observations
  60. Swift trigger 1078701: MITSuME Akeno optical upper limits
  61. Swift Trigger 1078701: Mondy, CrAO, AbAO observations, possible optical counterpart
  62. GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
  63. IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 210912A: BOOTES-5/JGT optical afterglow candidate (Correction to GCNC 30823)
  65. IceCube-210811A - IceCube observation of a high-energy neutrino candidate track-like event
  66. GRB 210802A: Further Swift/XRT observation and afterglow confirmation
  67. GRB 210807A: correction to the GCN Circ. #30614 Assy optical observations
  68. GRB 210802A: BOOTES-2/TELMA optical upper limit
  69. IceCube-210730A - IceCube observation of a high-energy neutrino candidate track-like event
  70. GRB 210726A: OSIRIS/GTC observations
  71. GRB 210726A: Deep CAHA 2.2m limit
  72. IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
  73. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  74. GRB 210704A: Gemini-North Infrared Source Detection
  75. GRB 210708B: Swift-BAT refined analysis
  76. IceCube-210629A - Spectroscopic observation of AT2021osi
  77. GRB 210708B: Swift detection of a possible burst
  78. GRB 210704A: possible local hosts
  79. GRB 210702A: BOOTES-3/YA optical counterpart observations
  80. GRB 210702A: Swift/UVOT redshift
  81. IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
  82. GRB 210626A: Swift/XRT afterglow confirmation
  83. GRB 210618A: 1.5m OSN optical upper limit
  84. GRB 210619B: Ondrejov D50 detection
  85. GRB 210610A: 1.5m OSN optical observation
  86. GRB 210610B: BOOTES-2/TELMA optical observation
  87. IceCube-210608A: IceCube observation of a high-energy neutrino candidate track-like event
  88. GRB 210607A/MAXI J1733-222: MAXI/GSC detection
  89. GRB210413B: further Swift-XRT observations
  90. GRB 210517A: KCT optical upper limit
  91. IceCube-210516A - IceCube observation of a high-energy neutrino candidate track-like event
  92. IceCube-210510A - IceCube observation of a high-energy neutrino candidate track-like event
  93. Fermi-LAT Gamma-ray Observations of IceCube-210503A and detection of a new gamma-ray source, Fermi J0931.9+3633
  94. IceCube-210503A: IceCube observation of a high-energy neutrino candidate event
  95. GRB 210506A: Swift/BAT-GUANO detection and possible arcminute localization of a short hard burst
  96. GRB 210411C: A very significant early X-ray afterglow
  97. GRB 210410A: A twin of short GRB 090510 with complementary observations
  98. GRB 210410A: RATIR Optical and NIR Observations
  99. GRB 210207B: Prompt and very late time observations with HCT.
  100. GRB 210323A: Gemini-North Optical Source Detection

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