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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. IPN triangulation of GRB030505A (annulus)
  2. GRB030329: RTT150 optical observations and upper limit for a host
  3. GRB 030329: all-sky CCD images by K. Shiokawa immediately after the burst
  4. GRB030501, optical observation
  5. GRB030501 observation report
  6. GRB030501C triangulation (annulus)
  7. GRB030501 triangulation (correction to GCN 2194)
  8. GRB030329: RTT150 optical observations and upper limit for a host
  9. GRB 030429: Radio Observations
  10. GRB 030429: redshift from VLT spectroscopy
  11. GRB 030429: IR photometry with IRSF/SIRIUS
  12. GRB030501B triangulation (single error box)
  13. GRB 030329 Optical Observations
  14. GRB030328, optical observation
  15. GRB 030329, BVRI photometry
  16. GRB030429: Optical Observations
  17. GRB030501: TAROT candidate afterglow present in archival images
  18. GRB 030501: TAROT possible candidate counterpart
  19. IPN triangulation of GRB030501 (IBIS event; annulus)
  20. IPN triangulation of GRB030501B (annulus)
  21. GRB 030429: confirmation of afterglow candidate
  22. GRB030429, possible optical counterpart
  23. GRB030501 localized by INTEGRAL
  24. GRB030425: CrAO optical observation
  25. IPN triangulation of GRB030429 (annulus)
  26. IPN triangulation of GRB030428 (two large error boxes)
  27. GRB 030329 Oprical observations in Rozhen observatory
  28. GRB 030429: ROTSE-III observations
  29. GRB 030324: Radio Observations
  30. GRB030329 observed as a sudden ionospheric disturbance (SID)
  31. IPN triangulation of GRB030426 (annulus)
  32. SNeIa AS THE POSSIBLE PROGENITORS OF SHORT-DURATION GRBs.
  33. IPN triangulation of GRB030425 (single error box)
  34. GRB030329, SPM optical observations (Correction)
  35. GRB030329, SPM optical observations
  36. GRB 030329, the review of the sky area in plate archive (1950-1998)
  37. GRB 030329: Spectral Evolution of SN 2003dh
  38. Optical Observations of GRB 030418 with Magellan
  39. GRB 030329: optical spectropolarimetry at VLT
  40. IPN triangulation of GRB030422C (annulus)
  41. IPN triangulation of GRB030422B (annulus)
  42. GRB 030329: wide-field photograph by R. Tamura 1 hr after the burst
  43. GRB030329: optical polarization
  44. IPN triangulation of GRB030422 (two large error boxes)
  45. GRB 030329 3.5 and 6 cm radio observations at RTF-32 telescope
  46. GRB030329, optical observation
  47. IPN triangulation of GRB030421 (annulus)
  48. MASTER:optical observations GRB030418
  49. MASTER:optical observations probable GRB030414
  50. GRB030329: 444 AAVSO Measurements
  51. IPN triangulation of GRB030419 (annulus)
  52. MASTER:optical observations GRB030416
  53. ROTSE-III prompt optical detections of GRB 030418
  54. GRB030418: Upper limits from recent and historical observations.
  55. GRB030418: Kiso near infrared observations
  56. GRB 030418: Optical afterglow
  57. GRB 030418: Finder for afterglow candidate
  58. GRB 030418: Optical afterglow candidate
  59. GRB 030329 OT position
  60. GRB030329: Optical Observations
  61. OT GRB 030329: early UBVRcIc spectral evolution
  62. GRB030329, UBVRI polarimetry, R-polarization
  63. GRB 030329: SARA Optical Observations
  64. OT GRB 030329: early spectrum
  65. GRB030329: VR Photometry at TNG
  66. GRB030324: Candidate Optical Afterglow (Erratum)
  67. GRB030324: Candidate Optical Afterglow
  68. IPN triangulation of GRB030414 (small error box)
  69. GRB 030413: Optical Observations
  70. GRB 030329 Rc observations
  71. IPN triangulation of GRB030413 (small error box)
  72. IPN triangulation of GRB030410 (annulus)
  73. Superluminal motion in GRB 030329 (Correction)
  74. Superluminal motion in GRB 030329
  75. GRB 030329 and SN 2003dh
  76. GRB030329, optical position
  77. GRB 030329 VLBA Observations
  78. CORRECTION TO IPN TRIANGULATION OF GRB050403
  79. IPN triangulation of GRB030406 (small error box)
  80. IPN triangulation of GRB050403 (small error box)
  81. IPN triangulation of GRB030403 (annulus)
  82. GRB 030329: BVRI photometry at Asiago
  83. GRB 030329, light curve flattens
  84. GRB 030329: VLT V-band photometry
  85. If the SN/GRB connection confirmed
  86. GRB 030329: Supernova Confirmed
  87. GRB030329: RTT150 optical observations
  88. GRB030329: Near Infrared Observations at Gunma
  89. GRB030329: HET spectroscopic monitoring
  90. Kiso observation of the GRB030329 at April 6
  91. GRB 030329, color evolution
  92. GRB030328, UBVRcIc field photometry
  93. GRB030329: Optical observcations
  94. GRB030329: BV photographic observations
  95. GRB 030329 Optical observations
  96. GRB 030329, color evolution
  97. GRB 030329: possible color change
  98. GRB030329: RTT150 optical observations
  99. GRB 030329: Supernova Spectrum Emerging
  100. GRB030329: Kiso B and R band observations

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