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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"

21769 results found.

  1. GRB 030328: optical observations
  2. GRB 030329: Optical afterglow fading
  3. GRB 030329: Optical afterglow candidate
  4. GRB 030328: OT photometry
  5. GRB030328: optical photometry at the TNG
  6. GRB030328 (=H2650): A Long, Bright GRB Localized by the HETE WXM and SXC
  7. GRB 030328: Optical observations
  8. GRB030324 optical observation
  9. GRB030131, BVRcIc field photometry
  10. Possible GRB030323 localized by INTEGRAL
  11. GRB030323: Detection on 2003/03/24
  12. GRB030324, optical observations
  13. GRB030323: V, R, I photometry
  14. GRB030323 (=H2640): A Faint, Long GRB Localized by the HETE WXM and SXC
  15. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  16. VLT/FORS2 spectra of GRB 030323
  17. GRB030323, ROTSE-III detection of possible optical counterpart
  18. GRB030323, optical observations
  19. GRB030324, BVRcIc field photometry
  20. GRB030323, BVRcIc field calibration
  21. Possible GRB 030320 localized by INTEGRAL
  22. GRB030226, BVRc observations
  23. Chandra detection of the X-ray afterglow of GRB 030226
  24. GRB 030226: Ic Observations
  25. GRB030227: Kiso optical upper limit
  26. GRB030227, BVRcIc field photometry
  27. GRB030226, BVRcIc field calibration
  28. GRB 030228, optical observations
  29. GRB 030227: Confirmed Optical Afterglow (S1-A)
  30. GRB 030227: fading of candidate optical afterglow 'S1-A'
  31. GRB030227:Optical observations
  32. GRB 030227, possible optical counterpart of XMM-Newton source
  33. GRB030227: Kiso optical observations
  34. GRB 030227: Kyoto optical observation
  35. GRB030227 localized by INTEGRAL
  36. Possible break in the GRB 030226 light curve
  37. GRB030226: ESI spectroscopy
  38. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  39. GRB 030226 simultaneous optical observations
  40. GRB 030226, optical observations
  41. GRB030226: Optical decay index
  42. GRB 030217: Optical Observations at 4, 5, and 6 Days
  43. GRB 030131: marginal optical detection
  44. GRB 030204: Optical Observations
  45. GRB030204 field photometry
  46. GRB020819: Kiso R and I band observations
  47. GRB030131: Candidate Optical Afterglow
  48. GRB 030131, optical observations
  49. GRB 030131: afterglow candidate
  50. GRB 030115, late-time optical observations
  51. GRB030131: corrected INTEGRAL position
  52. GRB 020819: Host galaxy at Radio Position
  53. IPN triangulation of GRB030131
  54. GRB 030131 optical observations
  55. GRB030131: refined position
  56. GRB 030131 optical observations
  57. A long GRB detected by INTEGRAL
  58. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  59. GRB 030115, simultaneous observations by BOOTES-1
  60. GRB 030115: IR observations with IRSF/SIRIUS
  61. GRB030115, afterglow candidate
  62. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  63. GRB 030115 : Possible IR counterpart
  64. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  65. GRB 030115: APO Optical Observations
  66. IPN triangulation of GRB030102 (annulus)
  67. VLT spectroscopy of the probable host of GRB 021211
  68. GRB 021211: Probable Host and Underlying Supernova
  69. GRB 021112: Evidence for Another Dark Optical Afterglow
  70. GRB 021219: OSN optical observations
  71. GRB021219, optical observations
  72. GRB021219, optical observation by MASTER
  73. GRB021219: a long GRB localized by INTEGRAL
  74. GRB021211: APO optical observations
  75. IPN detection of continued activity from SGR1806-20
  76. XRF 020903 : HST observations
  77. GRB 021201: Optical Observations
  78. GRB 021211: CTIO observations
  79. GRB 021211: early break in light curve
  80. GRB021211, BVRI field photometry
  81. GRB021211: Optical observations in CrAO
  82. GRB 021211, optical observations
  83. GRB021211: Kiso Observations
  84. GRB 021201, optical observations
  85. GRB021211: Optical observations
  86. GRB 021201 (short/hard), NOT observations
  87. Chandra observation of the IPN error box of GRB021201 (short/hard)
  88. GRB 021211, R- and I-band observations
  89. GRB021211 - Upper limits from recent and historical observations
  90. GRB 021204: I-band Observations
  91. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  92. GRB 021125: Radio Observations
  93. IPN detection of renewed activity from SGR1806-20
  94. GRB 021104, GRB 021112 and GRB 021113 - Milagro GeV/TeV Observations
  95. GRB021201, BVRcIc field photometry
  96. GRB 021201: BOOTES simultaneous optical observations
  97. GRB021004, late time optical observations
  98. GRB021125 : A long GRB localized by INTEGRAL
  99. GRB 021112: Afterglow or Variable Star?
  100. GRB021113: optical observations at Bisei

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