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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"

22112 results found.

  1. GRB 050215b: Swift XRT Source Variability
  2. GRB 050215b : Lulin follow-up observation
  3. GRB 050215b, BOOTES-2 simultaneous optical observations
  4. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  5. GRB 050215b, BOOTES-1B optical limit
  6. GRB050215B: ROTSE-III optical observations
  7. GRB050215A: ROTSE-III Optical Observations
  8. GRB050209: TAROT optical observations
  9. GRB 050209(=U11568): Duration and spectrum
  10. short/hard GRB 050202, optical observations
  11. GRB050209: REM optical observations
  12. GRB 050209 I-band observation
  13. GRB 050209 Optical observations
  14. GRB050209: P60 Optical Observations
  15. GRB 050128: Radio observations
  16. GRB 050129: Optical observations
  17. GRB 050202: Short burst detected by Swift-BAT
  18. GRB 050128 Optical observation with REM
  19. GRB 050128: near-infrared observations with REM
  20. GRB050128,optical observations
  21. GRB050128 Swift-BAT observations
  22. GRB 050128: Swift XRT prompt afterglow position
  23. GRB050126: MASTER optical limit for KECK OT
  24. GRB050126: Burst Parameters Measured by BAT
  25. GRB050126: MASTER optical observations
  26. GRB050124: No Swift UVOT Detection of Afterglow Emission
  27. GRB 050124 I-band observation
  28. GRB050124,optical observation
  29. GRB050124: Updated Swift XRT Position and Fluxes
  30. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  31. GRB050124: Refined BAT position, spectral and fluence information
  32. GRB050124: Swift-BAT position of a double-peaked burst
  33. GRB 050123 : I-band follow-up observation
  34. GRB050123: optical limit 1.8h before GRB
  35. GRB050123,optical observation
  36. GRB 050123: KAIT observations
  37. CFHTLS optical transient unlikely to be a GRB
  38. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  39. GRB050117b: Swift-BAT detection of a weak burst
  40. GRB050117: MASTER optical observations
  41. MASTER:GRB050117 SWIFT
  42. GRB050117: Swift-BAT detection of a long multi-peaked burst
  43. GRB050117: Swift XRT Position
  44. Triangulation of Short Hard GRB050112 (large error box)
  45. SGR1806-20: Swift-BAT observations of two additional bursts
  46. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  47. Further VLA observations of SGR 1806-20
  48. SGR 1806-20 and extragalactic short-duration GRBs
  49. Further ATCA observations of SGR 1806-20
  50. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  51. SGR 1806-20, RHESSI observations of the 041227 giant flare
  52. Second-epoch VLA observations of SGR 1806-20
  53. SGR1806 VLA Observations
  54. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  55. GRB 041217: Optical observations
  56. GRB041228: ROTSE-III Optical Observations
  57. GRB041228: Swift-BAT detection of a burst
  58. GRB041219; RXTE ASM Observations
  59. GRB041226: ROTSE-III Optical Observations
  60. GRB041226: Swift-BAT detection of a burst
  61. GRB041223: decay of the afterglow
  62. GRB041224: ROTSE-III Optical Observations
  63. GRB 041224: near-infrared observations with REM
  64. GRB041224: Swift-BAT detection of a soft burst
  65. GRB041223: optical and NIR observations with REM
  66. GRB 041219: TAROT optical observations
  67. GRB 041218: TAROT optical observations
  68. GRB 041223: J-band observations of the afterglow
  69. GRB 041219c: PROMPT Observations
  70. GRB041223: ROTSE-III Optical Observations
  71. GRB041223: Swift-BAT detection of a bright long burst
  72. GRB 041218: optical observations
  73. GRB 041219 : optical follow-up observations
  74. GRB 041218 Optical Observations
  75. GRB041219: Continued NIR Observations
  76. GRB 041219 ,optical observation
  77. GRB 041219: Radio Afterglow Detection
  78. GRB 041218 : Radio Observations
  79. GRB 041218: R-band optical observations
  80. GRB041218: optical observations
  81. GRB041219: Confirmed NIR Afterglow
  82. Swift-BAT detection of the bright long burst GRB041219
  83. GRB 041219: Infrared Afterglow Candidate
  84. GRB041219, BVRcIc field calibration
  85. GRB 041219: Infrared Afterglow Candidate
  86. GRB041218, BVRcIc field calibration
  87. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  88. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  89. GRB 041217: PROMPT Observations
  90. GRB041217: optical limit 30 min after GRB
  91. GRB 041217: LCO40 Optical Observations and Possible Candidates
  92. GRB 041218 - A long GRB detected by integral
  93. GRB041217: NIR and optical observations with REM
  94. GRB041217: P60 Optical Observations
  95. GRB041217: Infrared Observations
  96. GRB041217: The First GRB Located On-Board Swift
  97. GRB041211: Faulkes Telescope continued optical monitoring
  98. Optical transient (GRB?) in Lynx
  99. GRB041211: RAPTOR observations
  100. GRB041211: Ashra Prototype optical observation

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