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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"

28049 results found.

  1. GRB 030131: marginal optical detection
  2. GRB 030204: Optical Observations
  3. GRB030204 field photometry
  4. GRB020819: Kiso R and I band observations
  5. GRB030131: Candidate Optical Afterglow
  6. IPN triangulation of GRB030204 (small error box)
  7. GRB 030131, optical observations
  8. GRB 030131: afterglow candidate
  9. GRB 030115, late-time optical observations
  10. GRB030131: corrected INTEGRAL position
  11. GRB 020819: Host galaxy at Radio Position
  12. IPN triangulation of GRB030131
  13. GRB 030131 optical observations
  14. GRB 030131 optical observations
  15. A long GRB detected by INTEGRAL
  16. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  17. GRB 030115, simultaneous observations by BOOTES-1
  18. GRB 030115: IR observations with IRSF/SIRIUS
  19. IPN triangulation of GRB030115C (large error box)
  20. GRB030115, afterglow candidate
  21. GRB 021211: R-band observations at late-time
  22. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  23. GRB 030115 : Possible IR counterpart
  24. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  25. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  26. GRB 030115: APO Optical Observations
  27. Information about where HETE will be pointing
  28. VLT spectroscopy of the probable host of GRB 021211
  29. IPN triangulation of GRB030101 (two large error boxes)
  30. GRB 021211: Probable Host and Underlying Supernova
  31. GRB 021112: Evidence for Another Dark Optical Afterglow
  32. GRB 021219: OSN optical observations
  33. GRB021219, optical observations
  34. GRB021219, optical observation by MASTER
  35. VLT spectra of GRB 021211 revisited
  36. GRB021219: a long GRB localized by INTEGRAL
  37. GRB021211: APO optical observations
  38. XRF 020903 : HST observations
  39. GRB 021201: Optical Observations
  40. GRB 021211: CTIO observations
  41. GRB021211, BVRI field photometry
  42. GRB021211: Optical observations in CrAO
  43. GRB 021211, optical observations
  44. GRB021211: Kiso Observations
  45. GRB 021201, optical observations
  46. GRB021211: Optical observations
  47. GRB 021201 (short/hard), NOT observations
  48. SUB-MM SEARCH FOR GRB 021211
  49. Chandra observation of the IPN error box of GRB021201 (short/hard)
  50. GRB 021211, R- and I-band observations
  51. GRB021211 - Upper limits from recent and historical observations
  52. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  53. IPN triangulation of GRB021206 (small error box)
  54. IPN triangulation of GRB021205 (large error box)
  55. GRB021201, BVRcIc field photometry
  56. GRB 021201: BOOTES simultaneous optical observations
  57. IPN triangulation of GRB021201 (short/hard burst, small error box)
  58. GRB021004, late time optical observations
  59. GRB021004 Chandra Observation
  60. IPN detection of continued SGR1900+14 activity
  61. Improved IPN error box for GRB021125
  62. IPN BURST POSITION
  63. IPN triangulation of GRB021125 (INTEGRAL BURST)
  64. GRB021125 : A long GRB localized by INTEGRAL
  65. IPN confirmation of the reactivation of SGR1900+14
  66. GRB021113, SPI ACS observation
  67. GRB 021112: Afterglow or Variable Star?
  68. GRB021113: optical observations at Bisei
  69. GRB 021113: Evidence for a Dark Optical Afterglow
  70. GRB021112, BVRI field photometry
  71. GRB 021112: Variable Source in R-band search
  72. GRB021112: Optical Observations
  73. IPN triangulation of GRB021113 (=H2449; annulus)
  74. GRB 021113: Optical observations
  75. GRB 021112: RAPTOR Observations
  76. GRB021113 (=H2449): A Long GRB Localized by HETE
  77. GRB021112 (=H2448): A Long GRB Localized by HETE
  78. GRB 021016: Optical Observations
  79. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  80. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  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. IPN triangulation of GRB021027 (two large error boxes)
  86. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  87. GRB 021004: optical observations
  88. IPN triangulation of GRB021023 (small error boc)
  89. GRB 020813; likely host galaxy.
  90. IPN triangulation of GRB021020 (smaller error box)
  91. IPN triangulation of GRB021020
  92. GRB 021008, optical observations
  93. IPN triangulation of GRB021016 (small error box)
  94. IPN triangulation of GRB021014 (large error box)
  95. IPN triangulation of GRB021013 (single error box)
  96. GRB 021004: optical spectroscopy on Oct 11
  97. IPN triangulation of GRB021013 (two small error boxes)
  98. GRB021004: High-resolution optical spectroscopy
  99. XRF 020903: flattening of the optical light curve.
  100. GRB021004, UBVRcIc field photometry update

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