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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"

41600 results found.

  1. GRB021206 optical counterpart upper limit
  2. XRF030723: Re-analysis of ROTSE-III early images
  3. IPN triangulation of GRB030725 (=H2779; small error box)
  4. XRF030723 (=H2777): Second Epoch Magellan Observations
  5. GRB 030725: optical observations.
  6. GRB030725, optical transient observations
  7. XRF030723 Radio Observations
  8. XRF 030723: confirmation of fading optical counterpart
  9. XRF030723(=H2777): Chandra Observations
  10. XRF 030723: VLT spectra
  11. Magellan Observations of XRF030723 (=H2777)
  12. GRB030723: Upper limits from historical observations
  13. GRB030725, possible optical transient
  14. XRF030723: Palomar observations and proposed counterpart
  15. XRF030723: optical observations
  16. XRF030723 (= H2777): Chandra Observations Scheduled
  17. XRF030723, ROTSE-III Early Observations
  18. XRF030723, BVRcIc field photometry
  19. XRF 030723, optical observations
  20. XRF030723, optical observations
  21. XRF 030723, optical observations
  22. XRF030723 (=H2777): An X-ray Flash Localized by the HETE WXM and
  23. GRB030723, optical observations
  24. Konus-Wind detection of the bursts from SGR1806-20 region
  25. SGR 1806-20, submm observations
  26. H2768, H2770, and H2771: Three Bursts from SGR1806-20
  27. RXTE PCA Observations of SGR1806-20 Region
  28. GRB030329: Subaru Optical Spectroscopy
  29. Triangulation of GRB030715 (single large error box)
  30. Triangulation of GRB030714 (single large error box)
  31. IPN triangulation of GRB030714 (two large error boxes)
  32. IPN triangulation of GRB030715 (two large error boxes)
  33. GRB030329: RTT150 optical observations
  34. GRBlog: Compilation of all GCN Circ. data
  35. IPN detection of renewed activity from SGR1806-20
  36. GRB030329, optical observation in May
  37. IPN triangulation of GRB030626 (two large error boxes)
  38. GRB030329: second XMM-Newton observation
  39. GRB030418: R optical observations
  40. GRB030329 -- RATAN-600 data in April-May
  41. Final IPN error ellipse for GRB021206 (the polarized GRB)
  42. GRB 021206, Radio afterglow candidate
  43. GRB030528(=H2724): X-ray Afterglow Identified in Second Epoch
  44. IPN triangulation of GRB030607 (annulus)
  45. IPN triangulation of GRB030606 (two alternate error boxes)
  46. GRB030329, SPM optical observations (Correction of GCN2075 R band)
  47. GRB 030528: Infrared Observations and the Proposed IR Counterpart
  48. GRB 030528: Optical Observations
  49. GRB 030528: tentative NIR counterpart
  50. GRB 030528, radio observations
  51. GRB030528(=H2724): Observations with the Chandra X-ray Observatory
  52. GRB030329, further radio observations at GMRT
  53. GRB030528, BVRI field photometry
  54. GRB030329, SPM optical observations
  55. GRB030528: Chandra TOO Planned
  56. GRB 030519B: optical observations.
  57. MASTER: optical observation GRB030601
  58. GRB030528(=H2724): Revised SXC Localization
  59. GRB 030329: optical observations
  60. GRB 030329/SN 2003dh: Jitter Episode
  61. GRB 030528, Teramo optical observation
  62. GRB 030528 Bisei optical observation
  63. GRB 030329: Correction to GCN 2254
  64. GRB 030329: Optical Observations
  65. GRB 030528: Optical observations at RIKEN
  66. GRB 030528 (=H2724) Kyoto optical observation
  67. GRB 030416: Optical Observations
  68. GRB 030329: optical photometry at Belesta observatory (France)
  69. GRB030329, Optical observations
  70. GRB 030329/SN 2003dh: Possible increase in brightness
  71. GRB 030329: HST ACS Observations of the Host
  72. GRB 030329 Optical Observations
  73. GRB030329: XMM-Newton observation
  74. GRB 021004: HST observations
  75. GRB030324: Further Observations of the Candidate Optical Afterglow
  76. GRB030519B (=H2716): Peak Fluxes, Fluences, and Energy Spectrum
  77. GRB 030418: Second Epoch Optical Observations with Magellan
  78. IPN triangulation of GRB030518B (annulus)
  79. HETE GRB030329, correction to Rc Observations in Loiano
  80. GRB 030329: Optical limit (contemporaneous imaging)
  81. IPN triangulation of GRB030509 (small errror box)
  82. GRB030329: RTT150 optical observations
  83. GRB030329, BVRI photometry
  84. GRB030429, refiend optical brightness
  85. GRB 030329: Optical limit (contemporaneous photography)
  86. GRB030418, BVRcIc field photometry
  87. GRB 030429: Redshift of neighbor galaxy
  88. GRB030429, BVRcIc field photometry
  89. GRB 030329: High-Resolution Spectroscopy of the Host
  90. GRB030429: RTT150 optical observations, a possible host galaxy
  91. GRB030329: RTT150 optical observations and upper limit for a host
  92. GRB 030329: all-sky CCD images by K. Shiokawa immediately after the burst
  93. GRB030501, optical observation
  94. GRB030501 observation report
  95. GRB030329: RTT150 optical observations and upper limit for a host
  96. GRB 030429: Radio Observations
  97. GRB 030429: redshift from VLT spectroscopy
  98. GRB 030429: IR photometry with IRSF/SIRIUS
  99. GRB 030329 Optical Observations
  100. GRB030328, optical observation

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