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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"

21800 results found.

  1. XRF 040701 - optical observations of the decaying Chandra source
  2. XRF040701: Second-Epoch Chandra Observations
  3. XRF040701: VLA Observations
  4. XRF040701: Magellan Spectroscopy of Chandra Source #2 Associated Galaxy
  5. XRF040701: First-Epoch Chandra Observations
  6. GRB040709 J,H-band observations
  7. GRB040624, optical observations
  8. XRF 040701, optical observations
  9. GRB 040624: optical observations
  10. Optical Observations of GRB040624
  11. GRB 040624: optical observations at TNG and VLT
  12. GRB 040624: R-band observations
  13. GRB 040624, optical observations
  14. GRB 030329: Rebrightening of hyperluminal ejecta.
  15. GRB040511: Retraction of redshift identification
  16. SGR 1806-20: no IR variability of the proposed counterparts
  17. SGR 1806-20, potential NIR counterpart
  18. GRB 040606: Optical observations
  19. GRB 030324: Detection and Color of Host Galaxy
  20. GRB 040511: NIR observations with REM
  21. GRB 040511: Second Epoch Optical Observations
  22. GRB 040511: Optical observations
  23. GRB 040511: Optical Observations
  24. GRB040511: Optical Observations
  25. GRB040511: Optical Observations
  26. GRB040422: optical observations at Xinglong Observatory
  27. GRB040422: optical observations at CrAO
  28. GRB040422, optical observations at Loiano
  29. GRB040422: optical and NIR observations at the VLT
  30. GRB 040403, deep optical observations
  31. GRB 040403: Optical Observations
  32. GRB 040403 Optical Observations
  33. GRB 040403: Optical observations
  34. GRB 040403: optical observations
  35. GRB 040403: Optical Observations
  36. GRB040323: NIR Observations and Variable Object
  37. GRB 031203: spectoscopic evidence for a 1998bw-like SN
  38. GRB 031203, possible supernova
  39. GRB 040228 Optical observations
  40. GRB 040223: Deep NIR NTT observations
  41. GRB 040223 : Optical observation (non-detection)
  42. GRB 040223, VLA observations
  43. GRB 040223: REM IJK Observations
  44. GRB031111, optical observations
  45. GRB031220: 2nd Chandra observation and X-ray afterglow candidate
  46. GRB031203: Chandra Observations
  47. GRB040106, follow-up radio observations
  48. SN 2003dh/GRB030329 late-time optical spectroscopy
  49. GRB040106, Radio Observations
  50. GRB040106, likely optical afterglow
  51. GRB040106: Second Epoch Optical Observations
  52. GRB 031220: Optical observations of Chandra X-ray sources
  53. GRB040106: optical observations with REM+ROSS
  54. GRB 040106: Optical observations
  55. GRB031220(=H2976): Observation with the Chandra X-ray Observatory
  56. GRB031220: Palomar Observations
  57. GRB 031203 I-band monitoring
  58. GRB 2974 follow-up observations
  59. GRB031203, improved XMM position
  60. GRB 031203: Discovery of a dust echo
  61. GRB 031203: SMARTS optical monitoring
  62. GRB 021203: A Normal GRB viewed far off axis?
  63. XMM-Newton Observations of GRB031203: Preliminary Images
  64. GRB 031203: Variable Radio Source
  65. GRB 031203: Magellan spectrum of possible GRB host
  66. GRB 031203: Optical/IR Astrometry
  67. GRB031203 K prime photometry: correction to galaxy coordinates
  68. GRB 031203: Deep NIR NTT & VLT observations
  69. GRB031203: K' Photometry of the likely GRB host
  70. GRB 031203: Radio detection
  71. GRB 031203: Further reports on December 4 observations
  72. GRB 031203: IR NTTobservations do not confirm REM detection
  73. GRB 031203: z ~ 10 or Fragmented Dust in the Circumburst Environment?
  74. GRB 031203: Apparent Spectral Break
  75. GRB 031203: IR REM Observations
  76. GRB031203: Optical Observations
  77. GRB 031203: Optical/IR SMARTS Observations
  78. GRB031111A, prompt optical observations
  79. GRB 031111, Radio observations
  80. GRB 031111: Optical observations
  81. GRB 031111, optical observations
  82. SN 2003jd (SN/GRB?) -- X-ray Observations
  83. GRB031026: 1.2mm upper limit with MAMBO at the IRAM 30m
  84. Lulin optical follow-up observations of GRB031026
  85. SN 2003jd (SN/GRB?), Radio Observations
  86. GRB 031026: Further Ic Observations
  87. GRB 031026 (=H2882): Evidence for High Redshift from Prompt
  88. Peculiar Type Ic SN 2003jd (SN/GRB?), optical spectrum
  89. GRB 031026: Ic Observations
  90. GRB030329: radio observations at RT-22 (CrAO)
  91. XRF 030824: additional observations at CFHT
  92. SGR 1806-20 bursts with INTEGRAL and IBAS announcement on Soft Gamma-Ray Repeaters
  93. XRF 030723: Subaru Optical Observations
  94. XRF 030824: observations at CFHT
  95. XRF 030723: Detection of the likely host galaxy
  96. GRB030913: Subaru Optical Observations
  97. GRB 030913: ROTSE-3c Optical Observations
  98. GRB030913, candidate afterglow observations
  99. GRB 030913, optical candidate
  100. GRB030913: AAVSO optical observations

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