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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"

44355 results found.

  1. GRB000424, UBVRI field photometry
  2. GRB 000424 Optical Observations
  3. GRB000418, UBVRI field photometry update
  4. The redshift of GRB 000418
  5. GRB000424, optical observations
  6. GRB 000429, optical observation
  7. GRB 000429, UBVRI field photometry
  8. IPN localization of GRB000429
  9. GRB 000418, UBVRI field photometry
  10. GRB000418, Radio detection
  11. GRB000418, K'-band photometry
  12. GRB 000418, Optical Observation
  13. GRB 000418, optical observation
  14. GRB000424 Optical Observations
  15. GRB 000418, Optical Observation
  16. GRB000424, optical observations
  17. GRB000424, optical observations
  18. GRB 000424, Optical Observations
  19. GRB 000418, Optical Observation
  20. GRB000418, near-infrared observations
  21. BeppoSAX GRB000424
  22. Correction to IPN error box for GRB000419
  23. IPN error box for GRB000418
  24. GRB000419 [IPN Position]
  25. GRB000416 Optical Observations
  26. BATSE observations of FXT/GRB 000416 = 1SAXJ1715.0-7134
  27. GRB000416 BRJK observations
  28. 1SAXJ1715.0-7134 refined position
  29. RE: Budget cuts in BeppoSAX operations: impact on GRB observation
  30. X-ray burst or X-ray rich GRB 000416 observed by BeppoSAX
  31. Budget cuts in BeppoSAX operations: impact on GRB observations
  32. GRB 000408, optical observations
  33. Refined IPN error box for GRB000408
  34. GRB 991208, UBVRI field photometry
  35. GRB000301c results
  36. GRB000408: Optical CCD Observations from MIRO
  37. GRB000408, lotis optical observations
  38. GRB 000301C: Late-Time HST/STIS CCD Imaging of the field
  39. GRB000408 [IPN Position]
  40. GRB000326 Optical Observations
  41. GRB000301C - Addendum to GCN 623
  42. GRB000301C - R magnitude lower limit
  43. GRB000326, Further VLA observations
  44. GRB 000323, optical observations
  45. GRB 000326: Optical Observations
  46. GRB000326, Radio observations
  47. GRB000326 [IPN Position]
  48. GRB 000307 optical observations
  49. GRB000323 [IPN Position]
  50. Single error box for GRB000315
  51. GRB000315 [IPN Positions]
  52. GRB000313, Radio observations
  53. GRB 000313 - optical transient in the BATSE error box
  54. GRB000301C - B and R photometry
  55. GRB000301C - R photometry
  56. GRB 000307, Optical Observations
  57. GRB 000307, BVRI Field Photometry
  58. GRB 000301C: Optical Spectrum and Redshift
  59. GRB 000301C: Optical Spectrum and Redshift
  60. GRB 000301C: A Precise Redshift Determination
  61. GRB 000301C, Optical Observation
  62. GRB 000301C: HST/STIS-PRISM NUV-MAMA spectroscopy
  63. GRB 000301C: HST/STIS CCD Imaging of the field
  64. IPN error box for GRB000307
  65. GRB 000301c: K' observations
  66. GRB000301C, optical R-band observations
  67. GRB000301c - R photometry and nearby faint source confirmation
  68. GRB 000301C, Optical Observation
  69. GRB 000301c: K' observations
  70. GRB 000301C Optical Observations
  71. GRB 000301C: K' Observations
  72. GRB000301C OT candidate optical observations
  73. GRB000301C - Host galaxy not detected in R (?)
  74. Optical observations of GRB000301c
  75. GRB000301C, Radio observations
  76. GRB000301C, Radio observations
  77. GRB000301C optical observations
  78. GRB000301C, near-infrared observations (JHK' imaging)
  79. GRB 000301c near-IR observations
  80. GRB 000301C, Optical Color
  81. GRB000301C, Optical Spectroscopy
  82. GRB 000301C, UBVRI field photometry
  83. GRB 000301C, Optical Observation
  84. GRB000301C, optical observations
  85. GRB000301C 250 GHz detection
  86. GRB 000301C R-band observation
  87. GRB 000301C, Optical Observation
  88. GRB000301C, near-infrared observations (JHK' photometry)
  89. GRB 000301C: OT confirmed
  90. GRB000301c optical observations
  91. GRB 000301A, Radio Observations
  92. GRB000301C, optical observations
  93. GRB000301c, near-infrared observations
  94. GRB000301C
  95. GRB 000301C : Optical Candidate
  96. Radio observations of the error box of GRB000301A
  97. GRB000301C: RXTE/ASM and IPN localizations
  98. GRB000226 [IPN Position]
  99. HST Observations of GRB 990712
  100. GRB 000214 near-IR observations

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