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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"

7301 results found.

  1. Zwicky Transient Facility discovery of ZTF20abtxwfx/AT2020sev, a fast optical transient and candidate afterglow
  2. GRB 200826A: VLA Detection at 6 GHz
  3. GRB200826A: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi Short GRB (Trigger 620108997)
  4. GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
  5. GRB 200826A: Tiled Swift observations
  6. Swift Trigger 992444: a possible GRB 200821A
  7. GRB 200819A: Swift detection of a burst
  8. Swift trigger 990358 is not an astrophysical source
  9. Swift trigger 989458 is likely not an astrophysical source
  10. GRB 200809B: Swift ToO observations
  11. IceCube-200806A: Upper limits from Fermi-GBM Observations
  12. GRB 200806A: Swift detection of a burst
  13. IceCube-200806A: IceCube observation of a high-energy neutrino candidate event
  14. GRB 200803A: Fermi GBM detection
  15. GRB 200803A: Tiled Swift observations
  16. Konus-Wind detection of GRB 200729A
  17. Fermi-GBM Sub-Threshold candidate for GRB 200729A
  18. GRB 200729A: NOT optical upper limits
  19. GRB 200729A: Swift detection of a burst
  20. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  21. GRB 200723A: Swift ToO observations
  22. GRB 200723A: GOTO candidate afterglow and host galaxy
  23. AMON IC_HAWC 170720: No Neutrino Counterpart detected with ANTARES
  24. GRB 200716C: Optical observations from HCT
  25. GRB 200522A: HST NIR counterpart confirmation
  26. GRB 200716C: Swift detection of a burst with an optical counterpart
  27. GRB 200715A: Swift ToO observations
  28. GRB 200714E: Swift ToO observations
  29. GRB 200522A: Candidate Optical/nIR Counterpart from Gemini and HST Imaging
  30. GRB 200713A: Swift detection of a burst
  31. GRB 200711A: KAIT Optical Upper Limit
  32. GRB 200711A: Swift detection of a burst
  33. GRB 200709B/HAWC-200907A: Swift-XRT further observations
  34. HAWC-200907A: No Neutrino Counterpart detected with ANTARES
  35. GRB 200709B: Tiled Swift observations
  36. Trigger 980513: Swift detection of SGR Swift J1818.0-1607
  37. GRB 200630A: Swift detection of a burst
  38. GRB 200623A: Further MMTCam Observations of XRT Source #3
  39. GRB 200623A: LBT optical observations
  40. GRB 200625A: Swift ToO observations
  41. GRB 200623A: Swift/UVOT Upper Limits
  42. GRB 200623A: OAJ deep multi-color imaging, XRT #2 is pre-detected
  43. GRB 200623A: TNG optical observations
  44. GRB 200623A: AbAO afterglow candidate within XRT #2
  45. GRB 200623A: Swift ToO observations
  46. IceCube-200620A: MASTER previous detection of ZTF20abgvabi/AT2020ncr
  47. IceCube-200620A: not observable by Fermi-GBM
  48. IceCube-200620A: One Candidate Counterpart from the Zwicky Transient Facility
  49. IceCube-200620A: No ANTARES neutrino counterpart
  50. IceCube-200620A - IceCube observation of a high-energy neutrino candidate track-like event
  51. LIGO/Virgo MS200618aq: Retraction of a test binary neutron star candidate
  52. LIGO/Virgo MS200619bf: Retraction of a test binary neutron star candidate
  53. LIGO/Virgo MS200618bx: Retraction of a test binary neutron star candidate
  54. LIGO/Virgo MS200618bq: Retraction of a test binary neutron star candidate
  55. IceCube-200530A - SN2020lls likely unrelated
  56. LIGO/Virgo MS200614ct: Identification of a test binary black hole candidate
  57. Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
  58. LIGO/Virgo MS200615ce: Identification of a test binary black hole candidate
  59. LIGO/Virgo MS200614bz: Test Identification of a binary neutron star candidate
  60. IceCube-200615A: Upper limits from Fermi-GBM Observations
  61. IceCube-200614A: not observable by Fermi-GBM
  62. LIGO/Virgo MS200615h: Retraction of a test binary neutron star candidate
  63. IceCube-200615A: IceCube observation of a high-energy neutrino candidate event
  64. IceCube-200614A - IceCube observation of a high-energy neutrino candidate track-like event
  65. GRB 200613A: Kitab and AbAO optical afterglow observations, host galaxy candidate
  66. GRB 200613A: Candidate afterglow from OAJ
  67. GRB 200613A: Swift ToO observations
  68. GRB 200612A: Swift detection of a burst
  69. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  70. GRB 200522A: Further HST F125W Observations
  71. IceCube-200530A: not observable by Fermi-GBM
  72. IceCube-200530A: Candidate Counterparts from the Zwicky Transient Facility
  73. IceCube-200530A: No ANTARES neutrino counterpart
  74. IceCube-200530A - IceCube observation of a high-energy neutrino candidate event
  75. GRB 200529A: Swift detection of a burst
  76. GRB 200528A: Swift detection of a burst
  77. GRB 200524A: Correction to the GCN 27800
  78. GRB 200524A: 3.6m DOT observations of the afterglow candidate ZTF20abbiixp
  79. GRB 200524A: GROWTH-India confirmation of optical afterglow
  80. GRB 200524A: Swift ToO observations
  81. IceCube-200523A: Upper limits from Fermi-GBM Observations
  82. IceCube-200523A - IceCube observation of a high-energy neutrino candidate event
  83. GRB 200522A: Coincident catalogued galaxy at z~0.4
  84. GRB 200517A: Swift-XRT Confirmation of afterglow
  85. GRB 200519A: R-band follow-up from HCT
  86. GRB 200519A: LCO Optical Afterglow Detection
  87. GRB 200519A: Swift detection of a burst with an optical afterglow
  88. GRB 200517A: Tiled Swift observations
  89. Swift Detection of a burst from SGR Swift J1818.0-1607
  90. GRB 200512A: Swift detection of a burst
  91. IceCube-200512A: No Candidate Counterparts from the Zwicky Transient Facility
  92. IceCube-200512A: IceCube observation of a high-energy neutrino candidate event
  93. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  94. FRB/X-ray bursts from SGR 1935+2154: No Neutrino Counterpart in ANTARES data
  95. Swift Detection of a burst from SGR Swift J1818.0-1607
  96. IceCube-200425A: Upper limits from Fermi-GBM Observations
  97. Gagarin-day GRB 200412B: observations with the 3.6m Devasthal Optical Telescope
  98. IceCube-200425A - IceCube observation of a high-energy neutrino candidate event
  99. GRB 200425A: Swift detection of a burst
  100. GRB 200424A: Swift ToO observations

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