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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"

43621 results found.

  1. GRB060108: P200 Ks Observations
  2. GRB 060108: early UKIRT K-band observations
  3. Swift UVOT correction to GCN 4455
  4. GRB 060109: Swift Detection of a long burst
  5. GRB 060108: a dark burst?
  6. GRB 060108: Refined XRT analysis
  7. GRB 060108: VLT J-band observations
  8. GRB 060108: Swift/UVOT upper limits
  9. GRB 060105: quick look analysis of the Suzaku/XIS afterglow observation
  10. GRB060108: SDSS pre-burst observations
  11. GRB060108: Faulkes Telescope observation
  12. GRB 060108: Refined analysis of the Swift-BAT burst
  13. GRB 060108: Swift XRT position
  14. GRB060108: Swift detection of its 100th GRB
  15. GRB 060105: pseudo-z from spectral parameters of the prompt emission
  16. GRB 060105: Radio observations
  17. GRB 060105: MDM Observation
  18. Konus-Wind observation of GRB 060105
  19. GRB 060105: Swift/UVOT upper limits
  20. GRB 060105: BAT refined analysis
  21. GRB 060102 - no XRT afterglow
  22. GRB 060105: XRT refined analysis
  23. GRB060105, optical observation
  24. GRB060105: Swift detection of a bright long burst
  25. Swift-BAT trigger 175653 is not an astrophysical source
  26. GRB 060102: MDM Observation
  27. Swift-BAT trigger 175653 is probably not a GRB
  28. GRB 060102: Swift-BAT refined analysis
  29. Time Correction to GRB 060102
  30. GRB 060102: Swift-BAT detection of a burst
  31. GRB051211B: optical observations
  32. GRB051227: SARA Observations
  33. GRB 051221B: Optical Observations with Kuiper 1.54m
  34. GRB 051227: Likely host galaxy underlying afterglow position
  35. GRB 051227: optical observation
  36. GRB051221B: Radio observations
  37. GRB 051221A: VLA Radio Observations
  38. GRB051227: Radio Observations
  39. GRB 051227: Confirmed fading from Gemini observations
  40. GRB051227: further analysis of VLT images
  41. GRB 051227: optical afterglow
  42. GRB 051227: Swift/UVOT Upper Limits (Possible U-band
  43. GRB 051227: Gemini observations
  44. GRB 051227: Keck Spectroscopy
  45. GRB 051227: Magellan r'-band Imaging/Astrometry
  46. GRB 051227: refined analysis of VLT images
  47. GRB 051227: P60 Observations
  48. GRB 051227: MDM Observation
  49. GRB 051227: R-band object in the XRT error circle
  50. GRB 051227: Joint Swift-HETE Spectral Analysis
  51. GRB 051227: XRT refined analysis
  52. GRB 051227: Further analysis of the Swift-BAT burst
  53. GRB 051227: Refined analysis of the Swift-BAT burst
  54. GRB051227: SDSS pre-burst observations
  55. GRB 051227, optical observation
  56. GRB 051227: Swift detection of a burst
  57. GRB051117B: optical observation
  58. IBAS_alert n. 2719 : not a real GRB
  59. Konus-Wind observation of GRB 051221A
  60. GRB051221A: Suzaku WAM observation of the prompt emission
  61. GRB 051221A: MDM Optical Observations
  62. GRB051016: analysis of the XMM-Newton observation
  63. GRB 051221A: Detection at 251nm with Swift UVOT
  64. GRB 051221A: Chandra Afterglow Position
  65. GRB 051221A: Refined spectral and temporal analysis of the Swift-BAT short hard burst
  66. GRB 051221B: ROTSE-III Optical Limits
  67. GRB 051221B: TAROT optical limits
  68. GRB 051221A: WSRT Radio Observations
  69. GRB 051221: Redshift from Gemini
  70. GRB 051221: Continued fading of optical afterglow
  71. GRB 051221B: Refined analysis of the Swift-BAT burst
  72. Possible GRB 051221B: MDM Optical Detection
  73. GRB 051221A: RAPTOR Fading Counterpart Constraint
  74. GRB 051221B: BOOTES optical observations.
  75. Possible GRB 051221B: Swift XRT position
  76. GRB 051211A: Evidence This Is a Short Burst from Analysis of Spectral
  77. Swift-BAT detection of a possible burst
  78. GRB 051221: Discovery of fading optical afterglow
  79. GRB 051221: Swift XRT refined analysis
  80. GRB 051221: Swift/UVOT upper limits
  81. GRB 051221: Possible nearby cluster
  82. GRB 051221: No variability in Gemini data
  83. GRB 051221: Correction to GCN #4368
  84. GRB 051221: Gemini observations
  85. GRB 051221: Improved astrometry of the IR counterpart
  86. GRB051221: K-band source
  87. GRB 051221: XRT position
  88. GRB 051221: Refined analysis of the Swift-BAT short hard burst
  89. GRB 051221: IR Observations at GRB+1hr
  90. GRB 051221: Swift detection of a bright short burst
  91. Refined analysis of the SWIFT J1626.6-5156
  92. Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156
  93. Refined analysis of the Swift-BAT detection of the RS CVn star II Peg
  94. GRB051211A (=H3979): Refined Analysis
  95. GRB 051211B: optical afterglow
  96. Swift detection of an RS CVn flare star
  97. GRB051211A: possible optical candidate
  98. Swift Trigger 172767 is not a GRB
  99. GRB 051215: near-infrared observations
  100. GRB051215 - SDSS pre-burst observations

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