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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"

40643 results found.

  1. possible optical counterpart of GRB 000630
  2. GRB 000623, optical observations
  3. GRB 000620, optical observations
  4. GRB000418, HST/STIS Observations
  5. GRB990123: Late-time HST/STIS observations of the host
  6. GRB 990506, HST/STIS Observations of the Host Galaxy
  7. GRB 000620: J-band observations
  8. GRB000620, optical observations
  9. GRB000615: H-band observations
  10. GRB990308, HST/STIS observations of the host galaxy
  11. GRB000620 - Optical observations
  12. GRB000620 Optical observations
  13. IPN annulus for GRB000620
  14. GRB000620: BeppoSAX WFC and GRBM detection
  15. GRB000615, Radio observations
  16. GRB000607, optical observations
  17. GRB 000615: NIR further observations
  18. GRB990123, HST/STIS observations of the host galaxy
  19. GRB000616 optical observations
  20. GRB 000615, near-infrared observations
  21. GRB 990123: Late-time HST/STIS 50CCD observations of the host
  22. GRB000615, further R-band photometry
  23. GRB 000615: NIR observations
  24. GRB000615: BeppoSAX NFI follow-up preliminary analysis
  25. GRB000615, R-band photometry
  26. GRB980425, HST/STIS observations of the host galaxy
  27. GRB000615: BeppoSAX GRB Alert
  28. The Hosts of GRB 980703 and GRB 971214
  29. GRB 000301C: Further Late-Time HST/STIS observations
  30. GRB000528: follow-up X-ray measurements and update of IPN annulus
  31. Optical Follow-up of GRB000529 Error Box
  32. GRB980519, HST/STIS observations of the host galaxy
  33. GRB000607, Radio Observations
  34. BeppoSAX X-ray transient/possible GRB000608
  35. GRB000604 optical non-detection
  36. GRB000604 - Optical observations
  37. GRB000604, optical observations
  38. GRB000528, optical observations at ESO
  39. GRB 000604 optical observations
  40. GRB 000418: Detection of the Host Galaxy
  41. GRB000604, optical observations, comparison with DPOSS
  42. GRB000528, Radio Observations
  43. X-ray Afterglow of GRB 000529
  44. GRB000529: BeppoSAX NFI follow-up preliminary analysis
  45. GRB000528: BeppoSAX NFI follow-up preliminary analysis
  46. GRB000529: Optical Observations
  47. IPN localization and time history of GRB000528
  48. GRB000519: Optical observations
  49. IPN localization of GRB000529
  50. GRB 000528 - WFC measurements
  51. GRB000529: BeppoSAX WFC position
  52. GRB000528: BeppoSAX GRBM observations
  53. GRB 000528 Optical Observations
  54. GRB000519, BVRI field photometry
  55. Re: GRB000508B : Optical observations
  56. GRB 000418, Optical observation
  57. GRB000508B, optical photometry
  58. GRB000508B, BVR field photometry
  59. Possible GRB-related phenomenon
  60. RXTE/ASM and IPN localization of GRB 000508B
  61. GRB000424, UBVRI field photometry
  62. GRB 000424 Optical Observations
  63. GRB000418, UBVRI field photometry update
  64. The redshift of GRB 000418
  65. GRB000424, optical observations
  66. GRB 000429, optical observation
  67. GRB 000429, UBVRI field photometry
  68. IPN localization of GRB000429
  69. GRB 000418, UBVRI field photometry
  70. GRB000418, Radio detection
  71. GRB000418, K'-band photometry
  72. GRB 000418, Optical Observation
  73. GRB 000418, optical observation
  74. GRB000424 Optical Observations
  75. GRB 000418, Optical Observation
  76. GRB000424, optical observations
  77. GRB000424, optical observations
  78. GRB 000424, Optical Observations
  79. GRB 000418, Optical Observation
  80. GRB000418, near-infrared observations
  81. BeppoSAX GRB000424
  82. Correction to IPN error box for GRB000419
  83. GRB000416 Optical Observations
  84. BATSE observations of FXT/GRB 000416 = 1SAXJ1715.0-7134
  85. GRB000416 BRJK observations
  86. 1SAXJ1715.0-7134 refined position
  87. RE: Budget cuts in BeppoSAX operations: impact on GRB observation
  88. X-ray burst or X-ray rich GRB 000416 observed by BeppoSAX
  89. Budget cuts in BeppoSAX operations: impact on GRB observations
  90. GRB 000408, optical observations
  91. GRB 991208, UBVRI field photometry
  92. GRB000301c results
  93. GRB000408: Optical CCD Observations from MIRO
  94. GRB000408, lotis optical observations
  95. GRB 000301C: Late-Time HST/STIS CCD Imaging of the field
  96. GRB000408 [IPN Position]
  97. GRB000326 Optical Observations
  98. GRB000301C - R magnitude lower limit
  99. GRB000326, Further VLA observations
  100. GRB 000323, optical observations

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