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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"

2623 results found.

  1. GRB 140311C: MASTER optical observations
  2. GRB 140311C: Swift-XRT and UVOT observations
  3. Fermi416242156: possible iPTF counterpart
  4. GRB 140226A/iPTF14yb: Mondy optical observations
  5. GRB 140219A: Mondy optical observations of XRT source #5
  6. Konus-Wind observation of GRB 140226A
  7. IPN triangulation of GRB 140226A, a possible GRB counterpart to iPTF14yb
  8. iPTF14yb: Swift-XRT detection
  9. GRB 140219A: Xuyi and Nanshan upper limits
  10. GRB 140209A, Swift-BAT refined analysis
  11. GRB 140209A: optical observations
  12. GRB 140206A: theoretical prediction of redshift and of supernova occurrence
  13. GRB 140110A: Second Follow-up Swift-XRT Observation
  14. GRB 140104B: Further Swift XRT observations
  15. GRB 140108A: theoretical prediction of redshift and of supernova occurrence
  16. GRB 140105A/Fermi410578384: MASTER-Net early optical observations
  17. Fermi410578384: iPTF optical afterglow candidates for a possible short GRB
  18. GRB 131202A: theoretical estimation of the redshift
  19. GRB 060614: theoretical derivation of the redshift and need for deeper search of the host galaxy
  20. GRB 131128A: Swift detection of a burst
  21. GRB 131122A: i-band observations from NOT
  22. IPN Triangulation of GRB 131118A
  23. GRB 130925A: HST imaging
  24. GRB 131108A: 1.23m CAHA optical candidate
  25. GRB 131108A: Swift detection of a possible X-ray afterglow
  26. GRB 131103A: Swift detection of a burst
  27. GRB 131024C: ICSP discovery of a burst in X-rays by balloon borne study
  28. IPN Triangulation of GRB 131028A (long/bright)
  29. Swift Trigger 575905/possible GRB 131026A: Swift-XRT observations
  30. Swift Trigger 575905: a possible GRB
  31. IPN triangulation of GRB 131011B (Swift Trigger 574266)
  32. IPN Triangulation of GRB 131014A
  33. GRB 131014A: RATIR Optical and NIR Observations
  34. GRB 131014A: NOT afterglow candidate
  35. GRB 131014A: Nanshan optical observations
  36. GRB 131014A: Swift detection of a possible X-ray afterglow
  37. Fermi403206457: continued P60 observations and fading behavior
  38. Fermi403206457: iPTF detection of a possible optical afterglow
  39. GRB 130925A: Possible signatures of binary nature in the afterglow - Request for observations
  40. GRB131004A: TNG Redshift confirmation
  41. GRB131004A: Magellan Redshift
  42. GRB 131004A: TNG optical afterglow confirmation
  43. GRB 130925A: continuing Swift/XRT monitoring
  44. Konus-Wind observation of GRB 130925A
  45. Observation of possible GRB/TDE 130925A by INTEGRAL/SPI-ACS: three activity episodes
  46. Fermi GBM detection of GRB 130925A and a possible precursor
  47. GRB 130925A: Swift-XRT refined Analysis
  48. GRB 130831A: Maidanak optical observations, possible emerging Supernova
  49. GRB 130913A detected in ground analysis of Swift-BAT data
  50. GRB 130912A: REM optical/NIR upper limits
  51. GRB 130907A: Early Tautenburg detections, red afterglow
  52. GRB 130907A: Skynet DSO-14/Yerkes-41 detections of a possible afterglow
  53. Swift follow-up results of the possible weak INTEGRAL GRB
  54. Swift follow-up of an INTEGRAL possible weak GRB
  55. Swift Trigger 569022: a possible GRB
  56. IPN triangulation of GRB 130828A
  57. IPN triangulation of GRB130821A
  58. GRB 130821A: Swift-XRT observation
  59. Refined IPN Triangulation of GRB 130812B
  60. GRB 130806A: Swift detection of a burst
  61. GRB130803A: GROND detection of possible host
  62. GRB 130722A: Swift/UVOT Detection
  63. GRB 130626A: Retraction of possible X-ray afterglow
  64. GMRT radio detection of GRB 130702A
  65. GRB 130702A: Maidanak optical observations
  66. GRB 130702A (= Fermi 394416326): correction of the GCN #14988 title
  67. GRB 130702A: NOT spectroscopy and redshift of the nearby bright galaxy
  68. Fermi GRB 130702A: Swift XRT and UVOT observations
  69. GRB 130702A / Fermi394416326 : Fermi-LAT detection of a burst
  70. Fermi394416326: FTN detection
  71. Fermi394416326: iPTF detection of a possible optical afterglow
  72. GRB 130627B: Possible Swift-XRT afterglow detection
  73. GRB 130626A: Swift-XRT possible detection and UVOT upper limits
  74. GRB 130603B: Analogy with GRB 090510A and possible connection with a supernova
  75. GRB 130603B: Detection of possible afterglow/kilonova in HST observations
  76. GMRT radio observation of GRB 130603B
  77. GRB 130606A: Errata Ks magnutide in GCN 14792
  78. Swift/UVOT observations of GRB130603A
  79. Swift Trigger 556533 is probably not an astrophysical event
  80. GRB 130518A: Swift XRT and UVOT possible afterglow
  81. GRB 130427A: Continued RATIR Optical and NIR Observations - Photometric Evidence for a New Component
  82. GRB 130427A: Skynet detections of a possible supernova
  83. GRB 130514B Swift-BAT observations
  84. GRB 130515A: GROND Observations
  85. GRB 130427A: Tautenburg 2nd epoch: No break, no clear SN
  86. GRB 130427A: host galaxy observations
  87. GRB 130505B: Swift Candidate Afterglow
  88. Refined IPN Triangulation of GRB 130502B
  89. Konus-Wind observation of GRB 130504C
  90. GRB 130504C: Swift-XRT observations
  91. GRB 130502B: possible TNG counterpart
  92. Trigger 555096: Swift detection of a possible burst
  93. GRB 130427A: Pan-STARRS 1 optical observations
  94. GRB 130427A: Predictions about the occurrence of a supernova
  95. GRB 130427A: GMRT radio detection
  96. GRB 130427A: photo-z of possible SDSS host galaxy
  97. GRB 130427A: high energy gamma-ray detection by AGILE
  98. GRB 130427A: Nishi-Harima NIR Observations
  99. GRB 130427A: P60 early nondetection
  100. Trigger 554491: Swift detection of a spike possibly from Sgr A*

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