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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. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  2. GRB 050626 - Correction to GCN 3552
  3. GRB 050626 - a long GRB detected with INTEGRAL
  4. GRB 050525A: Swift Late-Time Decay Rate
  5. GRB050525a: HST Observations
  6. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  7. H3804: A Possible New XRB Detected by HETE
  8. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  9. XRF 050509c: Optical monitoring
  10. Konus-Wind observation of an intermediate burst from SGR 1806-20
  11. IBAS Alert #2512 is NOT a GRB
  12. XRF050509c: Radio Detection
  13. GRB 050416(a): Host Galaxy Redshift Determination
  14. GRB 050607: MDM Observation
  15. GRB 050607 optical decay
  16. GRB 050607: RTT150 optical observations
  17. GRB050607: refined analysis of prompt REM observations
  18. Swift/UVOT observations of GRB050607
  19. GRB 050607 : Lulin R-band observation
  20. GRB 050607: PROMPT VRcIc Observations
  21. GRB 050607: RAPTOR-S Early Optical Limits
  22. GRB050607: KAIT optical limits
  23. GRB 050525a, Mid-Infrared Observations
  24. GRB 050607: Optical decay and spectral slope
  25. GRB 050607: MDM Observations
  26. GRB050607,optical observation
  27. GRB 050607 - XRT refined data analysis
  28. Optical Afterglow of GRB 050607
  29. GRB050607 optical limit by "Pi of the Sky"
  30. GRB050607: Swift Detection of a long GRB
  31. GRB050607: P60 Observations
  32. GRB050607: prompt REM observations
  33. GRB 050603: prediction of t_break
  34. Limits on a SN in the field of GRB 050509b
  35. GRB 050603: Redshift
  36. GRB 050603 - XRT data analysis of the first day
  37. Konus-Wind observation of GRB 050603
  38. GRB 050603: Analysis of UVOT data
  39. GRB050603: Fading Afterglow observed by Swift UVOT
  40. GRB050603, submillimetre observations
  41. GRB 050603: Swift XRT Position
  42. GRB050603: Radio Detection
  43. GRB 050603: Swift-BAT refined analysis of a long three-spiked burst
  44. GRB 050603: Afterglow Identification from LCO
  45. GRB 050603: INTEGRAL shows it is not a short GRB
  46. Swift/BAT Detection of GRB050603
  47. GRB 050408: jet break in the XRT light curve
  48. GRB 050525a, infrared observations
  49. GRB 050525a, SMARTS optical/IR afterglow observations
  50. GRB050528, XRT observations
  51. Correction to GCN Circ 3502 on GRB 050528
  52. GRB050528: updated Liverpool Telescope limits
  53. Swift-BAT GRB 050528: a soft burst
  54. Update on Swift-BAT GRB 050528 (Trigger 130679)
  55. GRB050528: BOOTES optical candidate (retraction)
  56. GRB050504: Ashra-P2/3 monitor and Ashra-AFT response
  57. GRB050528: BOOTES optical candidate
  58. Possible GRB050528: no candidate from Liverpool Telescope
  59. Swift-BAT detection of possible GRB 050528
  60. GRB050525a: Radio Observations
  61. GRB 050509b: refined XRT/Chandra afterglow position analysis
  62. GRB 050525: RTT150, Optical observations
  63. GRB050525a: optical upper limits
  64. GRB 050525a: SARA Observations
  65. GRB 050525B: Swift-BAT observations
  66. GRB 050525: MITSuME Optical Observation in VRI
  67. GRB 050525a: MDM Observations
  68. GRB050525A,optical observation
  69. GRB 050525 : Lulin optical afterglow observations
  70. GRB050525: Super-LOTIS observations
  71. GRB 050525, spectral lag pseudo-redshift
  72. GRB 050525a: Gemini/GMOS Spectra
  73. GRB050306: optical afterglow not confirmed
  74. GRB 050525: BART optical observation
  75. GRB 050525A: BOOTES simultaneous optical observations
  76. GRB 050525A: Swift-BAT refined analysis
  77. GRB050525: Optical observations
  78. GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
  79. GRB 050525: pseudo-redshift
  80. Swift/UVOT UV and optical detections of GRB 050525
  81. Konus-Wind observation of GRB 050525
  82. GRB 050525: TAROT observations of the early afterglow
  83. INTEGRAL detection of GRB 050525
  84. GRB 050525, infrared observations
  85. GRB 050525: Optical observation
  86. GRB 050525: observatons of the optical afterglow
  87. GRB050525: ROTSE-III Refined Analysis
  88. GRB 050525 - Very Bright, Not Short
  89. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  90. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  91. XRF050522: NIR observations of XRT candidate
  92. XRF 050522: Swift XRT refined analysis
  93. XRF050522: Radio Observations
  94. Swift/UVOT observation of XRF 050522
  95. GRB 050509A: Further I-band imaging
  96. GRB050522,optical observation
  97. GRB050520,optical observation
  98. XRF 050522: Continued NIR P200 Monitoring
  99. RBO Observations of GRB050522
  100. GRB050509b: optical observations

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