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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').
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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"

20546 results found.

  1. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  2. GRB 250330A: VLT/FORS2 Optical Observations
  3. GRB 250330A: Prompt Swift-XRT position
  4. GRB 250329B: Swift-XRT afterglow detection
  5. GRB 250330A: Swift detection of a burst
  6. GRB 250329B: SVOM/C-GFT optical upper limit
  7. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  8. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  9. GRB250329A: REM optical afterglow detection
  10. GRB 250329B: GWAC-F50A optical upper limit
  11. GRB 250329A: Swift-XRT afterglow detection
  12. GRB 250328A: SVOM/VT optical observation
  13. GRB 250329A: Fading optical counterpart detection by LCO.
  14. GRB 250328A: SVOM/C-GFT optical upper limit
  15. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  16. GRB 250329A: VLT/X-shooter redshift z = 2.921
  17. GRB 250329A: SVOM/VT optical counterpart confirmation
  18. GRB 250329A: SVOM detection of a burst
  19. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  20. GRB 250327B: J-band observations with WINTER
  21. GRB 250327B: LCO optical counterpart detection
  22. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  23. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  24. GRB 250327B: CrAO and SAO RAS Optical Observations
  25. EP250315a: Pan-STARRS r and i-band imaging and photometry
  26. GRB 250327b: Liverpool Telescope optical observations
  27. GRB 250322A: GRANDMA/TNOT optical upper limits
  28. GRB 250327A: SVOM/VT upper limits on the XRT position
  29. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  30. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  31. GRB 250327B: Las Cumbres optical counterpart detection
  32. GRB 250327B: 1.6m Mephisto optical observations
  33. GRB 250327B: NOT spectroscopic redshift z = 3.035
  34. GRB 250327B: SVOM/VT optically bright counterpart
  35. GRB 250327B: SAO RAS optical candidate
  36. GRB 250327B: SVOM detection of a burst
  37. GRB 250327A: J-band observations with WINTER
  38. GRB 250327A: SVOM/VT optical candidate
  39. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  40. GRB 250327A: DDOTI Optical Observations
  41. GRB 250327A: COLIBRÍ optical upper limit
  42. IPN triangulation of GRB 250322B
  43. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  44. EP250321a: Mondy AZT-33IK Continued Optical Observations
  45. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  46. GRB 250322A: third epoch of NOT optical observations
  47. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  48. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  49. GRB 250322A: further NOT optical observations
  50. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  51. GRB 250322A: Swift/UVOT Upper Limits
  52. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  53. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  54. GRB 250321B: Swift-XRT observations
  55. EP250321a: TNOT Observation of Optical Counterpart
  56. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  57. GRB 250322A: VLT optical observations
  58. GRB 250322A: VLT near-infrared observations
  59. FRB 250316A: DDOTI Continued Optical Observations
  60. GRB 250322A: NOT optical upper limits
  61. GRB 250322A: Enhanced Swift-XRT position
  62. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  63. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  64. EP250321a: Liverpool Telescope optical follow-up
  65. EP250321a: Mondy AZT-33IK Optical Observations
  66. GRB 250322A: Swift detection of a short burst
  67. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  68. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  69. EP250321a: KAIT optical observations
  70. EP250321A: COLIBRÍ Continuing Optical Observations
  71. EP250321a: WFST optical observations
  72. EP250321a: Xinglong 216 decaying optical observations
  73. GRB 250321A: Swift-XRT refined Analysis
  74. EP 250321A: Optical counterpart detection by LCO.
  75. EP250321a: Kinder optical follow-up observations
  76. GRB 250321A: Swift/UVOT Upper Limits
  77. GRB 250320B: SVOM/GRM observation of a long burst
  78. EP250321a: LCO optical counterpart detection
  79. EP250321A: COLIBRÍ Optical Observations
  80. GRB 250320B: AstroSat CZTI detection
  81. EP250321a: REM optical/NIR afterglow detection
  82. EP250321a: TRT optical counterpart detection
  83. EP250321a: Einstein Probe detection of an X-ray transient
  84. GRB 250321A: GOTO optical upper limits
  85. GRB 250314A: Keck/NIRC2 J-band upper limit
  86. EP250226a/GRB 250226A: KAIT optical observations
  87. GRB 250321A: Swift detection of a burst
  88. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  89. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  90. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  91. EP250302a: VLA observations
  92. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
  93. GRB 250317C: SVOM/GRM observation of a long burst
  94. GRB 250317B: Leavitt Observatory optical upper limit
  95. GRB 250317B: Mondy AZT-33IK Optical Observations
  96. GRB 250317B: NOT optical observations suggest an optical plateau phase
  97. GRB 250317B: OHP/T193 optical observations
  98. GRB250312A: Swift/UVOT Upper Limits
  99. GRB 250317B: REM optical/NIR observations
  100. GRB 250316A: Swift/UVOT Upper Limits

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