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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"
  1. GRB 090509: GROND further analysis and redshift limit
  2. GRB 090509: REM NIR afterglow
  3. GRB 090509: GROND afterglow candidate
  4. GRB 090509: Swift detection of a burst
  5. GRB 090323: optical observations
  6. GRB 090423: optical limit
  7. GRB 090423: 250 GHz upper limit for a z=8.2 GRB with MAMBO-2 at the IRAM 30m
  8. GRB 080913: 250 GHz upper limit for a z=6.7 GRB with MAMBO-2 at the IRAM 30m
  9. GRB 090424: optical observations
  10. GRB 090427: GROND observations
  11. GRB 090429A: ROVOR magnitude limit
  12. ICSP VLF observation of GRB090427 from two receivers
  13. ICSP VLF observation of GRB090424 from four receivers
  14. Refined analysis of ICSP VLF observation of SGR J1550-5418 bursts on 22nd January, 2009
  15. GRB 090428B: Suzaku WAM observation of the prompt emission
  16. GRB 090424, SMARTS optical/IR afterglow monitoring
  17. GRB 090426: optical observations
  18. GRB 090429D: Fermi GBM detection
  19. GRB 090429C: Fermi GBM detection
  20. GRB 090429B: Swift/UVOT Upper Limits
  21. GRB 090429A: Swift/UVOT Upper Limits
  22. GRB 090427: pseudo-z= 1.48 from prompt emission spectrum
  23. GRB 090429B: Gemini-N further nIR observations
  24. GRB 090424: YNAO-GMG observations
  25. GRB 090429A: Swift-XRT refined analysis
  26. GRB 090429A: GROND upper limits
  27. GRB 090427C: Fermi GBM detection
  28. GRB 090427B: Fermi GBM detection
  29. GRB 090426C: Fermi GBM detection
  30. GRB 090426B: Fermi GBM detection/observation
  31. GRB 090429B: Swift XRT refined analysis
  32. GRB 090429A: Enhanced Swift-XRT position
  33. Konus-Wind observation of very bright GRB 090427
  34. GRB 090428B: Fermi GBM detection
  35. GRB 090428: Fermi GBM detection
  36. GRB 090418A BVRcIc field calibration
  37. GRB 090426: GAO 150cm telescope Optical Observation
  38. GRB 090429B: RIMOTS optical upper limits
  39. GRB 090429B: Swift-BAT refined analysis
  40. GRB 090429A: Swift-BAT refined analysis
  41. GRB 090429B: Enhanced Swift-XRT position
  42. GRB 090429A - Correction to XRT position
  43. GRB090429B: Gemini-N infrared IR candidate
  44. GRB 090426: YNAO-GMG observations
  45. GRB 090429B: VLT upper limits
  46. GRB 090429B: GROND Observations
  47. GRB 090429B: Super-LOTIS early observations
  48. GRB 090429B: Swift detection of a burst
  49. GRB 090429: Swift detection of a burst
  50. GRB 090423: pseudo burst at z=1 and its relation to GRB 080913
  51. GRB 090424 : Multiband Optical observation from Nainital
  52. IPN triangulation of very bright GRB 090427
  53. GRB 090426: R-band limit
  54. GRB 090424: Continued R-band monitoring
  55. GRB 090423: CARMA mm observations
  56. GRB 090423: millimeter detection
  57. GRB 090426: Swift/BAT spectral lag results
  58. GRB 090425: Fermi GBM detection
  59. GRB 090424: Suzaku WAM observation of the prompt emission
  60. GRB 090426: VLT spectroscopy
  61. GRB 090426: GROND Observations of the Optical/NIR Afterglow
  62. GRB 090426: Near infrared observation with ISLE at OAO
  63. GRB 090426: Okayama MITSuME optical observation
  64. GRB090426 Swift/UVOT observations
  65. GRB 090426 Keck LRIS redshift
  66. GRB 090426: Swift-BAT refined analysis
  67. GRB 090426: Swift-XRT refined analysis
  68. GRB 090423: GROND second epoch imaging and refined SED
  69. Detection of bright radio afterglow of GRB 090424 with the VLA
  70. GRB 090426: Enhanced Swift-XRT position
  71. GRB090426: Observation for Optical counterpart from MIRO
  72. GRB 090426, RIMOTS optical upper limits
  73. GRB 090426: inspection of SDSS images
  74. GRB 090426: TNT confimation of optical counterpart
  75. GRB 090426: Swift detection of a burst with an optical counterpart
  76. GRB090424: R-band detection (37.5 hrs post-burst), jet break?
  77. GRB 090424: MASTER-Net prompt optical limit
  78. GRB 090423: Fermi GBM observation (correction of isotropic equivalent energy)
  79. GRB 090424: WHT ISIS spectroscopy
  80. VLA radio observation of high-z GRB 090423
  81. GRB090424: BVRI/R-band detection after 15 hrs burst
  82. GRB 090424 : Lulin 1m telescope optical observations
  83. GRB 090424: THO optical observations
  84. GRB 090424: GROND Observations of the Optical/NIR Afterglow
  85. GRB090423: Y-band limit
  86. GRB 090424 Gemini-South Redshift
  87. GRB 090423: Y-band field calibration update/correction
  88. GRB 090423: Swift/BAT spectral lag results
  89. GRB 090424 : TAOS optical detection
  90. GRB 090424 optical observations
  91. GRB 090424: Liverpool Telescope observations
  92. GRB 090424: Swift-XRT refined analysis
  93. GRB 090424: Optical observations from 1.23m CAHA
  94. GRB 090423: energetic, luminosity and jet break
  95. Swift/UVOT observations of GRB 090424
  96. GRB 090424: MASTER-Net prompt optical observations
  97. GRB 090424: Enhanced Swift-XRT position
  98. GRB 090424: Swift-BAT refined analysis
  99. GRB 090424: Fermi GBM Observation
  100. GRB 090423: Fermi GBM observation

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