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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"

28051 results found.

  1. GRB: Non-Referencing of GCN Circulars.
  2. IPN triangulation of GRB030217 (small error box)
  3. GRB 030131: marginal optical detection
  4. GRB 030204: Optical Observations
  5. GRB030204 field photometry
  6. GRB020819: Kiso R and I band observations
  7. GRB030131: Candidate Optical Afterglow
  8. IPN triangulation of GRB030204 (small error box)
  9. GRB 030131, optical observations
  10. GRB 030131: afterglow candidate
  11. GRB 030115, late-time optical observations
  12. GRB030131: corrected INTEGRAL position
  13. GRB 020819: Host galaxy at Radio Position
  14. IPN triangulation of GRB030131
  15. GRB 030131 optical observations
  16. GRB 030131 optical observations
  17. A long GRB detected by INTEGRAL
  18. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  19. GRB 030115, simultaneous observations by BOOTES-1
  20. GRB 030115: IR observations with IRSF/SIRIUS
  21. IPN triangulation of GRB030115C (large error box)
  22. GRB030115, afterglow candidate
  23. GRB 021211: R-band observations at late-time
  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. GRB 030115: APO Optical Observations
  29. Information about where HETE will be pointing
  30. VLT spectroscopy of the probable host of GRB 021211
  31. IPN triangulation of GRB030101 (two large error boxes)
  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, optical observations
  36. GRB021219, optical observation by MASTER
  37. VLT spectra of GRB 021211 revisited
  38. GRB021219: a long GRB localized by INTEGRAL
  39. GRB021211: APO optical observations
  40. XRF 020903 : HST observations
  41. GRB 021201: Optical Observations
  42. GRB 021211: CTIO observations
  43. GRB021211, BVRI field photometry
  44. GRB021211: Optical observations in CrAO
  45. GRB 021211, optical observations
  46. GRB021211: Kiso Observations
  47. GRB 021201, optical observations
  48. GRB021211: Optical observations
  49. GRB 021201 (short/hard), NOT observations
  50. SUB-MM SEARCH FOR GRB 021211
  51. Chandra observation of the IPN error box of GRB021201 (short/hard)
  52. GRB 021211, R- and I-band observations
  53. GRB021211 - Upper limits from recent and historical observations
  54. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  55. IPN triangulation of GRB021206 (small error box)
  56. IPN triangulation of GRB021205 (large error box)
  57. GRB021201, BVRcIc field photometry
  58. GRB 021201: BOOTES simultaneous optical observations
  59. IPN triangulation of GRB021201 (short/hard burst, small error box)
  60. GRB021004, late time optical observations
  61. GRB021004 Chandra Observation
  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. GRB 021113: Evidence for a Dark Optical Afterglow
  72. GRB021112, BVRI field photometry
  73. GRB 021112: Variable Source in R-band search
  74. GRB021112: Optical Observations
  75. IPN triangulation of GRB021113 (=H2449; annulus)
  76. GRB 021113: Optical observations
  77. GRB 021112: RAPTOR Observations
  78. GRB021113 (=H2449): A Long GRB Localized by HETE
  79. GRB021112 (=H2448): A Long GRB Localized by HETE
  80. GRB 021016: Optical Observations
  81. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  82. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  83. SGR1900+14 activity, November 2-4, 2002
  84. GRB021104: optical observations
  85. Detection of activity from SGR 1900+14 with the RXTE/PCA
  86. IPN triangulation of GRB021027 (single large error box)
  87. IPN triangulation of GRB021027 (two large error boxes)
  88. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  89. GRB 021004: optical observations
  90. IPN triangulation of GRB021023 (small error boc)
  91. GRB 020813; likely host galaxy.
  92. IPN triangulation of GRB021020 (smaller error box)
  93. IPN triangulation of GRB021020
  94. GRB 021008, optical observations
  95. IPN triangulation of GRB021016 (small error box)
  96. IPN triangulation of GRB021014 (large error box)
  97. IPN triangulation of GRB021013 (single error box)
  98. GRB 021004: optical spectroscopy on Oct 11
  99. IPN triangulation of GRB021013 (two small error boxes)
  100. GRB021004: High-resolution optical spectroscopy

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