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

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