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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: Radio Observations
  2. GRB 050904: Keck I-band Imaging
  3. GRB050906: P60 Observations
  4. GRB 050904: more VLT NIR observations
  5. GRB 050904: BOOTES early R-band observation
  6. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  7. GRB 050906: Bright galaxy in BAT error box
  8. GRB 050906: Swift/BAT Detection of a possible burst
  9. GRB 050904: More SOAR
  10. GRB 050904: photometric redshift
  11. GRB 050904: Swift/UVOT observations
  12. GRB 050904: Afterglow Astrometry
  13. GRB 050904: NIR object inside the XRT error box
  14. GRB 050904: early Swift XRT analysis results
  15. GRB 050904: SOAR YJ and PROMPT Ic Observations
  16. GRB 050904: BAT refined analysis of partial data set
  17. GRB 050904: TAROT optical measurements
  18. GRB050904: Optical Observations
  19. GRB 050904: Environmental Constraints
  20. GRB 050904: Possible High-Redshift GRB
  21. GRB 050904: SOAR/PROMPT Observations
  22. GRB050904: P60 Observations
  23. GRB 050904: TAROT optical limits
  24. GRB050904: Swift-BAT detection of a probable burst
  25. Swift-BAT triggers 153461-153465 are not GRBs
  26. Retraction of Swift-BAT trigger #153355
  27. GRB 050824: MDM Observations
  28. GRB 050827: Swift XRT preliminary analysis results
  29. IBAS Alerts 2641 and 2642: not a real GRB
  30. Swift Trigger #152652 is not a GRB
  31. GRB 050827 : OSN 1.5m optical observations
  32. GRB 050827: P200 NIR Observations
  33. GRB050827: Swift/UVOT upper limits
  34. GRB 050827: Optical Limit
  35. GRB 050827: XRT possible afterglow detection
  36. GRB 050826 : Lulin R band observation
  37. GRB050824: Maidanak optical limits
  38. GRB050820A: RTT150 optical observations
  39. GRB050827: RTT150 optical observations
  40. GRB 050827: Swift-BAT refined analysis
  41. GRB050827: Swift-BAT detection of a burst
  42. Subaru Observations of GRB050724
  43. GRB 050826: Optical Candidate
  44. GRB050824, HETE-2 Observation
  45. GRB 050826: Swift XRT preliminary analysis results
  46. GRB 050826: BAT refined analysis
  47. GRB050826: Swift/UVOT early upper limits
  48. GRB050824: First 2 hours of power low optical decay?
  49. GRB 050826: Swift XRT position
  50. GRB050826: Swift-BAT detection of a long burst
  51. GRB050824: MASTER final analysis of the OT observations
  52. Possible GRB050825:MASTER optical observations
  53. Swift-BAT trigger 152038 is definitely not a GRB
  54. GRB050824: CORRECTION to UVOT observing times
  55. Swift-BAT trigger 152038 is probably not a GRB
  56. GRB050824: Swift/UVOT detection of fading afterglow
  57. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  58. GRB050824, I-band imaging
  59. GRB050824: Radio Observations
  60. GRB 050824: Spectroscopic redshift from the VLT
  61. GRB 050822: refined XRT analysis
  62. GRB 050824: XRT refined analysis and possible afterglow detection
  63. GRB 050824: BAT refined analysis of a soft weak burst
  64. GRB050824: MASTER:OT decay
  65. GRB050824: MASTER observation OT
  66. GRB050805a: MASTER optical candidat
  67. GRB 050824: ROTSE-III Optical Limits
  68. GRB050824: Swift-BAT detection of a burst
  69. GRB 050824 optical candidate
  70. GRB050820A: RTT150 optical observations
  71. GRB050820a: PROMPT RcIc Observations
  72. GRB050815: Maidanak optical observation
  73. XRF050509c: Radio upper limits from GMRT
  74. VLT/UVES spectroscopy of GRB050820
  75. GRB050822: Swift/UVOT upper limits
  76. GRB 050820A BAT observations of second, larger episode of emission
  77. GRB050813: Maidanak I-band observations
  78. GRB 050822: Swift-BAT refined analysis
  79. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  80. GRB050820B at FRAM
  81. GRB050820A: RTT150 optical observations
  82. GRB 050820a - corrections to GCN 3846
  83. Swift/UVOT UV Photometry of GRB 050820B
  84. GRB 050822: ROTSE-III Prompt Optical Limits
  85. GRB 050822: Swift detection of a long burst
  86. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  87. GRB050820A: Radio Observation
  88. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  89. GRB050820a BVRcIc field photometry
  90. GRB050820B XMM-Newton observation
  91. GRB 050820a: NIR Observations by WIRO
  92. GRB 050820B: Swift XRT position
  93. GRB050820B: Planned XMM-Newton observation
  94. GRB050820B: Refined analysis of the Swift-BAT burst
  95. GRB050820B: BAT-Swift detection of a bright GRB
  96. Swift/UVOT photometry of GRB050820
  97. GRB050820: refined XRT analysis
  98. GRB 050820: Early RAPTOR detections
  99. GRB 050820 Swift-BAT refined analysis
  100. GRB 050820: P60 Temporal Decay Index

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