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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"

4256 results found.

  1. LIGO/Virgo S190425z: No source found at UVOT source location at 6 hrs after LVC report
  2. LIGO/Virgo S190425z: SVOM/GWAC-F60A observations
  3. LIGO/Virgo S190426c: DDOTI/OAN Optical Observations
  4. LIGO/Virgo S190426c: RATIR Optical and NIR Observations of Galaxies
  5. LIGO/Virgo S190426c: COATLI Optical Observations of Galaxies
  6. LIGO/Virgo S190425z: Transient found in Swift/UVOT counterpart search
  7. LIGO/Virgo S190425z: Further confirmation for the classification of PS19qp/AT 2019ebq as a supernova
  8. Fermi GRB190427.19 Global MASTER-Net observations report
  9. LIGO/Virgo S190426c: MMT Follow-Up Observations
  10. LIGO/Virgo S190426c: Lick/KAIT Follow-Up Observations
  11. LIGO/Virgo S190426c: CNEOST Optical Observations
  12. LIGO/Virgo S190425z: CNEOST Optical Observations
  13. LIGO/Virgo S190425z: BOOTES-5/JGT observations of galaxies
  14. LIGO/Virgo S190425z: Additional Pan-STARRS transients in the skymap
  15. LIGO/Virgo S190425z: GRANDMA follow-up observations with Les Makes-T60, AZT-8 and Abastumani-T70
  16. LIGO/Virgo S190426c: SAO optical observation
  17. LIGO/Virgo S190425z: Further MMT Follow-Up Observations
  18. LIGO/Virgo S190426c: INTEGRAL prompt observation
  19. Baksan Neutrino Observatory Alert 190405.62: Global MASTER-Net:LIGO/Virgo S190425z: PanSTARR OT AT2019ebq/PS19qp
  20. LIGO/Virgo S190425z: COATLI Observations of Galaxies
  21. LIGO/Virgo S190425z: TAROT-GRANDMA observation report
  22. LIGO/Virgo S190425z: KMTNet Observation
  23. LIGO/Virgo S190425z: Pan-STARRS observations and transients in the skymap
  24. LIGO/Virgo S190425z: ZTF19aarykkb Imaging from Las Cumbres Observatory
  25. LIGO/Virgo S190425z - GROWTH-India follow-up of two ZTF candidates
  26. LIGO/Virgo S190425z: ATLAS observations of the S190425z skymap
  27. LIGO/Virgo S190425z: J-GEM optical follow-up observations with Subaru/FOCAS
  28. LIGO/Virgo S190425z: Xinglong/Schmidt follow-up observations
  29. LIGO/Virgo S190425z: Lick/KAIT Follow-Up Observations
  30. LIGO/Virgo S190425z: further analysis of INTEGRAL data
  31. Fermi GRB190425.09 Global MASTER-Net observations report
  32. LIGO/Virgo S190421ar: Lick/KAIT Follow-Up Observations
  33. GRB 190422A: Swift detection of a burst
  34. LIGO/Virgo S190421ar: Fermi-GBM Observations
  35. LIGO/Virgo S190421ar Global MASTER-Net observations report
  36. Fermi GRB190419.41 Global MASTER-Net observations report
  37. Fermi trigger 576241792 / GRB 190406B: MASTER optical observation
  38. GRB 190326A: Swift XRT and UVOT follow-up observations
  39. LIGO/Virgo S190412m: TAROT-GRANDMA observation report.
  40. CORRECTED TARGET NAME: GRB 190408A: MAXI/GSC detection
  41. GRB 140408A: MAXI/GSC detection
  42. GRB 140404B: MAXI/GSC detection
  43. GRB 190330A: MITSuME Akeno and Okayama optical upper limits
  44. Trigger 896552: Swift detection of PSR B1055-52
  45. GRB 190331B: Swift observations of a ground-detected burst
  46. GRB 190329A: CALET Gamma-Ray Burst Monitor detection
  47. GRB 190326A: Swift-BAT refined analysis - a soft-short GRB or an SGR
  48. GRB 190320A: Swift-BAT refined analysis
  49. GRB 190311A: Swift-BAT refined analysis
  50. GRB190219A: MASTER Global Robotic Net optical observation
  51. GRB 180703A: VLT/MUSE host galaxy redshift measurement
  52. Konus-Wind observation of GRB 190206A
  53. IPN Triangulation of GRB 190206A (short/extremely bright)
  54. Konus-Wind observation of GRB 190203A
  55. GRB 190202A: R and I band observation from HCT
  56. GRB 190129B: MASTER Global Robotic Net optical observation
  57. GRB 190129A: CALET Gamma-Ray Burst Monitor detection
  58. GRB 190129A: Fermi GBM detection
  59. GRB 190129A: MAXI/GSC detection
  60. Swift Trigger 886157: MASTER optical observation
  61. Swift Trigger 886157: Swift detection of a new transient Swift J1728.9-3613
  62. GRB 190123A: Swift detection of a burst
  63. IPN Triangulation of GRB 190118A (long)
  64. GRB 190114C: OASDG optical observations
  65. GRB 190114C: NOT optical counterpart and redshift
  66. GRB 190114C: Swift detection of a very bright burst with a bright optical counterpart
  67. IceCube-190104A: AstroSat CZTI counterpart search
  68. FRB 181228: Global MASTER Net optical inspection
  69. GRB 181222B: Global MASTER Net observations of short bright Fermi GRB
  70. GRB 181222B: Global MASTER Net observations of the short bright Fermi GRB error box.
  71. Swift Trigger 878504 is not astrophysical
  72. GRB 181222A: MAXI/GSC detection
  73. GRB 181213A: Swift/UVOT Observations
  74. GRB 181213A: Mondy optical observations
  75. GRB 181213A: continued TSHAO optical observations
  76. GRB 181213A: Enhanced Swift-XRT position
  77. IPN Triangulation of GRB 181212A (long)
  78. GRB181213A: Swift/UVOT Detection
  79. GRB 181213A: Swift-XRT observations
  80. GRB 181213A: BOOTES-5/JGT optical observations
  81. GRB 181126A: Prompt enhanced Swift-XRT position
  82. IPN Triangulation of GRB 181121A (short)
  83. Fermi GRB 181105.31: Global MASTER Net optical observations
  84. GRB 181103A: MITSuME Okayama optical upper limits
  85. GRB 181030A: MASTER Net OT detection
  86. GRB 181030A: Swift detection of a burst with a possible optical counterpart
  87. IPN Triangulation of GRB 181028A (long)
  88. GRB 180728B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 554505003)
  89. GRB 181022A: Swift-XRT refined Analysis
  90. GRB 181022A: MITSuME Akeno optical upper limits
  91. GRB 181013A: Swift detection of a probable burst
  92. GRB 181010A: MASTER-Argentina OT detection
  93. GRB 180923A: MASTER inspection MAXI/GSC error box
  94. GRB 180923A: MAXI/GSC detection
  95. Konus-Wind of the very bright GRB 180914B
  96. GRB 180914A: MASTER automatic inspection
  97. GRB 180905A, Swift-BAT refined analysis
  98. GRB 180905A: MITSuME Akeno optical upper limits
  99. GRB 180828A: Swift detection of a GRB or possible Galactic Transient Swift J1754.9-2548
  100. GRB 180824A: MASTER inspection IPN short GRB error box

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