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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"

3933 results found.

  1. LIGO/Virgo S190421ar: INTEGRAL prompt observation
  2. LIGO/Virgo S190421ar: Fermi-GBM Observations
  3. LIGO/Virgo S190421ar Global MASTER-Net observations report
  4. LIGO/Virgo S190421ar: HAWC follow-up
  5. AT LIGO-Virgo S190421ar: AGILE GRID observations
  6. LIGO/VIRGO S190421ar: IceCube Neutrino Search
  7. LIGO/Virgo S190421ar: Identification of a GW compact binary merger candidate
  8. LIGO-Virgo S190421ar: AGILE MCAL observations
  9. LIGO/Virgo S190408an: INTEGRAL follow-up observations
  10. LIGO/Virgo S190412m: SVOM/GWAC observations of the initial skymap
  11. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidates
  12. LIGO/Virgo S190412m: TAROT-GRANDMA observation report.
  13. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
  14. LIGO/Virgo S190412m: Palomar Gattini-IR Wide-field Infrared Follow-up
  15. LIGO/Virgo S190412m: GOTO optical coverage - no notable counterparts
  16. LIGO/Virgo S190412m: Fermi-LAT search for a high-energy gamma-ray counterpart
  17. LIGO/Virgo S190412m: Swift/BAT data search
  18. LIGO/Virgo S190412m: J-GEM optical/NIR follow-up observations
  19. LIGO/Virgo S190412m: Fermi-GBM Observations
  20. LIGO/Virgo S190412m: MAXI/GSC Observations
  21. LIGO-Virgo S190412m: AGILE GRID observations
  22. LIGO/Virgo S190405ar: Retraction of a GW binary merger candidate
  23. LIGO/Virgo S190412m: Insight-HXMT/HE observation
  24. LIGO/Virgo S190408an: ATLAS observations of the S190412m skymap
  25. LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
  26. LIGO/Virgo S190412m/G329483: ANTARES neutrino search
  27. LIGO/Virgo S190412m: Hobby-Eberly Telescope VIRUS observations of target galaxies.
  28. LIGO-Virgo S190412m: Search for neutrino counterparts with IceCube
  29. LIGO/Virgo S190412m: HAWC follow-up
  30. LIGO-Virgo S190412m: AGILE preliminary analysis
  31. LIGO/Virgo S190412m: MASTER early alert observation
  32. LIGO/Virgo S190412m: Identification of a GW binary merger candidate
  33. LIGO/Virgo S190408an: GROND Observations of MASTER OT J154209.55-431742.2
  34. LIGO/Virgo S190408an: Pan-STARRS observations and transients in the skymap
  35. LIGO/Virgo S190408an: MASTER OT J231043.63+470956.4 BOOTES-4 and 10.4m GTC follow-up observations
  36. LIGO/Virgo S190408an: MAXI/GSC Observations
  37. LIGO/Virgo S190408an: GRAWITA optical observations of MASTER OT J231043.63+470956.4
  38. LIGO/Virgo S190408an: CALET Observations
  39. LIGO/Virgo S190408an: TMTS Optical Observation
  40. LIGO/Virgo S190408an: DDOTI/OAN Optical Observations
  41. LIGO/Virgo S190408an: HMT optical observations
  42. LIGO/Virgo S190408an: MASTER 3 OT's more detection
  43. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  44. LIGO-Virgo S190408an: further AGILE GRID observations after T0
  45. LIGO/Virgo S190408an: SAGUARO follow-up observations
  46. LIGO/Virgo S190408an: MASTER OT is 27 day old ATLAS SN candidate and unrelated
  47. LIGO/Virgo S190408an: Insight-HXMT/HE observation
  48. LIGO/Virgo S190408an: MASTER OT detection
  49. LIGO/Virgo S190408an: Swift/BAT data search
  50. LIGO/Virgo S190408an: KMTNet observation
  51. LIGO-Virgo S190408an: AGILE GRID observations
  52. LIGO/Virgo S190408an: MASTER Global Robotic Net optical observations
  53. LIGO/Virgo S190408an: Identification of a GW binary merger candidate
  54. LIGO-Virgo S190408an: HAWC follow-up
  55. LIGO/Virgo S190408an: Fermi GBM Observation
  56. LIGO-Virgo GW S190408an: J-GEM optical/NIR follow-up observations
  57. LIGO-Virgo S190408an: AGILE MCAL observations
  58. LIGO/Virgo: Announcing the start of Observing Run 3 (O3) and the beginning of the public gravitational-wave alert era
  59. IPN Triangulation of GRB 190329A (long/bright)
  60. GRB 190114C: photometric detection of a SN component
  61. Improved Fermi/GBM GRB localizations
  62. IPN Triangulation of GRB 190304A (long)
  63. IPN Triangulation of GRB 190206A (short/extremely bright)
  64. GRB 190204A: Swift-BAT refined analysis
  65. IPN Triangulation of GRB 190129B (long/extremely bright)
  66. IPN Triangulation of GRB 190118A (long)
  67. CALET Gamma-Ray Burst Monitor: Policy change in the GCN circulars
  68. INTEGRAL observations of the events in the GWTC-1 catalog
  69. Fermi-GBM Observations During Four New GW-Detected BBH Mergers (Correction)
  70. Fermi-GBM Observations During Four New GW-Detected BBH Mergers
  71. IPN Triangulation of GRB 181121A (short)
  72. GRB 180728B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 554505003)
  73. GRB180913A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 558557292)
  74. IPN Triangulation of GRB 181008B (long)
  75. IPN Triangulation of GRB 180824A (short)
  76. LIGO/Virgo GW170817: A steep decline in the radio light curve and prediction for the X-rays
  77. IPN Triangulation of GRB 180728B (short)
  78. GRB 180720B: OSN detection, fading slower?
  79. GRB 180626C: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 551697835)
  80. IPN Triangulation of GRB 180626C (short)
  81. IPN Triangulation of GRB 180611A (long)
  82. IPN Triangulation of GRB 180605A (long)
  83. LIGO/Virgo G299232: LOFAR follow-up
  84. Fermi GBM triggers 544628550/180405571, 544542853/180404579, 544531428/180404447 are not GRBs
  85. IPN Triangulation of GRB 180326A (long)
  86. IPN Triangulation of GRB 180318A (long)
  87. IPN Triangulation of GRB 180317A (short/hard)
  88. IPN Triangulation of GRB 180223A (long)
  89. IPN Triangulation of GRB 180218A (long/bright)
  90. Fermi-GBM Detection of possible burst from AXP CXOU J164710.2-455216/PSR J1647-4552
  91. GRB 180205A: confirmation of Swift-BAT trigger time.
  92. LIGO/Virgo GW170817: Chandra X-ray Emission Continues to Rise ~156 Days Post-Merger
  93. LIGO/Virgo G298048 GRAWITA: VST-ESO PARANAL follow up of AT2017gfo
  94. IPN Triangulation of GRB 171216B
  95. LIGO/Virgo GW170817: X-ray observations confirm prediction made from radio data
  96. LIGO/Virgo GW170817: Further Hubble Space Telescope observations
  97. LIGO/Virgo G298048: Brightening X-ray Emission from GW170817/GRB170817A/SSS17a
  98. LIGO/Virgo GW170817: Chandra X-ray brightening of the counterpart 108 days since merger
  99. LIGO/Virgo G298048: Late-time detection of the X-ray afterglow with Chandra
  100. LIGO/Virgo G299232: LOFAR follow-up

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