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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"

45436 results found.

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

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