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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"

36162 results found.

  1. GRB 050904: Environmental Constraints
  2. GRB 050904: Possible High-Redshift GRB
  3. GRB 050904: SOAR/PROMPT Observations
  4. GRB 050904: TAROT optical limits
  5. Swift-BAT triggers 153461-153465 are not GRBs
  6. GRB 050824: MDM Observations
  7. GRB 050827: Swift XRT preliminary analysis results
  8. IBAS Alerts 2641 and 2642: not a real GRB
  9. Swift Trigger #152652 is not a GRB
  10. GRB 050827 : OSN 1.5m optical observations
  11. GRB 050827: P200 NIR Observations
  12. GRB 050827: Optical Limit
  13. GRB 050827: XRT possible afterglow detection
  14. GRB 050826 : Lulin R band observation
  15. GRB050824: Maidanak optical limits
  16. GRB050820A: RTT150 optical observations
  17. GRB050827: RTT150 optical observations
  18. GRB 050827: Swift-BAT refined analysis
  19. GRB 050826: Optical Candidate
  20. GRB050824, HETE-2 Observation
  21. GRB 050826: Swift XRT preliminary analysis results
  22. GRB 050826: BAT refined analysis
  23. GRB050824: First 2 hours of power low optical decay?
  24. GRB 050826: Swift XRT position
  25. GRB050826: Swift-BAT detection of a long burst
  26. GRB050824: MASTER final analysis of the OT observations
  27. Possible GRB050825:MASTER optical observations
  28. Swift-BAT trigger 152038 is definitely not a GRB
  29. Swift-BAT trigger 152038 is probably not a GRB
  30. GRB050824: decay of the XRT light curve and updated X-ray spectrum
  31. GRB050824, I-band imaging
  32. GRB050824: Radio Observations
  33. GRB 050824: Spectroscopic redshift from the VLT
  34. GRB 050822: refined XRT analysis
  35. GRB 050824: XRT refined analysis and possible afterglow detection
  36. GRB 050824: BAT refined analysis of a soft weak burst
  37. GRB050824: MASTER:OT decay
  38. GRB050824: MASTER observation OT
  39. GRB050805a: MASTER optical candidat
  40. GRB 050824: ROTSE-III Optical Limits
  41. GRB050824: Swift-BAT detection of a burst
  42. GRB 050824 optical candidate
  43. GRB050820A: RTT150 optical observations
  44. GRB050820a: PROMPT RcIc Observations
  45. GRB050815: Maidanak optical observation
  46. XRF050509c: Radio upper limits from GMRT
  47. VLT/UVES spectroscopy of GRB050820
  48. GRB 050820A BAT observations of second, larger episode of emission
  49. GRB050813: Maidanak I-band observations
  50. GRB 050822: Swift-BAT refined analysis
  51. GRB050525, GRB050607, GRB050802 BVRcIc field photometry
  52. GRB050820B at FRAM
  53. GRB050820A: RTT150 optical observations
  54. GRB 050820a - corrections to GCN 3846
  55. Swift/UVOT UV Photometry of GRB 050820B
  56. GRB 050822: ROTSE-III Prompt Optical Limits
  57. GRB 050822: Swift detection of a long burst
  58. Correction to Eiso calculation in GCN 3835 on GRB 050820A
  59. GRB050820A: Radio Observation
  60. GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
  61. GRB050820a BVRcIc field photometry
  62. GRB 050820a: NIR Observations by WIRO
  63. GRB 050820B: Swift XRT position
  64. GRB050820B: Refined analysis of the Swift-BAT burst
  65. GRB050820B: BAT-Swift detection of a bright GRB
  66. GRB050820: refined XRT analysis
  67. GRB 050820: Early RAPTOR detections
  68. GRB 050820 Swift-BAT refined analysis
  69. GRB 050820: P60 Temporal Decay Index
  70. GRB 050820: High Resolution Spectroscopy from Keck
  71. GRB050819: RTT150 optical observations
  72. GRB 050820: Swift detection of a GRB
  73. GRB 050819 Swift-BAT refined analysis
  74. GRB050819: Swift XRT position
  75. GRB050819: Swift-BAT detection of a weak burst
  76. Swift-BAT trigger 150993 is not a GRB
  77. Swift Trigger 150823 is HETE J1900.1-2455
  78. GRB 050817: Optical observations
  79. GRB 050815: Radio Observation
  80. GRB050814: Radio Observation
  81. GRB050817: Negative Optical Observations
  82. GRB 050814: continued fading
  83. GRB 050813: Radio Observations
  84. GRB050815: Refined analysis of the Swift-BAT burst
  85. GRB 050815: ROTSE-III Optical Limits
  86. GRB050815: Swift XRT afterglow localization
  87. GRB 050730: Third Epoch WSRT Radio Observations
  88. GRB050814: Fading red source
  89. GRB 050813: Gemini Spectra Revisited
  90. GRB 050813: Non-fading of afterglow candidate
  91. GRB 050814: XRT refined analysis
  92. GRB050814: Refined analysis of the Swift-BAT burst
  93. GRB050813: Gemini Imaging
  94. GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
  95. GRB 050814: Swift XRT Afterglow Localization
  96. GRB 050814: Swift detection of a burst
  97. GRB 050813: Magellan detection of a high redshift galaxy cluster
  98. GRB050813: RTT150 optical observations
  99. GRB 050813: I-band observations
  100. GRB050813, SDSS pre-burst observations

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