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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"

32542 results found.

  1. GRB 041218: optical observations
  2. Very high activity of SGR 1806-20
  3. GRB 041219: Second Epoch WSRT Radio Observations
  4. GRB 041219: WSRT Radio Afterglow Detection
  5. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  6. GRB 041218: Optical observations
  7. GRB 041219 : optical follow-up observations
  8. Deep RAPTOR observations during GRB 041219
  9. GRB 041218 Optical Observations
  10. GRB 041219 Optical Observations
  11. GRB041219: Optical Afterglow Detection
  12. GRB041219: Continued NIR Observations
  13. GRB 041219: Radio Afterglow Detection
  14. GRB 041218 : Radio Observations
  15. GRB 041218: R-band optical observations
  16. GRB041218: Liverpool Telescope optical observations
  17. GRB041218: optical observations
  18. GRB041219: Confirmed NIR Afterglow
  19. Swift-BAT detection of the bright long burst GRB041219
  20. GRB 041218: Optical Observation
  21. GRB 041219: Infrared Afterglow Candidate
  22. GRB041219, BVRcIc field calibration
  23. GRB 041219: Infrared Afterglow Candidate
  24. GRB041218, BVRcIc field calibration
  25. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  26. GRB 041217: PROMPT Observations
  27. GRB041218: optical observations
  28. GRB041217: optical limit 30 min after GRB
  29. GRB 041218; optical candidate
  30. GRB 041218: Optical observations
  31. GRB 041217: LCO40 Optical Observations and Possible Candidates
  32. GRB041217: Optical Observations
  33. GRB041217: NIR and optical observations with REM
  34. GRB041217: Infrared Observations
  35. GRB041217: The First GRB Located On-Board Swift
  36. GRB041211: Faulkes Telescope continued optical monitoring
  37. Optical Transient in Lynx not a GRB
  38. Optical transient (GRB?) in Lynx
  39. GRB041211: Continued P60 Observations
  40. GRB041211, Faulkes Telescope optical observation
  41. GRB041211, BVRcIc field calibration
  42. GRB 041211: Infrared Observations
  43. GRB 041211: Optical follow-up in East Asian region
  44. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  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. GRB041006: RTT150 Optical Observations
  52. GRB041015 : Multi epoch optical observations
  53. GRB041006: RTT150 Optical Observations
  54. GRB 041016: Optical limits
  55. GRB 041015: Optical Observations at Rikubetsu
  56. GRB041006: Near Infrared observations
  57. GRB040924, BVRcIc field calibration
  58. GRB 041015: Optical limit at Osaka University
  59. GRB041015 : Optical follow-up at Kiso
  60. GRB 041006 R observations in Loiano
  61. GRB041006: VLT observations of the afterglow and host galaxy
  62. GRB041006: Optical observations and Potential host galaxy
  63. GRB041006, BVRcIc field calibration
  64. GRB 040924: VLT spectroscopy
  65. GRB 041006: SARA afterglow observations
  66. GRB041006, optical observation in CrAO
  67. Search for SN light in XRF 040912 with MEGACAM
  68. GRB 040916: Afterglow Color at Early Times
  69. GRB 041006 Optical afterglow observations
  70. GRB 041006: BR observations with VATT
  71. GRB 041006: Redshift confirmed
  72. GRB041006: Liverpool Telescope optical observations
  73. GRB 041006: Colour measurement
  74. GRB041006: break in the light curve
  75. GRB 041006: Radio Observations
  76. GRB 041006 : optical follow-up observation at Lulin Observatory
  77. GRB 041006 : Optical follow-up observation at TAROT
  78. GRB041006: Optical photometry and spectroscopy at TNG
  79. GRB 041006: presice astrometry
  80. GRB041006 (= H3570): Chandra Observations In Progress
  81. GRB 041006 : optical observation at Bisei
  82. GRB041006, optical I observation
  83. GRB041006 (=HETE3570): optical observations
  84. ROTSE-IIIa Observations of GRB 041006
  85. GRB041006, optical observation
  86. GRB041006, submillimetre observations
  87. GRB041006: MASTER optical observations
  88. GRB 041006: Optical decay
  89. GRB 041006 (=H3570): An X-Ray Rich GRB Localized in Real Time by HETE
  90. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  91. GRB041006: Fading of optical afterglow candidate
  92. GRB 041006 : Optical follow-up observation at KISO
  93. GRB 041006: Finding chart
  94. GRB 041006: Optical afterglow candidate
  95. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  96. XRF 020903: Observations of the Host Galaxy (authors)
  97. XRF 020903: Observations of the Host Galaxy
  98. GRB 040924: Second Epoch WSRT Radio Observations
  99. radio observations, GRB 040924
  100. Konus-Wind and Helicon-Coronas-F observations of GRB040924

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