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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

20554 results found.

  1. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  2. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  3. GRB 250331C: Swift detection of a burst
  4. GRB 250331B: Swift detection of a burst
  5. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  6. GRB 250330A: Swift/UVOT Upper Limits
  7. GRB 250330A: Swift-XRT afterglow detection
  8. GRB 250328A: 1.6m Mephisto optical observations
  9. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  10. GRB 250330A: VLT/FORS2 Optical Observations
  11. GRB 250330A: Prompt Swift-XRT position
  12. GRB 250329B: Swift-XRT afterglow detection
  13. GRB 250330A: Swift detection of a burst
  14. GRB 250329B: SVOM/C-GFT optical upper limit
  15. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  16. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  17. GRB250329A: REM optical afterglow detection
  18. GRB 250329B: GWAC-F50A optical upper limit
  19. GRB 250329A: Swift-XRT afterglow detection
  20. GRB 250328A: SVOM/VT optical observation
  21. GRB 250329A: Fading optical counterpart detection by LCO.
  22. GRB 250328A: SVOM/C-GFT optical upper limit
  23. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  24. GRB 250329A: VLT/X-shooter redshift z = 2.921
  25. GRB 250329A: SVOM/VT optical counterpart confirmation
  26. GRB 250329A: SVOM detection of a burst
  27. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  28. GRB 250327B: J-band observations with WINTER
  29. GRB 250327B: LCO optical counterpart detection
  30. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  31. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  32. GRB 250327B: CrAO and SAO RAS Optical Observations
  33. EP250315a: Pan-STARRS r and i-band imaging and photometry
  34. GRB 250327b: Liverpool Telescope optical observations
  35. GRB 250322A: GRANDMA/TNOT optical upper limits
  36. GRB 250327A: SVOM/VT upper limits on the XRT position
  37. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  38. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  39. GRB 250327B: Las Cumbres optical counterpart detection
  40. GRB 250327B: 1.6m Mephisto optical observations
  41. GRB 250327B: NOT spectroscopic redshift z = 3.035
  42. GRB 250327B: SVOM/VT optically bright counterpart
  43. GRB 250327B: SAO RAS optical candidate
  44. GRB 250327B: SVOM detection of a burst
  45. GRB 250327A: J-band observations with WINTER
  46. GRB 250327A: SVOM/VT optical candidate
  47. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  48. GRB 250327A: DDOTI Optical Observations
  49. GRB 250327A: COLIBRÍ optical upper limit
  50. IPN triangulation of GRB 250322B
  51. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  52. EP250321a: Mondy AZT-33IK Continued Optical Observations
  53. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  54. GRB 250322A: third epoch of NOT optical observations
  55. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  56. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  57. GRB 250322A: further NOT optical observations
  58. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  59. GRB 250322A: Swift/UVOT Upper Limits
  60. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  61. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  62. GRB 250321B: Swift-XRT observations
  63. EP250321a: TNOT Observation of Optical Counterpart
  64. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  65. GRB 250322A: VLT optical observations
  66. GRB 250322A: VLT near-infrared observations
  67. FRB 250316A: DDOTI Continued Optical Observations
  68. GRB 250322A: NOT optical upper limits
  69. GRB 250322A: Enhanced Swift-XRT position
  70. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  71. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  72. EP250321a: Liverpool Telescope optical follow-up
  73. EP250321a: Mondy AZT-33IK Optical Observations
  74. GRB 250322A: Swift detection of a short burst
  75. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  76. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  77. EP250321a: KAIT optical observations
  78. EP250321A: COLIBRÍ Continuing Optical Observations
  79. EP250321a: WFST optical observations
  80. EP250321a: Xinglong 216 decaying optical observations
  81. GRB 250321A: Swift-XRT refined Analysis
  82. EP 250321A: Optical counterpart detection by LCO.
  83. EP250321a: Kinder optical follow-up observations
  84. GRB 250321A: Swift/UVOT Upper Limits
  85. GRB 250320B: SVOM/GRM observation of a long burst
  86. EP250321a: LCO optical counterpart detection
  87. EP250321A: COLIBRÍ Optical Observations
  88. GRB 250320B: AstroSat CZTI detection
  89. EP250321a: REM optical/NIR afterglow detection
  90. EP250321a: TRT optical counterpart detection
  91. EP250321a: Einstein Probe detection of an X-ray transient
  92. GRB 250321A: GOTO optical upper limits
  93. GRB 250314A: Keck/NIRC2 J-band upper limit
  94. EP250226a/GRB 250226A: KAIT optical observations
  95. GRB 250321A: Swift detection of a burst
  96. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  97. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  98. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  99. EP250302a: VLA observations
  100. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate

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