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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"

7408 results found.

  1. GRB 050509b: Optical Counterpart Candidate
  2. GRB 050505 - Faulkes Telescope North observations
  3. GRB050505: Infrared observations
  4. GRB050505: AAVSO observations
  5. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  6. GRB050505: Optical Afterglow Candidate
  7. GRB 050416b:Swift XRT afterglow upper limits
  8. GRB 050416b:Swift XRT afterglow upper limits
  9. GRB050502b: Afterglow Confirmation: Correction to OT Coordinates
  10. GRB050502b: Afterglow Confirmation
  11. GRB050502A: Optical Observations
  12. Swift UVOT refined analysis
  13. GRB 050502: Confirmed variability of the afterglow candidate +
  14. GRB050502 - Correction on the Optical Candidate from the Liverpool
  15. GRB050502 - Optical Candidate from the Liverpool Telescope
  16. GRB 050421: NIR observations
  17. GRB 050416b: Tentative Swift XRT Position
  18. GRB050416: P200 NIR Observations
  19. GRB 050416: Swift XRT Position
  20. GRB 050416: Radio observations
  21. GRB050416: P60 Afterglow Candidate
  22. GRB 050412 : XingLong optical observation
  23. GRB 050408: Subaru Observations
  24. GRB 050408 Optical Observations
  25. GRB 050408: Magellan astrometry and photometry
  26. GRB 050408: First Optical observations with TFOSC at the RTT150
  27. GRB 050408 optical candidate
  28. Swift-UVOT Optical Counterpart Candidate to XRF 050406
  29. GRB 050401 Optical Observations
  30. GRB050402: XDSS counterpart
  31. GRB050401: ROTSE-III Detection of Prompt Optical Counterpart
  32. GRB 050401: Optical afterglow confirmed
  33. GRB 050401: Optical afterglow candidate
  34. GRB 050319 R band observations
  35. GRB 050319: NIR afterglow candidate
  36. GRB 050319:Near IR afterglow
  37. GRB050319: BR optical photometry
  38. GRB 050319 : Confirmation of optical afterglow decay
  39. GRB 050315, SMARTS optical afterglow decay
  40. GRB050316: MASTER optical observations
  41. GRB 050315, SMARTS optical/IR afterglow observations
  42. GRB 050315: Absorption redshift
  43. GRB 050306: Radio Observations
  44. GRB 050306: Confirmation of X-ray afterglow
  45. GRB 050309, Early optical limits from RAPTOR
  46. GRB 050306: CORRECTION to date of observation
  47. GRB 050306: R-band observations
  48. GRB 050306: No Swift UVOT Optical Counterpart Detected
  49. GRB 050306: REM optical-infrared observations
  50. GRB 050306: Possible X-ray Afterglow Position from the Swift
  51. GRB 050126: Confirmation of the NIR afterglow candidate
  52. GRB 050219b: candidate NIR afterglow
  53. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  54. GRB 050215B: Radio Observations
  55. GRB 050215b: XRT confirmation of IR afterglow candidate
  56. GRB050215b: P60 Optical Observations
  57. GRB 050215b: Swift XRT Source Variability
  58. GRB 050215B: candidate afterglow
  59. GRB 050124: Radio Observations
  60. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  61. GRB 050126: Radio Observations
  62. GRB 050128: Swift XRT prompt afterglow position
  63. GRB 050123 : I-band follow-up observation
  64. GRB041223: decay of the afterglow
  65. GRB041223: optical and NIR observations with REM
  66. GRB 041219 : optical follow-up observations
  67. Deep RAPTOR observations during GRB 041219
  68. GRB041218: Continued P60 Optical Observations
  69. GRB 041219: Infrared Afterglow Candidate
  70. GRB 041219: Infrared Afterglow Candidate
  71. GRB 041217: PROMPT Observations
  72. GRB041218: optical observations
  73. GRB 041218; optical candidate
  74. GRB 041218: Optical observations
  75. GRB041211, Faulkes Telescope optical observation
  76. GRB041006: Fading X-ray Afterglow Observed with Chandra
  77. GRB 041006 : Optical follow-up observation at TAROT
  78. GRB041006: Fading of optical afterglow candidate
  79. GRB 041006 : Optical follow-up observation at KISO
  80. GRB 041006: Finding chart
  81. GRB 041006: Optical afterglow candidate
  82. radio observations, GRB 040924
  83. GRB040924,optical observation
  84. GRB 040924: detection of possible host galaxy by Subaru
  85. GRB040924, RTT150 optical observation
  86. GRB040924: Afterglow magnitude at t=17.5hr
  87. GRB040924 : Optical candidate observations at Lulin observatory
  88. GRB040924 : Optical candidate observations at Lulin observatory
  89. GRB 040924: Subaru NIR observation
  90. GRB040924: Optical afterglow properties
  91. IPN triangulation of GRB040924 (H3564)
  92. GRB040924 (H3564): Optical afterglow candidate
  93. XRF 040912: Radio Observations
  94. XRF 040916: Radio Observations
  95. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  96. XRF040916: continuing decay of OT
  97. TAROT Observations of GRB 040916 (HETE #3558)
  98. GRB040912(=H3557): Candidate Optical Afterglow
  99. XRF040916, optical observations
  100. XRF040916: Optical Transient Candidate by Subaru

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