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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"

27397 results found.

  1. GRB030324 optical observation
  2. GRB030324, optical observations
  3. GRB030324, optical observations
  4. GRB 030324: TAROT optical observations
  5. GRB 030324 (HETE #2641): Optical observations
  6. GRB030324, Optical Observations
  7. VLT/FORS2 spectra of GRB 030323
  8. GRB030323, ROTSE-III detection of possible optical counterpart
  9. GRB030323, optical observations
  10. GRB030324, BVRcIc field photometry
  11. GRB030323, possible optical counterpart
  12. GRB030323, BVRcIc field calibration
  13. GRB 030324 optical observations
  14. GRB 030324, optical observations
  15. GRB 030227: Optical limit at RIKEN
  16. Chandra detection of the X-ray afterglow of GRB 030226
  17. 030302: NOT A GRB
  18. 030228: NOT A GRB
  19. GRB 030228, optical observations
  20. GRB 030226: R band polarimetric observations
  21. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  22. GRB 030226 simultaneous optical observations
  23. GRB030226: Candidate optical afterglow
  24. IPN triangulation of GRB030215C (annulus)
  25. GRB 030115, simultaneous observations by BOOTES-1
  26. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  27. Distribution of INTEGRAL SPI-ACS triggers
  28. GRB030115: TAROT optical observations
  29. GRB 030115, no optical candidate
  30. IPN triangulation of GRB030101 (two large error boxes)
  31. GRB021211: Measurement of Early Time Afterglow
  32. GRB021204: Kiso Observations
  33. GRB 021211, R- and I-band observations
  34. GRB021211, OT at 108 s
  35. HETE 2493: Optical observations
  36. HETE 2493: Optical candidate
  37. GRB 021204: Optical Observations at RIKEN
  38. GRB 021201: BOOTES simultaneous optical observations
  39. GRB 021112: RAPTOR Observations
  40. GRB021104: Optical Observations
  41. SGR1900+14 activity, November 2-4, 2002
  42. GRB021104: possible optical afterglow
  43. GRB 021016, optical observations
  44. GRB 021004: VRI observations at TNG: possible break
  45. GRB 021008, optical observations
  46. IPN triangulation of GRB021014 (large error box)
  47. GRB 021004: Additional V-band Polarimetric Observations
  48. GRB 021004: V-band Polarimetric Observations
  49. GRB 021004: Optical observations at RIKEN
  50. GRB 021004, SPM optical observations
  51. GRB021004: optical observations at Nyrola
  52. GRB021004: Optical Afterglow
  53. GRB 020903: Optical observations at RIKEN
  54. XRF 020903: Supernova
  55. IPN triangulation of GRB020914
  56. GRB020903(=H2314): An X-Ray Flash Localized by HETE
  57. INTEGRAL GRBs added to GCN
  58. GRB020812: optical observation
  59. Second epoch K band imaging of GRB 020819
  60. K band observation of GRB 020819
  61. HETE 2275: Optical observations
  62. Polarimetry of GRB020813: evidence for variability
  63. GRB020812: optical observations
  64. GRB020813: Early Time Magnitude
  65. GRB020813, optical observations
  66. Early Time Limits for GRB020813
  67. GRB 020813 Afterglow Observations; Possible break
  68. GRB 020813 multiband optical observations
  69. GRB020813: optical afterglow
  70. GRB020813: Fading of Candidate OT
  71. GRB020813: Candidate Optical Afterglow
  72. GRB 020812 optical observation
  73. GRB020801, optical afterglow candidate
  74. GRB020625 (=H2081): A Long Burst Localized by HETE
  75. HETE #2081: Optical observations
  76. GRB 020531, simultaneous optical observations
  77. GRB020321 : Optical observations.
  78. GRB 020410, optical observations
  79. GRB 020331: Candidate Optical Afterglow
  80. GRB 020322: BeppoSAX observations of the X-ray afterglow
  81. SN 2002ap - peak brightness date (SN/GRB?)
  82. GRB020321: a faint BeppoSAX detection
  83. GRB020317, optical observations
  84. GRB020305, optical observations
  85. GRB020124, optical observations
  86. HETE 1896: Optical observations
  87. GRB011130 (=XRF011130), Optical Observations
  88. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  89. GRB 011030: K-band observations
  90. The X-ray Flash 011030 ('GRB 011030')
  91. GRB 011019 optical observation
  92. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  93. GRB 010921: The afterglow of HETE #1761
  94. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  95. Optical Observations of the field of HETE trigger #1793/GRB 011012?
  96. GRB010921 Optical Observations
  97. HETE Trigger #1760 (GRB 010920B?): new optical source = asteroid
  98. HETE Trigger #1760 (GRB 010920B?): a new optical source
  99. HETE Trigger #1759 (GRB 010920?) optical observations
  100. BeppoSAX/GRBM detection of GRB 010801

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