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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"

2707 results found.

  1. Possible radio detection of GRB 071021 with the VLA
  2. GRB 071021: possible high-z burst
  3. GRB071018: Correction to the title of the GCN 6936
  4. GRB 071018: Possible OT from Xinglong TNT observation
  5. GRB 071010A: Late-time Keck/LRIS photometry - possible host galaxy and jet break
  6. GRB 071018, Swift-BAT refined analysis
  7. GRB 071018?: Swift detection of a possible burst
  8. GRB 071013: 3rd TLS Epoch - constraints on variability
  9. GRB 071013: TLS 2nd epoch - Kornienko candidate constant
  10. GRB 071010B possible optical transient
  11. GRB 070810B: further XRT analysis
  12. GRB 071003: Keck spectroscopy
  13. GRB 071003: Possible rebrightening
  14. GRB 071003: Keck HIRES spectroscopy
  15. GRB 071003: MARGE Observations
  16. GRB070925: Swift-XRT Afterglow confirmation
  17. GRB 070917: Confirmation of the X-ray afterglow
  18. Swift Status and XRT Calibration Uncertainties
  19. GRB 070913: Swift-XRT detection of the possible X-ray afterglow
  20. Observations of possible TAROT GRB transient near IC 4779
  21. Las Campanas observations of possible TAROT GRB transient near IC
  22. Orphan GRB candidate in IC 4779 at TAROT La Silla observatory
  23. Swift observatory off line
  24. GRB 070810A: Continued Keck Imaging
  25. GRB 070810B: Keck spectroscopy of possible host galaxies
  26. GRB 070810B: XRT refined analysis
  27. GRB070810B: Optical observations with KANATA
  28. GRB 070810B: Swift detection of a short burst
  29. GRB 070809: Keck Imaging
  30. GRB 070810: Swift detection of a burst
  31. GCN Swift XRT update position notices and enhanced position circulars
  32. GRB070612A: Radio upper limit from GMRT
  33. GRB 070729: LCO optical imaging
  34. Four radio sources in Swift-XRT error box of GRB 070724
  35. GRB 070721: Swift detection of a possible burst
  36. Swift detection of a possible burst (Trigger 284850)
  37. GRB 070611: VLT observations
  38. GRB 070628: Swift XRT refined analysis
  39. GRB 070628: Swift detection of a possible burst
  40. GRB 070612A: Second Epoch WSRT Radio Observations
  41. GRB 070621: VLT optical observations
  42. GMRT upper limit of GRB 070610/SWIFT J195509.6+261406 in 610 MHz
  43. GRB070612A: Gemini Spectroscopic Redshift
  44. GRB 070616: Swift XRT refined circular
  45. GRB 070612A: Possible WSRT Radio Detection
  46. Swift XRT observations of the INTEGRAL burst GRB070615: Possible
  47. GRB 070612A: P60 Confirmation of Afterglow and An Underlying, Nearby
  48. SWIFT J195509.6+261406 / GRB 070610: SWIFT continued observations
  49. GRB 070612A: SARA detection of possible OT
  50. GRB 070610: SARA upper limit
  51. GRB 070610: Swift-XRT refined analysis
  52. GRB 070611, Swift-BAT refined analysis
  53. GRB 070419A, deep LBT photometry and possible supernova detection
  54. GRB 070529, Swift-BAT refined analysis
  55. GRB 070521 Milagro GeV/TeV Observations
  56. GRB 070521: Subaru observations and possible host detection
  57. GRB 070520A: Subaru Observations
  58. GRB 070517: Gemini optical imaging
  59. GRB 070510: Swift detection of a possible burst
  60. GRB 070508: Multicolor optical observations and possible redshift limit
  61. GRB 070507: Swift detection of a possible cosmic ray shower event or a possible burst
  62. GRB070429B: possible host galaxy detection
  63. GRB 070429A: Swift XRT refined analysis
  64. GRB 070429B: ROTSE-III Optical Limits
  65. GRB 070429B: Swift detection of a short burst
  66. Trigger 276045: Swift detection of a possible burst
  67. GRB 070411: TLS data shows plateau, flares
  68. GRB 070406: Astrometrically Refined XRT Position, Unfading Source
  69. GRB 070406: Bright galaxy in XRT error circle is a quasar
  70. Short GRB 070406 - Possible Bright Host Galaxy
  71. GRB 070406: Swift XRT Team analysis - Possible X-ray counterpart
  72. IPN triangulation of GRB070402
  73. UVOT observations of GRB070330
  74. GRB 070311: Optical Brightening
  75. GRB 070306: possible emission-line redshift
  76. GRB 070309: variability of the XRT afterglow candidate
  77. GRB 070311: MDM Optical Follow-up
  78. GRB 070311: PAIRITEL confirmation of variability of REM candidate
  79. GRB 070311: REM candidate afterglow
  80. GRB070309: Swift/XRT possible afterglow detection
  81. GRB 070125: X-ray light curve analysis
  82. GRB070227: possible X-ray afterglow detection
  83. GRB 920925C: optical afterglow candidate
  84. VLA observation of GRB 070223
  85. GRB070224: Swift-XRT Refined Analysis
  86. GRB 070223: Swift-XRT Refined Analysis
  87. GRB 070223: Liverpool Telescope Possible Afterglow Candidate
  88. GRB 070125 observations with the GMRT
  89. GRB 070208: MDM Optical Decay
  90. GRB070126: Swift-XRT Observation
  91. GRB 070125: optical observation
  92. GRB 070129, Swift-BAT refined analysis of a particularly long
  93. GRB 070126: VLT observations
  94. GRB070126: Swift-XRT possible detection of an afterglow
  95. Possible GRB 070126: Swift/UVOT Upper Limit
  96. GRB070125: Swift-XRT Refined Analysis
  97. GRB 070126?: Swift detection of a possible burst
  98. GRB 070110: Continued Detection and Request for Ground Followup
  99. GRB 070110: Ep,i - Eiso correlation
  100. Trigger 255685: Swift detection of a possible burst

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