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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 050906: Bright galaxy in BAT error box
  2. GRB 050906: Swift/BAT Detection of a possible burst
  3. GRB 050904: More SOAR
  4. GRB 050904: photometric redshift
  5. GRB 050904: Swift/UVOT observations
  6. GRB 050904: Afterglow Astrometry
  7. GRB 050904: NIR object inside the XRT error box
  8. GRB 050904: early Swift XRT analysis results
  9. GRB 050904: SOAR YJ and PROMPT Ic Observations
  10. GRB 050904: BAT refined analysis of partial data set
  11. GRB 050904: TAROT optical measurements
  12. GRB050904: Optical Observations
  13. GRB 050904: Environmental Constraints
  14. GRB 050904: Possible High-Redshift GRB
  15. GRB 050904: SOAR/PROMPT Observations
  16. GRB050904: P60 Observations
  17. GRB 050904: TAROT optical limits
  18. GRB050904: Swift-BAT detection of a probable burst
  19. Swift-BAT triggers 153461-153465 are not GRBs
  20. Retraction of Swift-BAT trigger #153355
  21. GRB 050824: MDM Observations
  22. GRB 050827: Swift XRT preliminary analysis results
  23. IBAS Alerts 2641 and 2642: not a real GRB
  24. Swift Trigger #152652 is not a GRB
  25. GRB 050827 : OSN 1.5m optical observations
  26. GRB 050827: P200 NIR Observations
  27. GRB050827: Swift/UVOT upper limits
  28. GRB 050827: Optical Limit
  29. GRB 050827: XRT possible afterglow detection
  30. GRB 050826 : Lulin R band observation
  31. GRB050824: Maidanak optical limits
  32. GRB050820A: RTT150 optical observations
  33. GRB050827: RTT150 optical observations
  34. GRB 050827: Swift-BAT refined analysis
  35. GRB050827: Swift-BAT detection of a burst
  36. Subaru Observations of GRB050724
  37. GRB 050826: Optical Candidate
  38. GRB050824, HETE-2 Observation
  39. GRB 050826: Swift XRT preliminary analysis results
  40. GRB 050826: BAT refined analysis
  41. GRB050826: Swift/UVOT early upper limits
  42. GRB050824: First 2 hours of power low optical decay?
  43. GRB 050826: Swift XRT position
  44. GRB050826: Swift-BAT detection of a long burst
  45. GRB050824: MASTER final analysis of the OT observations
  46. Possible GRB050825:MASTER optical observations
  47. Swift-BAT trigger 152038 is definitely not a GRB
  48. GRB050824: CORRECTION to UVOT observing times
  49. Swift-BAT trigger 152038 is probably not a GRB
  50. GRB050824: Swift/UVOT detection of fading afterglow
  51. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  52. GRB050824, I-band imaging
  53. GRB050824: Radio Observations
  54. GRB 050824: Spectroscopic redshift from the VLT
  55. GRB 050822: refined XRT analysis
  56. GRB 050824: XRT refined analysis and possible afterglow detection
  57. GRB 050824: BAT refined analysis of a soft weak burst
  58. GRB050824: MASTER:OT decay
  59. GRB050824: MASTER observation OT
  60. GRB050805a: MASTER optical candidat
  61. GRB 050824: ROTSE-III Optical Limits
  62. GRB050824: Swift-BAT detection of a burst
  63. GRB 050824 optical candidate
  64. GRB050820A: RTT150 optical observations
  65. GRB050820a: PROMPT RcIc Observations
  66. GRB050815: Maidanak optical observation
  67. XRF050509c: Radio upper limits from GMRT
  68. VLT/UVES spectroscopy of GRB050820
  69. GRB050822: Swift/UVOT upper limits
  70. GRB 050820A BAT observations of second, larger episode of emission
  71. GRB050813: Maidanak I-band observations
  72. GRB 050822: Swift-BAT refined analysis
  73. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  74. GRB050820B at FRAM
  75. GRB050820A: RTT150 optical observations
  76. GRB 050820a - corrections to GCN 3846
  77. Swift/UVOT UV Photometry of GRB 050820B
  78. GRB 050822: ROTSE-III Prompt Optical Limits
  79. GRB 050822: Swift detection of a long burst
  80. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  81. GRB050820A: Radio Observation
  82. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  83. GRB050820a BVRcIc field photometry
  84. GRB050820B XMM-Newton observation
  85. GRB 050820a: NIR Observations by WIRO
  86. GRB 050820B: Swift XRT position
  87. GRB050820B: Planned XMM-Newton observation
  88. GRB050820B: Refined analysis of the Swift-BAT burst
  89. GRB050820B: BAT-Swift detection of a bright GRB
  90. Swift/UVOT photometry of GRB050820
  91. GRB050820: refined XRT analysis
  92. GRB 050820: Early RAPTOR detections
  93. GRB 050820 Swift-BAT refined analysis
  94. GRB 050820: P60 Temporal Decay Index
  95. GRB 050820: High Resolution Spectroscopy from Keck
  96. GRB050819: refined XRT analysis
  97. GRB050819: RTT150 optical observations
  98. GRB 050820: Swift detection of a GRB
  99. GRB050820: Optical afterglow from P60
  100. GRB 050819 Swift-BAT refined analysis

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