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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"

7448 results found.

  1. LIGO/Virgo MS200618bq: Retraction of a test binary neutron star candidate
  2. IceCube-200530A - SN2020lls likely unrelated
  3. LIGO/Virgo MS200614ct: Identification of a test binary black hole candidate
  4. Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
  5. LIGO/Virgo MS200615ce: Identification of a test binary black hole candidate
  6. LIGO/Virgo MS200614bz: Test Identification of a binary neutron star candidate
  7. IceCube-200615A: Upper limits from Fermi-GBM Observations
  8. IceCube-200614A: not observable by Fermi-GBM
  9. LIGO/Virgo MS200615h: Retraction of a test binary neutron star candidate
  10. IceCube-200615A: IceCube observation of a high-energy neutrino candidate event
  11. IceCube-200614A - IceCube observation of a high-energy neutrino candidate track-like event
  12. GRB 200613A: Kitab and AbAO optical afterglow observations, host galaxy candidate
  13. GRB 200613A: Candidate afterglow from OAJ
  14. GRB 200613A: Swift ToO observations
  15. GRB 200612A: Swift detection of a burst
  16. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  17. GRB 200522A: Further HST F125W Observations
  18. IceCube-200530A: not observable by Fermi-GBM
  19. IceCube-200530A: Candidate Counterparts from the Zwicky Transient Facility
  20. IceCube-200530A: No ANTARES neutrino counterpart
  21. IceCube-200530A - IceCube observation of a high-energy neutrino candidate event
  22. GRB 200529A: Swift detection of a burst
  23. GRB 200528A: Swift detection of a burst
  24. GRB 200524A: Correction to the GCN 27800
  25. GRB 200524A: 3.6m DOT observations of the afterglow candidate ZTF20abbiixp
  26. GRB 200524A: GROWTH-India confirmation of optical afterglow
  27. GRB 200524A: Swift ToO observations
  28. IceCube-200523A: Upper limits from Fermi-GBM Observations
  29. IceCube-200523A - IceCube observation of a high-energy neutrino candidate event
  30. GRB 200522A: Coincident catalogued galaxy at z~0.4
  31. GRB 200517A: Swift-XRT Confirmation of afterglow
  32. GRB 200519A: R-band follow-up from HCT
  33. GRB 200519A: LCO Optical Afterglow Detection
  34. GRB 200519A: Swift detection of a burst with an optical afterglow
  35. GRB 200517A: Tiled Swift observations
  36. Swift Detection of a burst from SGR Swift J1818.0-1607
  37. GRB 200512A: Swift detection of a burst
  38. IceCube-200512A: No Candidate Counterparts from the Zwicky Transient Facility
  39. IceCube-200512A: IceCube observation of a high-energy neutrino candidate event
  40. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  41. FRB/X-ray bursts from SGR 1935+2154: No Neutrino Counterpart in ANTARES data
  42. Swift Detection of a burst from SGR Swift J1818.0-1607
  43. IceCube-200425A: Upper limits from Fermi-GBM Observations
  44. Gagarin-day GRB 200412B: observations with the 3.6m Devasthal Optical Telescope
  45. IceCube-200425A - IceCube observation of a high-energy neutrino candidate event
  46. GRB 200425A: Swift detection of a burst
  47. GRB 200424A: Swift ToO observations
  48. IceCube-200421A: No Neutrino Counterpart in ANTARES data
  49. IceCube-200421A: not observable by Fermi-GBM
  50. IceCube-200421A - IceCube observation of a high-energy neutrino candidate event
  51. GRB 200412B: Swift XRT confirmation of afterglow and UVOT upper limits
  52. Konus-Wind observation of GRB 200415A (a magnetar Giant Flare in Sculptor Galaxy?)
  53. GRB 200416A: Swift detection of a burst with an optical afterglow
  54. GRB 200412B: Fermi GBM detection
  55. GRB 200412B: Tiled Swift observations
  56. IceCube-200410A: Upper limits from Fermi-GBM Observations
  57. IceCube-200410A - IceCube observation of a high-energy neutrino candidate event
  58. GRB 200409A: No detection of radio emission 5 hours post-burst
  59. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  60. GRB 200405B: ATCA follow-up and ASKAP limits on pre-burst radio emission
  61. GRB 200409A: Swift detection of a burst with an optical counterpart
  62. GRB 200405B: Swift ToO observations
  63. GRB 200325B: Swift-XRT and UVOT observations
  64. GRB 200325B: Mondy, CrAO, AbAO afterglow confirmation and refined photometry of MASTER OT J111012.51+274912.8
  65. GRB 200325B: Swift ToO observations
  66. GRB 200324A: Swift detection of a burst
  67. LIGO/Virgo S200316bj: no counterpart candidate in SVOM/GWAC-F30 observations
  68. LIGO/Virgo S200316bj: Updated Sky Localization and EM Bright Classification
  69. Chandra observations of GW170817 at 2.5 years since merger (All epochs 4 of 4)
  70. GW170817: Continued X-ray emission detected with Chandra at 940 days post-merger
  71. LIGO/Virgo S200316bj: no counterpart candidate in SVOM/GWAC observations
  72. LIGO/Virgo S200316bj: No neutrino candidates at Pierre Auger Observatory
  73. LIGO/Virgo S200316bj: upper limits from AGILE/GRID observations
  74. LIGO/Virgo S200316bj: Upper limits from Fermi-GBM Observations
  75. LIGO/Virgo S200316bj : no neutrino counterpart candidate in ANTARES search
  76. LIGO/Virgo S200316bj: Upper limits from IceCube neutrino searches
  77. LIGO/Virgo S200316bj: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo S200311bg: Updated Sky Localization and EM Bright Classification
  79. Swift-BAT trigger 960986: Swift detection of a new SGR Swift J1818.0-1607
  80. LIGO/Virgo S200311bg: Not observable by CALET
  81. LIGO/Virgo S200224ca: DESGW Summary of DECam Observations
  82. LIGO/Virgo S200311bg: Upper limits from IceCube neutrino searches
  83. LIGO/Virgo S200311bg: Identification of a GW compact binary merger candidate
  84. Chandra observations of GW170817 ~ 2.5 years since merger (epoch 1 of 4)
  85. LIGO/Virgo S200308e: Retraction of GW compact binary merger candidate
  86. LIGO/Virgo S200302c: No notable candidates in GOTO imaging
  87. GRB 200306C: Swift detection of a burst with an optical counterpart
  88. LIGO/Virgo S200225q: No notable candidates in GOTO imaging
  89. LIGO/Virgo S200302c: AstroSat CZTI upper limits
  90. GRB 200303A: NOT optical observations
  91. LIGO/Virgo S200303ba: Retraction of GW compact binary merger candidate
  92. GRB 200303A: GOTO observations upper limit
  93. GRB 200303A: Swift detection of a burst
  94. LIGO/Virgo S200302c: Updated Sky Localization
  95. LIGO/Virgo S200302c: No counterpart candidates in HAWC observations
  96. LIGO/Virgo S200302c: Upper limits from Fermi-GBM Observations
  97. LIGO/Virgo S200302c : no neutrino counterpart candidate in ANTARES search
  98. LIGO/Virgo S200225q: AstroSat CZTI upper limits
  99. LIGO/Virgo S200219ac: AstroSat CZTI upper limits
  100. LIGO/Virgo S200302c: Upper limits from IceCube neutrino searches

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