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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 050701
  2. GRB 050701, optical observations
  3. GRB 050408: ARC 3.5-meter NIR Observations
  4. GRB 050701: Refined XRT analysis
  5. Swift UVOT observations of GRB 050701
  6. GRB050701: Swift-BAT Refined analysis
  7. GRB 050701: Swift XRT afterglow position
  8. Swift trigger 143708 is really GRB 050701
  9. GRB 050607, radio observations
  10. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  11. GRB 050626 - Correction to GCN 3552
  12. GRB 050626 - a long GRB detected with INTEGRAL
  13. GRB 050525A: Swift Late-Time Decay Rate
  14. GRB050525a: HST Observations
  15. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  16. H3804: A Possible New XRB Detected by HETE
  17. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  18. XRF 050509c: Optical monitoring
  19. Konus-Wind observation of an intermediate burst from SGR 1806-20
  20. IBAS Alert #2512 is NOT a GRB
  21. XRF050509c: Radio Detection
  22. GRB 050416(a): Host Galaxy Redshift Determination
  23. GRB 050607: MDM Observation
  24. GRB 050607 optical decay
  25. GRB 050607: RTT150 optical observations
  26. GRB050607: refined analysis of prompt REM observations
  27. Swift/UVOT observations of GRB050607
  28. GRB 050607 : Lulin R-band observation
  29. GRB 050607: PROMPT VRcIc Observations
  30. GRB 050607: RAPTOR-S Early Optical Limits
  31. GRB050607: KAIT optical limits
  32. GRB 050525a, Mid-Infrared Observations
  33. GRB 050607: Optical decay and spectral slope
  34. GRB 050607: MDM Observations
  35. GRB050607,optical observation
  36. GRB 050607 - XRT refined data analysis
  37. Optical Afterglow of GRB 050607
  38. GRB050607 optical limit by "Pi of the Sky"
  39. GRB050607: Swift Detection of a long GRB
  40. GRB050607: P60 Observations
  41. GRB050607: prompt REM observations
  42. GRB 050603: prediction of t_break
  43. Limits on a SN in the field of GRB 050509b
  44. GRB 050603: Redshift
  45. GRB 050603 - XRT data analysis of the first day
  46. Konus-Wind observation of GRB 050603
  47. GRB 050603: Analysis of UVOT data
  48. GRB050603: Fading Afterglow observed by Swift UVOT
  49. GRB050603, submillimetre observations
  50. GRB 050603: Swift XRT Position
  51. GRB050603: Radio Detection
  52. GRB 050603: Swift-BAT refined analysis of a long three-spiked burst
  53. GRB 050603: Afterglow Identification from LCO
  54. GRB 050603: INTEGRAL shows it is not a short GRB
  55. Swift/BAT Detection of GRB050603
  56. GRB 050408: jet break in the XRT light curve
  57. GRB 050525a, infrared observations
  58. GRB 050525a, SMARTS optical/IR afterglow observations
  59. GRB050528, XRT observations
  60. Correction to GCN Circ 3502 on GRB 050528
  61. GRB050528: updated Liverpool Telescope limits
  62. Swift-BAT GRB 050528: a soft burst
  63. Update on Swift-BAT GRB 050528 (Trigger 130679)
  64. GRB050528: BOOTES optical candidate (retraction)
  65. GRB050504: Ashra-P2/3 monitor and Ashra-AFT response
  66. GRB050528: BOOTES optical candidate
  67. Possible GRB050528: no candidate from Liverpool Telescope
  68. Swift-BAT detection of possible GRB 050528
  69. GRB050525a: Radio Observations
  70. GRB 050509b: refined XRT/Chandra afterglow position analysis
  71. GRB 050525: RTT150, Optical observations
  72. GRB050525a: optical upper limits
  73. GRB 050525a: SARA Observations
  74. GRB 050525B: Swift-BAT observations
  75. GRB 050525: MITSuME Optical Observation in VRI
  76. GRB 050525a: MDM Observations
  77. GRB050525A,optical observation
  78. GRB 050525 : Lulin optical afterglow observations
  79. GRB050525: Super-LOTIS observations
  80. GRB 050525, spectral lag pseudo-redshift
  81. GRB 050525a: Gemini/GMOS Spectra
  82. GRB050306: optical afterglow not confirmed
  83. GRB 050525: BART optical observation
  84. GRB 050525A: BOOTES simultaneous optical observations
  85. GRB 050525A: Swift-BAT refined analysis
  86. GRB050525: Optical observations
  87. GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
  88. GRB 050525: pseudo-redshift
  89. Swift/UVOT UV and optical detections of GRB 050525
  90. Konus-Wind observation of GRB 050525
  91. GRB 050525: TAROT observations of the early afterglow
  92. INTEGRAL detection of GRB 050525
  93. GRB 050525, infrared observations
  94. GRB 050525: Optical observation
  95. GRB 050525: observatons of the optical afterglow
  96. GRB050525: ROTSE-III Refined Analysis
  97. GRB 050525 - Very Bright, Not Short
  98. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  99. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  100. XRF050522: NIR observations of XRT candidate

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