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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"

3759 results found.

  1. GRB 190627A: NUTTelA-TAO optical counterpart observations
  2. GRB 190628A: Fermi GBM Final Real-time Localization
  3. Fermi trigger No 583111521 Global MASTER-Net observations report
  4. Swift Trigger 911102: a possible GRB
  5. Fermi trigger No 582856902 Global MASTER-Net observations report
  6. Fermi trigger No 582759998 Global MASTER-Net observations report
  7. Fermi trigger No 582615488 Global MASTER-Net observations report
  8. Fermi trigger No 582304592 Global MASTER-Net observations report
  9. GRB 190613B: SEDM Observations
  10. Fermi trigger No 582115625 Global MASTER-Net observations report
  11. IPN Triangulation of GRB 190611B
  12. Fermi trigger No 581889628 Global MASTER-Net observations report
  13. Fermi trigger No 581882394 Global MASTER-Net observations report
  14. LIGO/Virgo S190602aq: Upper limits from CALET observations
  15. LIGO/Virgo S190602aq: Coverage and upper limits from MAXI/GSC observations
  16. Fermi Fermi trigger No 581002688 Global MASTER-Net observations report
  17. GRB 190530A: Swift/UVOT Detection
  18. GRB 190530A: Swift-XRT afterglow detection
  19. GRB 190530A: GWAC-F30 optical detection
  20. GRB 190530A: OAJ optical detection
  21. GRB 190530A: AGILE/GRID analysis
  22. LIGO/Virgo S190519bj: AstroSat CZTI upper limits
  23. LIGO/Virgo S190521r: CNEOST follow-up observations
  24. Fermi GRB190525.67 Global MASTER-Net observations report
  25. LIGO/Virgo S190521r: No optical counterpart from SVOM/GWAC observations.
  26. LIGO/Virgo S190521g: No optical counterpart from SVOM/GWAC-F30 observations.
  27. LIGO/Virgo S190521g: No optical counterpart from SVOM/GWAC observations.
  28. LIGO/Virgo S190521g: No Counterparts in DDOTI/OAN Optical Observations
  29. S190519bj: No transient candidates from CALET observations
  30. LIGO/Virgo S190512at: SVOM/GWAC-F60A observations
  31. LIGO/Virgo S190519bj Global MASTER-Net observations report
  32. LIGO/Virgo S190517h: CALET Observations
  33. LIGO/Virgo S190518bb Global MASTER-Net observations report
  34. LIGO/Virgo S190517h Global MASTER-Net observations report
  35. LIGO/Virgo S190513bm: Swope follow-up observations
  36. LIGO/Virgo S190513bm : TAROT-Calern and TAROT-Chile (TCA/TCH)/GRANDMA observation report.
  37. LIGO/Virgo S190513bm: CALET Observations
  38. LIGO/Virgo S190513bm: Lick/KAIT Follow-Up Observations
  39. LIGO/Virgo S190510g: Swift-XRT observations and results
  40. LIGO/Virgo S190512at: CALET Observations
  41. LIGO/Virgo S190513bm: AGILE GRID observations
  42. LIGO/Virgo S190513bm: INTEGRAL prompt observation
  43. LIGO/Virgo S190513bm: AGILE MCAL observation
  44. LIGO/Virgo S190513bm Global MASTER-Net observations report
  45. LIGO/Virgo S190510g: Pan-STARRS and ATLAS observations and candidates
  46. LIGO/Virgo S190512at Global MASTER-Net observations report
  47. GRB 190512A: Fermi GBM observation
  48. LIGO/Virgo S190510g: CALET Observations
  49. LIGO/Virgo S190510g: MASTER OT detection inside low surface brightness galaxy
  50. GRB 190511A: Fermi GBM observation
  51. LIGO/Virgo S190510g: DESGW counterpart candidates over 80% of the GW localization area
  52. LIGO/Virgo S190510g: Dabancheng/HMT Follow-Up Observations
