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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"
  1. GRB 050904: BAT refined analysis of partial data set
  2. GRB 050904: TAROT optical measurements
  3. GRB050904: Optical Observations
  4. GRB 050904: Environmental Constraints
  5. GRB 050904: Possible High-Redshift GRB
  6. GRB 050904: SOAR/PROMPT Observations
  7. GRB050904: P60 Observations
  8. GRB 050904: TAROT optical limits
  9. GRB050904: Swift-BAT detection of a probable burst
  10. Swift-BAT triggers 153461-153465 are not GRBs
  11. Retraction of Swift-BAT trigger #153355
  12. GRB 050824: MDM Observations
  13. GRB 050827: Swift XRT preliminary analysis results
  14. IBAS Alerts 2641 and 2642: not a real GRB
  15. Swift Trigger #152652 is not a GRB
  16. GRB 050827 : OSN 1.5m optical observations
  17. GRB 050827: P200 NIR Observations
  18. GRB050827: Swift/UVOT upper limits
  19. GRB 050827: Optical Limit
  20. GRB 050827: XRT possible afterglow detection
  21. GRB 050826 : Lulin R band observation
  22. GRB050824: Maidanak optical limits
  23. GRB050820A: RTT150 optical observations
  24. GRB050827: RTT150 optical observations
  25. GRB 050827: Swift-BAT refined analysis
  26. GRB050827: Swift-BAT detection of a burst
  27. Subaru Observations of GRB050724
  28. GRB 050826: Optical Candidate
  29. GRB050824, HETE-2 Observation
  30. GRB 050826: Swift XRT preliminary analysis results
  31. GRB 050826: BAT refined analysis
  32. GRB050826: Swift/UVOT early upper limits
  33. GRB050824: First 2 hours of power low optical decay?
  34. GRB 050826: Swift XRT position
  35. GRB050826: Swift-BAT detection of a long burst
  36. GRB050824: MASTER final analysis of the OT observations
  37. Possible GRB050825:MASTER optical observations
  38. Swift-BAT trigger 152038 is definitely not a GRB
  39. GRB050824: CORRECTION to UVOT observing times
  40. Swift-BAT trigger 152038 is probably not a GRB
  41. GRB050824: Swift/UVOT detection of fading afterglow
  42. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  43. GRB050824, I-band imaging
  44. GRB050824: Radio Observations
  45. GRB 050824: Spectroscopic redshift from the VLT
  46. GRB 050822: refined XRT analysis
  47. GRB 050824: XRT refined analysis and possible afterglow detection
  48. GRB 050824: BAT refined analysis of a soft weak burst
  49. GRB050824: MASTER:OT decay
  50. GRB050824: MASTER observation OT
  51. GRB050805a: MASTER optical candidat
  52. GRB 050824: ROTSE-III Optical Limits
  53. GRB050824: Swift-BAT detection of a burst
  54. GRB 050824 optical candidate
  55. GRB050820A: RTT150 optical observations
  56. GRB050820a: PROMPT RcIc Observations
  57. GRB050815: Maidanak optical observation
  58. XRF050509c: Radio upper limits from GMRT
  59. VLT/UVES spectroscopy of GRB050820
  60. GRB050822: Swift/UVOT upper limits
  61. GRB 050820A BAT observations of second, larger episode of emission
  62. GRB050813: Maidanak I-band observations
  63. GRB 050822: Swift-BAT refined analysis
  64. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  65. GRB050820B at FRAM
  66. GRB050820A: RTT150 optical observations
  67. GRB 050820a - corrections to GCN 3846
  68. Swift/UVOT UV Photometry of GRB 050820B
  69. GRB 050822: ROTSE-III Prompt Optical Limits
  70. GRB 050822: Swift detection of a long burst
  71. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  72. GRB050820A: Radio Observation
  73. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  74. GRB050820a BVRcIc field photometry
  75. GRB050820B XMM-Newton observation
  76. GRB 050820a: NIR Observations by WIRO
  77. GRB 050820B: Swift XRT position
  78. GRB050820B: Planned XMM-Newton observation
  79. GRB050820B: Refined analysis of the Swift-BAT burst
  80. GRB050820B: BAT-Swift detection of a bright GRB
  81. Swift/UVOT photometry of GRB050820
  82. GRB050820: refined XRT analysis
  83. GRB 050820: Early RAPTOR detections
  84. GRB 050820 Swift-BAT refined analysis
  85. GRB 050820: P60 Temporal Decay Index
  86. GRB 050820: High Resolution Spectroscopy from Keck
  87. GRB050819: refined XRT analysis
  88. GRB050819: RTT150 optical observations
  89. GRB 050820: Swift detection of a GRB
  90. GRB050820: Optical afterglow from P60
  91. GRB 050819 Swift-BAT refined analysis
  92. GRB050819: Swift XRT position
  93. GRB050819: Swift-BAT detection of a weak burst
  94. Swift-BAT trigger 150993 is not a GRB
  95. Swift Trigger 150823 is HETE J1900.1-2455
  96. GRB 050817: Optical observations
  97. GRB 050815: Radio Observation
  98. GRB050814: Radio Observation
  99. GRB050817: Negative Optical Observations
  100. GRB050817: Swift-BAT Detection of a burst

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