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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. GRB041218: Liverpool Telescope optical observations
  2. GRB041218: optical observations
  3. GRB041219: Confirmed NIR Afterglow
  4. GRB041218: Continued P60 Optical Observations
  5. Swift-BAT detection of the bright long burst GRB041219
  6. GRB 041218: Optical Observation
  7. GRB 041219: Infrared Afterglow Candidate
  8. GRB041219, BVRcIc field calibration
  9. GRB 041219: Infrared Afterglow Candidate
  10. GRB041218, BVRcIc field calibration
  11. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  12. GRB041219: P60 Optical Observations
  13. GRB 041219 - A long GRB detected by INTEGRAL
  14. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  15. GRB 041217: PROMPT Observations
  16. GRB041218: optical observations
  17. GRB041217: optical limit 30 min after GRB
  18. GRB 041218; optical candidate
  19. GRB 041218: Optical observations
  20. GRB 041217: LCO40 Optical Observations and Possible Candidates
  21. GRB 041218 - A long GRB detected by integral
  22. GRB041217: Optical Observations
  23. GRB041217: NIR and optical observations with REM
  24. GRB041217: P60 Optical Observations
  25. GRB041217: Infrared Observations
  26. GRB041217: The First GRB Located On-Board Swift
  27. GRB041211: Faulkes Telescope continued optical monitoring
  28. Optical Transient in Lynx not a GRB
  29. Optical transient (GRB?) in Lynx
  30. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  31. GRB041211: Continued P60 Observations
  32. GRB041211: RAPTOR observations
  33. GRB041211: Ashra Prototype optical observation
  34. GRB041211, Faulkes Telescope optical observation
  35. GRB041211, BVRcIc field calibration
  36. GRB041211,optical observation
  37. GRB 041211: Infrared Observations
  38. GRB 041211: KAIT observations
  39. GRB 041211: Optical follow-up in East Asian region
  40. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  41. GRB041211: P60 optical imaging
  42. GRB970815: Discovery of Optical Afterglow
  43. Distribution of IBAS Alerts for NON-GRB sources
  44. Triangulation of short GRB 041116 (large error box)
  45. GRB041015: Near-Infrared observations
  46. GRB 040924: Afterglow Color
  47. GRB 041006: GETS Optical Afterglow Observation
  48. Summary of the recent bursts from SGR 1806-20
  49. GRB 041006: Optical Observations
  50. GRB041006, late-time optical photometry
  51. GRB041015, optical observation in CrAO
  52. IBAS GRB Alert # 2034
  53. GRB041006: RTT150 Optical Observations
  54. GRB041015 : Multi epoch optical observations
  55. HST Observations: XRF 040701 and 040812
  56. Bright bursts from SGR1806-20
  57. GRB 041016: BOOTES-2 simultaneous observation
  58. GRB041006: RTT150 Optical Observations
  59. GRB041016,optical observation
  60. GRB 041016: Optical limits
  61. GRB 041016: Optical limits in V, R, I
  62. GRB 041016:Optical limit during first minute
  63. GRB041016: MASTER: Optical observations
  64. GRB 041015: Optical Observations at Rikubetsu
  65. GRB041006: Near Infrared observations
  66. GRB 041016: Optical limit
  67. GRB 041015 R band observations
  68. GRB040924, BVRcIc field calibration
  69. GRB041015: MASTER: Optical observations
  70. GRB041015,optical observation
  71. GRB041006: Fading X-ray Afterglow Observed with Chandra
  72. GRB 041015: Optical limit at Osaka University
  73. GRB041015 : Optical follow-up at Kiso
  74. GRB 041015 - A long GRB detected by INTEGRAL
  75. GRB 041006 R observations in Loiano
  76. GRB041006: VLT observations of the afterglow and host galaxy
  77. GRB041006: Optical observations and Potential host galaxy
  78. GRB041006, BVRcIc field calibration
  79. GRB 040924: VLT spectroscopy
  80. GRB 041006: SARA afterglow observations
  81. GRB041006, optical observation in CrAO
  82. Search for SN light in XRF 040912 with MEGACAM
  83. GRB 040916: Afterglow Color at Early Times
  84. GRB 041006 Optical afterglow observations
  85. IBAS GRB Alert # 2010
  86. GRB 041006: BR observations with VATT
  87. GRB 041006: Redshift confirmed
  88. GRB041006: Liverpool Telescope optical observations
  89. GRB 041006: Colour measurement
  90. GRB041006: break in the light curve
  91. GRB 041006: Radio Observations
  92. GRB041006, further submilllimetre observations
  93. GRB 041006 : optical follow-up observation at Lulin Observatory
  94. SUBJECT: GRB 041006 : Optical follow-up observation at TAROT
  95. GRB041006: Optical photometry and spectroscopy at TNG
  96. GRB 041006: presice astrometry
  97. GRB041006 (= H3570): Chandra Observations In Progress
  98. GRB 041006 : optical observation at Bisei
  99. GRB041006, optical I observation
  100. GRB041006 (=HETE3570): optical observations

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