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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. GRB021206 optical counterpart upper limit
  2. IPN triangulation of GRB030731 (annulus)
  3. IBAS GRB Alerts 1011-1017 NOT CONFIRMED
  4. XRF030723: Re-analysis of ROTSE-III early images
  5. IPN triangulation of GRB030725 (=H2779; small error box)
  6. XRF030723 (=H2777): Second Epoch Magellan Observations
  7. GRB 030725: optical observations.
  8. GRB030725, optical transient observations
  9. IPN triangulation of GRB030726 (large error box)
  10. IPN triangulation of GRB030722 (large error box)
  11. IPN triangulation of GRB030721 (large error box)
  12. XRF030723 Radio Observations
  13. XRF 030723: confirmation of fading optical counterpart
  14. XRF030723(=H2777): Chandra Observations
  15. XRF 030723: VLT spectra
  16. Magellan Observations of XRF030723 (=H2777)
  17. GRB030723: Upper limits from historical observations
  18. GRB030725, possible optical transient
  19. XRF030723: Palomar observations and proposed counterpart
  20. GRB030725 (=H2779): A Bright GRB Localized by HETE
  21. XRF030723: optical observations
  22. XRF030723 (= H2777): Chandra Observations Scheduled
  23. XRF030723, BVRcIc field photometry correction
  24. XRF030723, ROTSE-III Early Observations
  25. XRF030723, BVRcIc field photometry
  26. XRF 030723, optical observations
  27. XRF030723, optical observations
  28. XRF 030723, optical observations
  29. XRF030723 (=H2777): An X-ray Flash Localized by the HETE WXM and
  30. GRB030723, optical observations
  31. Konus-Wind detection of the bursts from SGR1806-20 region
  32. IBAS GRB Alerts 969 970
  33. SGR 1806-20, submm observations
  34. H2768, H2770, and H2771: Three Bursts from SGR1806-20
  35. IPN triangulation of GRB030717 (annulus)
  36. RXTE PCA Observations of SGR1806-20 Region
  37. GRB030329: Subaru Optical Spectroscopy
  38. Triangulation of GRB030715 (single large error box)
  39. Triangulation of GRB030714 (single large error box)
  40. 030716 NOT a GRB
  41. IPN triangulation of GRB030714 (two large error boxes)
  42. IPN triangulation of GRB030715 (two large error boxes)
  43. GRB030329: RTT150 optical observations
  44. GRBlog: Compilation of all GCN Circ. data
  45. IPN detection of renewed activity from SGR1806-20
  46. IPN triangulation of GRB030711 (annulus, =SGR0525-66?)
  47. IPN triangulation of GRB030710 (annulus)
  48. IPN triangulation of GRB030709 (annulus)
  49. GRB030706 triangulation (single large error box)
  50. IPN triangulation of GRB030706 (annulus)
  51. IPN triangulation of GRB030629 (annulus)
  52. GRB030629 triangulation (Konus-Wind -- Helicon annulus)
  53. 030629 NOT a real GRB
  54. GRB030329, optical observation in May
  55. IPN triangulation of GRB030626 (single large error box)
  56. IPN triangulation of GRB030626 (two large error boxes)
  57. GRB030329: second XMM-Newton observation
  58. GRB030418: R optical observations
  59. HETE detection of burst from SGR1806-20
  60. GRB030329 -- RATAN-600 data in April-May
  61. Final IPN error ellipse for GRB021206 (the polarized GRB)
  62. GRB 021206, Radio afterglow candidate
  63. GRB030528(=H2724): X-ray Afterglow Identified in Second Epoch
  64. IPN triangulation of GRB030607 (annulus)
  65. IPN triangulation of GRB030606 (two alternate error boxes)
  66. GRB030329, SPM optical observations (Correction of GCN2075 R band)
  67. GRB 030528: Infrared Observations and the Proposed IR Counterpart
  68. IPN triangulation of GRB030605B (annulus)
  69. GRB 030528: Optical Observations
  70. IPN triangulation of GRB030605 (annulus)
  71. GRB 030528: tentative NIR counterpart
  72. GRB 030528, radio observations
  73. GRB030528(=H2724): Observations with the Chandra X-ray Observatory
  74. GRB030329, further radio observations at GMRT
  75. GRB030528, BVRI field photometry
  76. IPN triangulation of GRB030601 (annulus)
  77. GRB030329, SPM optical observations
  78. GRB030528: Chandra TOO Planned
  79. GRB 030519B: optical observations.
  80. MASTER: optical observation GRB030601
  81. GRB030528(=H2724): Revised SXC Localization
  82. GRB 030329: optical observations
  83. GRB 030329/SN 2003dh: Jitter Episode
  84. GRB 030528, Teramo optical observation
  85. GRB 030528 Bisei optical observation
  86. GRB030528 (H2724): A long GRB localized by HETE
  87. GRB 030329: Correction to GCN 2254
  88. GRB 030329: Optical Observations
  89. GRB 030528: Optical observations at RIKEN
  90. GRB 030528 (=H2724) Kyoto optical observation
  91. IPN triangulation of GRB030523B (annulus)
  92. GRB 030416: Optical Observations
  93. GRB 030329: Planned XMM-Newton Observation
  94. IPN triangulation of GRB030523 (annulus)
  95. GRB 030329: optical photometry at various french observatories
  96. GRB 030329: optical photometry at Belesta observatory (France)
  97. GRB030329, Optical observations
  98. GRB 030329/SN 2003dh: Possible increase in brightness
  99. GRB 030329: HST ACS Observations of the Host
  100. GRB 030329 Optical Observations

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