  53. LIGO/Virgo S190510g: SOAR/Goodman follow-up observations
  54. LIGO/Virgo S190510g: CNEOST Follow-Up Observations
  55. LIGO/Virgo S190510g: J-GEM optical/NIR follow-up observations
  56. LIGO/Virgo S190510g: Lick/KAIT Follow-Up Observations
  57. LIGO/Virgo S190510g: Lulin Optical Follow-up Observations
  58. LIGO/Virgo S190425z: CAHA-GRANDMA Observation of the Swift UVOT Source
  59. LIGO/Virgo S190426c: Archival VLASS Observations of ZTF19aassfws 14 days prior to Merger
  60. Fermi GRB190507.97 Global MASTER-Net observations report
  61. Fermi GRB190507.27 Global MASTER-Net observations report
  62. IceCube-190504A: MASTER optical monitoring analysis
  63. Fermi Trigger 578903308 / GRB 190507270 / GRB190507A: BALROG localization
  64. GRB 190507A: Fermi GBM Final Real-time Localization
  65. Fermi GRB190505.05 Global MASTER-Net observations report
  66. Fermi GRB190504.68 Global MASTER-Net observations report
  67. LIGO/Virgo S190503bf Global MASTER-Net observations report
  68. IceCube-190503A: Lick/KAIT Follow-Up Observations
  69. IPN triangulation of GRB 190504A (short)
  70. LIGO/Virgo S190503bf: Fermi-GBM Observations
  71. LIGO/Virgo S190503bf: INTEGRAL prompt observation
  72. LIGO/Virgo S190425z: Insight-HXMT observation and counterpart search
  73. Fermi GRB190501.79 Global MASTER-Net observations report
  74. LIGO/Virgo S190426c: PS1 historical detections and ZTF photometry of Gaia19boq AT2019egk
  75. LIGO/Virgo S190425z: 1.3-m optical imaging of UVOT transient field
  76. LIGO/Virgo S190426c: YAHPT Optical Observation
  77. LIGO/Virgo S190425z: KPED Follow-Up of ZTF transients
  78. LIGO/Virgo S190426c: GRAWITA transients from Asiago Schmidt wide field observations
  79. LIGO/Virgo S190425z: DECam Observations of the UVOT Candidate Region
  80. LIGO/Virgo S190426c: Continued LOAO Observation
  81. LIGO/Virgo S190425z: VISTA K-band observations of the Swift/UVOT Transient
  82. Fermi Trigger 578170097 / GRB 190428783 / GRB190428A: BALROG localization
  83. LIGO/Virgo S190426c: Additional Candidates from the Zwicky Transient Facility
  84. LIGO/Virgo S190426c: Continued infrared wide-field search with Palomar Gattini-IR
  85. LIGO/Virgo S190425z : IRSF/SIRIUS NIR photometric follow-up observation of the Swift/UVOT Transient
  86. LIGO/Virgo S190426c: OAJ-GRANDMA observation report
  87. LIGO/Virgo S190425z: No source found at UVOT source location at 6 hrs after LVC report
  88. LIGO/Virgo S190426c: DDOTI/OAN Optical Observations
  89. LIGO/Virgo S190425z: Lulin observations of the Swift/UVOT transient
  90. LIGO/Virgo S190426c: COATLI Optical Observations of Galaxies
  91. LIGO/Virgo S190426c: MMT Follow-Up Observations
  92. LIGO/Virgo S190426c: Lick/KAIT Follow-Up Observations
  93. GRB 190427A: COATLI Optical Observations
  94. LIGO/Virgo S190426c: CNEOST Optical Observations
  95. LIGO/Virgo S190425z: CNEOST Optical Observations
  96. LIGO/Virgo S190425z: BOOTES-5/JGT observations of galaxies
  97. LIGO/Virgo S190425z: Additional Pan-STARRS transients in the skymap
  98. LIGO/Virgo S190425z: GRANDMA follow-up observations with Les Makes-T60, AZT-8 and Abastumani-T70
  99. LIGO/Virgo S190426c: SAO optical observation
  100. LIGO/Virgo S190425z: Further MMT Follow-Up Observations

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