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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"

28239 results found.

  1. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  2. EP250226a / GRB 250226A: TRT optical counterpart observation
  3. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  4. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  5. EP250225a: GSP optical upper limit
  6. EP250223a: GMG Optical Observation
  7. EP250225a: Einstein Probe detected of a fast X-ray transient
  8. GRB 250225B: Swift detection of a burst
  9. EP250223a: GROWTH-India Telescope optical observations
  10. GRB 250221A: Swift-BAT refined analysis
  11. EP250215A: J band upper limit by SYSU 80cm telescope
  12. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  13. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  14. EP250223a: Kinder optical follow-up observations
  15. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  16. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  17. GRB 250119B: VZLUSAT-2 detection
  18. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  19. GRB 250202B: VZLUSAT-2 detection
  20. GRB 250222A: SVOM/GRM observation of a burst
  21. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  22. GRB 250206A: VZLUSAT-2 detection
  23. EP250223a: REM NIR upper limit
  24. EP250223a: TRT optical afterglow observation
  25. EP250223a: refined analysis of the EP-WXT and FXT observations
  26. EP250223a: 1.6m Mephisto and 50cm array observations
  27. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  28. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  29. EP250223a: OASDG optical observations
  30. EP250223a: LCO detection of the afterglow
  31. EP250223a: Swift/XRT localization
  32. EP250223a: NOT optical afterglow candidate
  33. EP250223a: Einstein Probe detection of an X-ray transient
  34. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  35. GRB 250221A: Optical counterpart detection by LCO.
  36. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  37. GRB 250221A: GRANDMA/TAROT Detection
  38. GRB 250221A: Swift-XRT refined Analysis
  39. GRB 250221A: NOT optical observations
  40. GRB 250221A: 1.6m Mephisto optical detection
  41. GRB 250221A: AKO Optical Upper Limit
  42. GRB 250221A: Swift/UVOT Detection
  43. EP250220a: Liverpool Telescope upper limits
  44. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  45. GRB 250221A: REM optical/NIR afterglow detection
  46. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  47. GRB 250221A: Enhanced Swift-XRT position
  48. EP250220a: 1.6m Mephisto observations
  49. EP250220a: Liverpool Telescope optical upper limits
  50. EP250220a: Optical upper limit with Kinder observations
  51. SVOM trigger sb25022102 is not an astrophysical event
  52. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  53. GRB 250221A: Swift detection of a burst with an optical counterpart
  54. Swift GRB250221.15: Global MASTER-Net OT detection
  55. EP250220a: Xinglong optical upper limit
  56. GRB 250219A: Swift/UVOT Upper Limits
  57. GRB 250219A: OHP/T193 optical upper limit
  58. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  59. GRB 250219A: 1.6m Mephisto optical upper limits
  60. GRB 250219A: Swift-XRT observations
  61. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  62. Konus-Wind detection of GRB 250215A / EP250215a
  63. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  64. GRB 250217C: Swift-XRT observations
  65. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  66. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  67. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  68. GRB 250217C: SVOM/GRM observation
  69. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  70. SVOM/sb25021804: SVOM detection of a long X-ray transient
  71. GRB 250213A: Swift-XRT observations
  72. GRB 250216A: AstroSat CZTI detection
  73. GRB 250217C: AstroSat CZTI detection of a short burst
  74. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  75. GRANDMA/OPD observations of GRB250215A
  76. GRB 250215A / EP250215a: LCO detection of the afterglow
  77. GRB 250215A: Swift/UVOT Upper Limits
  78. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  79. GRB 250215A: Fermi GBM Observation
  80. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  81. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  82. GRB 250215A: Swift-XRT refined Analysis
  83. GRB 250215A: SVOM/GRM observation
  84. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  85. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  86. EP250207b: Xinglong optical upper limit
  87. EP250212a: Xinglong optical upper limit
  88. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  89. EP250212a: Global MASTER-Net observations report
  90. GRB 250205A: VIRT Optical Upper Limit
  91. GRB 250205A: Leavitt Observatory optical upper limit
  92. EP250207B: Chandra localization of the X-ray counterpart
  93. EP250212a: Liverpool Telescope optical upper limits
  94. GRB250101A: Radio upper limits from GMRT observations
  95. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  96. EP250207B: GTC z-band Observations
  97. Fermi GRB 250212A: Global MASTER-Net observations report
  98. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  99. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  100. Fermi trigger No 760945500: Global MASTER-Net observations report

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