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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"

20951 results found.

  1. Fermi GBM Observations of SGR 1935+2154
  2. GRB 150222A: GROND optical afterglow candidate
  3. GRB 150222A: TNG optical observations
  4. Fermi GBM trigger 150223068 is not a GRB
  5. GRB 150222A: Mondy optical observations
  6. GRB 150222A: Zadko observatory - Gingin optical observations
  7. GRB 150222A: MASTER early optical observations
  8. GRB 150219A: Swift-XRT afterglow detection
  9. Trigger 631747: Swift detection of 4U 0614+09
  10. GRB 150219A: Swift ToO observations
  11. GRB 150213B: P60 Observations
  12. GRB 150213B: Swift/UVOT Detection
  13. GRB 150213B: RATIR Optical and NIR Observations
  14. GRB 150213B: AAO optical observations
  15. GRB 150213B: optical detection from the NOT
  16. GRB 150212A: Swift/UVOT Observations
  17. GRB 150213B: Tautenburg Afterglow Detection
  18. GRB 150212A: RATIR Optical and NIR Observations
  19. GRB 150212A: Skynet DSO14/GORT observations
  20. GRB 150212A: MASTER optical observations
  21. GRB 150210A: Swift-XRT observations
  22. GRB150212A: P60 Afterglow Candidate
  23. GRB 150211A: Swift/UVOT Upper Limits
  24. GRB 150211A: KAIT Optical Upper Limit
  25. GRB 150210A: Tiled Swift observations
  26. GRB 150211A: RATIR Optical and NIR Observations
  27. GRB 150211A: Swift-XRT observations
  28. GRB 150211A: MASTER early optical observations
  29. GRB 150101B/ Swift J123205.1-105602: Second epoch Chandra observations
  30. GRB 150204A: GROND observations
  31. GRB 150202B: Swift/XRT afterglow confirmation
  32. GRB 150204A: Swift/XRT afterglow confirmation
  33. GRB 150206A: Swift/UVOT Detection
  34. GRB 140206B: Continued iPTF Observations
  35. GRB 150206A: GROND afterglow observations
  36. GRB 150206B: Fermi GBM detection
  37. Trigger 630047: Swift detection of 1RXS J180408.9-342058
  38. GRB 150206B: iPTF Optical Observations
  39. GRB 150204A: LCOGT-Sutherland and Siding Springs observations
  40. GRB 150204A: Swift/UVOT Upper Limits
  41. GRB 150204A: Swift-XRT observations
  42. GRB 150204A: Swift ToO observations
  43. GRB 150202B: Swift XRT/UVOT observations
  44. GRB 150203A: RAPTOR Limits Beginning at the Gamma-Ray Emitting Interval
  45. GRB 150203A: Swift/UVOT Upper Limits
  46. GRB 150202B: Tiled Swift observations
  47. GRB 150202A: Swift/UVOT Upper Limits
  48. GRB 150203A: REM optical and NIR observations
  49. GRB 150203A: TAROT La Silla observatory optical observations
  50. GRB 150203A: GROND Upper limits
  51. GRB 150203A: RATIR Optical and NIR Observations
  52. GRB 150202A: GROND Upper limits
  53. GRB 150203A: P60 observations
  54. GRB 150203A: KAIT Optical Upper Limit
  55. GRB 150201A: Swift/UVOT Upper Limits
  56. GRB 150201A: GROND upper limits
  57. GRB 150120B: Khureltogot optical observations
  58. GRB 150128A: MASTER OT detction during inspection
  59. GRB 150120A: 9.8 GHz VLA upper limit
  60. GRB 150120A: Gemini-N imaging and host redshift
  61. GRB 150120A: possible AMI 15 GHz detection
  62. GRB 150123A: Swift/UVOT observations
  63. GRB 150123A: Swift-XRT observations
  64. GRB 150120B: Mondy optical observations
  65. GRB 150123A Tiled Swift observations
  66. GRB 150120B: RATIR Optical and NIR Observations
  67. GRB 150120B: FTN early optical light curve
  68. GRB 150120B: Swift/UVOT Upper Limits
  69. GRB 150120B, Optical observations
  70. GRB 150120B: GROND Afterglow Detection
  71. GRB 150120B: Additional P60 observations
  72. GRB 150101B: Confirmation of a fading optical counterpart
  73. GRB 150120A: KAIT Optical Upper Limit
  74. GRB 150101B/Swift J123205.1-105602: TNG NIR follow-up
  75. GRB 150120A: Swift/UVOT Upper Limits
  76. GRB 150110B: AMI 15 GHz detection of possible radio counterpart
  77. GRB 150101B/Swift J123205.1-105602, deep VLT observations
  78. GRB 150120A: Gemini-North optical imaging
  79. GRB 150120A: P60 optical observations
  80. GRB 150101B/Swift J123205.1-105602: continued WSRT radio and VLT optical observations
  81. The Swift Detection of a Large Flare from the RS CVn Binary SZ Psc
  82. GRB 150110C: Swift/UVOT Upper Limits
  83. GRB 150110C: Swift-XRT observations
  84. GRB 150110C Tiled Swift observations
  85. GRB 150110B: Swift/UVOT Upper Limits
  86. GRB 150101B/Swift J123205.1-105602: Chandra observations
  87. GRB 150101B / Swift J123205.1-105602: 9.8 GHz VLA observations
  88. GRB 150101B/Swift J123205.1-105602: WSRT radio observation
  89. GRB 150101B / Swift J123205.1-105602: X-ray counterpart is likely an AGN
  90. Radio upper limit on the GRB 141121A with the GMRT
  91. GRB 150101B/Swift J123205.1-105602: VLT observations and redshift
  92. Swift detection of 4U 1700+24 (= V* V934 Her)
  93. GRB 150103A: MASTER optical observations
  94. GRB 150101B: potential host galaxy redshift by GTC
  95. GRB 150103A: Swift/UVOT Upper Limits
  96. GRB 150103A: Zadko observatory - Gingin optical observations
  97. Swift J123205.1-105602: Magellan candidate afterglow
  98. Swift J123205.1-105602: XRT and UVOT observations of soft short burst source
  99. GRB 150101A: Swift/UVOT Upper Limits
  100. Swift-XRT and UVOT follow-up of iPTF14jko (GRB 141230A)

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