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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"

20361 results found.

  1. GRB 030217: Optical Observations at 4, 5, and 6 Days
  2. IPN triangulation of GRB030217 (small error box)
  3. GRB030115, WSRT radio observations - correction to GCN 1864
  4. GRB 030131: marginal optical detection
  5. GRB030115, WSRT radio observations
  6. GRB 030204: Optical Observations
  7. GRB030204 field photometry
  8. GRB020819: Kiso R and I band observations
  9. GRB030131: Candidate Optical Afterglow
  10. IPN triangulation of GRB030204 (small error box)
  11. GRB 030131, optical observations
  12. GRB 030131: afterglow candidate
  13. GRB 030115, late-time optical observations
  14. Type Ic SN2003L (SN/GRB?), optical spectrum
  15. GRB 020819: Host galaxy at Radio Position
  16. GRB 030131 optical observations
  17. GRB 030131 optical observations
  18. A long GRB detected by INTEGRAL
  19. GRB 030115: Further IR observations with IRSF/SIRIUS
  20. GRB 030115, simultaneous observations by BOOTES-1
  21. GRB 030115: IR observations with IRSF/SIRIUS
  22. IPN triangulation of GRB030115C (large error box)
  23. GRB030115, afterglow candidate
  24. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  25. GRB 030115 : Possible IR counterpart
  26. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  27. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  28. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  29. GRB 030115: APO Optical Observations
  30. GRB on 20030102 seen by SPI-ACS
  31. VLT spectroscopy of the probable host of GRB 021211
  32. GRB 021211: Probable Host and Underlying Supernova
  33. GRB 021112: Evidence for Another Dark Optical Afterglow
  34. GRB 021219: OSN optical observations
  35. GRB021219: Radio Observations
  36. GRB021219, optical observations
  37. GRB021219, optical observation by MASTER
  38. GRB021219 refined position with INTEGRAL
  39. GRB021219: a long GRB localized by INTEGRAL
  40. GRB021211: APO optical observations
  41. XRF 020903 : HST observations
  42. GRB 021201: Optical Observations
  43. GRB 021211: CTIO observations
  44. VLT spectrum of GRB 021211
  45. GRB021211, BVRI field photometry
  46. GRB021211: Optical observations in CrAO
  47. GRB 021211, IR observations
  48. GRB 021211, optical observations
  49. GRB021211: Kiso Observations
  50. GRB 021201, optical observations
  51. GRB021211: Optical observations
  52. GRB 021201 (short/hard), NOT observations
  53. Chandra observation of the IPN error box of GRB021201 (short/hard)
  54. GRB 021211, R- and I-band observations
  55. GRB 021204: Optical Observations at RIKEN
  56. IPN triangulation of GRB021206 (small error box)
  57. IPN triangulation of GRB021205 (large error box)
  58. GRB021201, BVRcIc field photometry
  59. GRB 021201: BOOTES simultaneous optical observations
  60. IPN triangulation of GRB021201 (short/hard burst, small error box)
  61. GRB021004, late time optical observations
  62. IPN detection of continued SGR1900+14 activity
  63. Improved IPN error box for GRB021125
  64. IPN BURST POSITION
  65. IPN triangulation of GRB021125 (INTEGRAL BURST)
  66. GRB021125 : A long GRB localized by INTEGRAL
  67. IPN confirmation of the reactivation of SGR1900+14
  68. GRB021113, SPI ACS observation
  69. GRB 021112: Afterglow or Variable Star?
  70. GRB021113: optical observations at Bisei
  71. GRB021112, BVRI field photometry
  72. GRB 021112: Variable Source in R-band search
  73. GRB021112: Optical Observations
  74. GRB 021113: Optical observations
  75. GRB 021112: RAPTOR Observations
  76. GRB 021113: Optical Observations
  77. GRB021113 (=H2449): A Long GRB Localized by HETE
  78. GRB021112 (=H2448): A Long GRB Localized by HETE
  79. GRB 021016: Optical Observations
  80. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  81. SGR1900+14 activity, November 2-4, 2002
  82. GRB021104: optical observations
  83. Detection of activity from SGR 1900+14 with the RXTE/PCA
  84. IPN triangulation of GRB021027 (single large error box)
  85. GRB 021004: optical observations
  86. IPN triangulation of GRB021023 (small error boc)
  87. IPN triangulation of GRB021020 (smaller error box)
  88. IPN triangulation of GRB021020
  89. IPN triangulation of GRB021016 (small error box)
  90. IPN triangulation of GRB021014 (large error box)
  91. IPN triangulation of GRB021013 (single error box)
  92. IPN triangulation of GRB021013 (two small error boxes)
  93. GRB021004: High-resolution optical spectroscopy
  94. XRF 020903: flattening of the optical light curve.
  95. GRB021004, UBVRcIc field photometry update
  96. IPN triangulation of GRB021008 (single error box)
  97. IPN triangulation of GRB021008 (two small error boxes)
  98. GRB021004 Chandra HETG Observations
  99. GRB 021004: Optical/NIR Observations
  100. GRB 021004: Additional V-band Polarimetric Observations

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