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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"

21801 results found.

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

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