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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"

8481 results found.

  1. GRB 200729A: Swift detection of a burst
  2. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  3. GRB 200723A: Swift ToO observations
  4. GRB 200723A: GOTO candidate afterglow and host galaxy
  5. AMON IC_HAWC 170720: No Neutrino Counterpart detected with ANTARES
  6. GRB 200716C: Optical observations from HCT
  7. GRB 200522A: HST NIR counterpart confirmation
  8. GRB 200716C: Swift detection of a burst with an optical counterpart
  9. GRB 200715A: Swift ToO observations
  10. GRB 200714E: Swift ToO observations
  11. GRB 200522A: Candidate Optical/nIR Counterpart from Gemini and HST Imaging
  12. GRB 200713A: Swift detection of a burst
  13. GRB 200711A: KAIT Optical Upper Limit
  14. GRB 200711A: Swift detection of a burst
  15. GRB 200709B/HAWC-200907A: Swift-XRT further observations
  16. HAWC-200907A: No Neutrino Counterpart detected with ANTARES
  17. GRB 200709B: Tiled Swift observations
  18. Trigger 980513: Swift detection of SGR Swift J1818.0-1607
  19. Fermi-GBM Sub-Threshold Detection of GRB 200701A
  20. GRB 200630A: Swift detection of a burst
  21. GRB 200623A: Further MMTCam Observations of XRT Source #3
  22. GRB 200623A: LBT optical observations
  23. GRB 200625A: Swift ToO observations
  24. GRB 200623A: Swift/UVOT Upper Limits
  25. GRB 200623A: OAJ deep multi-color imaging, XRT #2 is pre-detected
  26. GRB 200623A: TNG optical observations
  27. GRB 200623A: AbAO afterglow candidate within XRT #2
  28. GRB 200623A: Swift ToO observations
  29. IceCube-200620A: No significant detection in HAWC
  30. IceCube-200620A: Upper limits from a search for additional neutrino events in IceCube
  31. IceCube-200620A: MASTER previous detection of ZTF20abgvabi/AT2020ncr
  32. IceCube-200620A: not observable by Fermi-GBM
  33. IceCube-200620A: One Candidate Counterpart from the Zwicky Transient Facility
  34. IceCube-200620A: No ANTARES neutrino counterpart
  35. IceCube-200620A - IceCube observation of a high-energy neutrino candidate track-like event
  36. LIGO/Virgo MS200618aq: Retraction of a test binary neutron star candidate
  37. LIGO/Virgo MS200619bf: Retraction of a test binary neutron star candidate
  38. LIGO/Virgo MS200618bx: Retraction of a test binary neutron star candidate
  39. LIGO/Virgo MS200618bq: Retraction of a test binary neutron star candidate
  40. IceCube-200530A - SN2020lls likely unrelated
  41. LIGO/Virgo MS200614ct: Identification of a test binary black hole candidate
  42. IceCube-200615A: No significant detection in HAWC
  43. IceCube-200614A: No significant detection in HAWC
  44. IceCube-200615A: Upper limits from a search for additional neutrino events in IceCube
  45. Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
  46. LIGO/Virgo MS200615ce: Identification of a test binary black hole candidate
  47. LIGO/Virgo MS200614bz: Test Identification of a binary neutron star candidate
  48. IceCube-200615A: Upper limits from Fermi-GBM Observations
  49. IceCube-200614A: Upper limits from a search for additional neutrino events in IceCube
  50. IceCube-200614A: not observable by Fermi-GBM
  51. LIGO/Virgo MS200615h: Retraction of a test binary neutron star candidate
  52. IceCube-200615A: IceCube observation of a high-energy neutrino candidate event
  53. IceCube-200614A - IceCube observation of a high-energy neutrino candidate track-like event
  54. GRB 200613A: Kitab and AbAO optical afterglow observations, host galaxy candidate
  55. GRB 200613A: Candidate afterglow from OAJ
  56. GRB 200613A: Swift ToO observations
  57. GRB 200612A: Swift detection of a burst
  58. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  59. GRB 200522A: Further HST F125W Observations
  60. Correction to the GCN 27886: Previous bursts of 1RXS J1708-4009 (Swift trigger 975998)
  61. 1RXS J1708−4009: Swift-BAT refined analysis
  62. Swift detection of an SGR-like burst from 1RXS J1708−4009
  63. IceCube-200530A: Upper limits from a search for additional neutrino events in IceCube
  64. IceCube-200530A: not observable by Fermi-GBM
  65. IceCube-200530A: No significant detection in HAWC
  66. IceCube-200530A: Candidate Counterparts from the Zwicky Transient Facility
  67. IceCube-200530A: No ANTARES neutrino counterpart
  68. IceCube-200530A - IceCube observation of a high-energy neutrino candidate event
  69. GRB 200529A: Swift detection of a burst
  70. GRB 200528A: Swift detection of a burst
  71. IceCube-200523A: Upper limits from a search for additional neutrino events in IceCube
  72. GRB 200522A: HST F125W new point source detection
  73. GRB 200522A: Hubble Space Telescope Near-IR F160W Observations
  74. GRB 200524A: Correction to the GCN 27800
  75. GRB 200524A: 3.6m DOT observations of the afterglow candidate ZTF20abbiixp
  76. GRB 200524A: GROWTH-India confirmation of optical afterglow
  77. GRB 200524A: Swift ToO observations
  78. IceCube-200523A: Upper limits from Fermi-GBM Observations
  79. IceCube-200523A - IceCube observation of a high-energy neutrino candidate event
  80. GRB 200522A: Coincident catalogued galaxy at z~0.4
  81. GRB 200517A: Swift-XRT Confirmation of afterglow
  82. GRB 200519A: R-band follow-up from HCT
  83. GRB 200519A: LCO Optical Afterglow Detection
  84. Fermi GBM Sub-Threshold Detection of GRB 200517A
  85. GRB 200519A: Swift detection of a burst with an optical afterglow
  86. GRB 200517A: Tiled Swift observations
  87. Swift Detection of a burst from SGR Swift J1818.0-1607
  88. GRB 200514B: GROWTH-India follow-up of ZTF20aazpphd (AT2020jww)
  89. IceCube-200512A: Upper limits from a search for additional neutrino events in IceCube
  90. Fermi GBM Sub-Threshold Detection of GRB 200512A
  91. GRB 200512A: Swift detection of a burst
  92. IceCube-200512A: No Candidate Counterparts from the Zwicky Transient Facility
  93. IceCube-200512A: IceCube observation of a high-energy neutrino candidate event
  94. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  95. FRB/X-ray bursts from SGR 1935+2154: No Neutrino Counterpart in ANTARES data
  96. Swift Detection of a burst from SGR Swift J1818.0-1607
  97. SGR 1935+2154 the Insight-HXMT observation plan
  98. Fermi GBM observation of a bright flare from magnetar SGR 1935+2154
  99. IceCube-200425A: No significant detection in HAWC
  100. IceCube-200425A: Upper limits from a search for additional neutrino events in IceCube

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