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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"

20554 results found.

  1. EP250302a: Montarrenti Observatory optical detection
  2. EP250302a: Nanshan/HMT optical counterpart detection
  3. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  4. GRB 250225B: VLT near-infrared afterglow confirmation
  5. EP250228a: Optical observations with Kinder and Swift/UVOT
  6. GRB 250226A: KAO Optical Upper Limit
  7. GRB 250226A: AbAO AS-32 Optical Upper Limit
  8. EP250227a: TRT optical upper limit
  9. GRB 250225B: VLT/HAWKI near-infrared observations
  10. EP250227a: Optical upper limits with Kinder observations
  11. EP250227a: NOT optical observations
  12. EP250227a: Einstein Probe detected of a fast X-ray transient
  13. EP250228a: updates on the EP observations
  14. EP250223a: J band upper limit by SYSU 80cm telescope
  15. EP250228a: Einstein Probe detection of an X-ray transient
  16. GRB 250225B: VLT/Xshooter imaging
  17. GRB 250205A / EP250205A: further radio observations with the VLA
  18. EP250225a: NOT optical candidate counterpart
  19. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  20. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  21. EP250225a: TRT optical upper limits
  22. EP250226a/GRB 250226A: 1.6m Mephisto observations
  23. EP250226a/GRB 250226A: Kinder optical follow-up observations
  24. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  25. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  27. GRB 250221A: ATCA Detections and Upper Limits
  28. GRB 250225B: REM NIR upper limits
  29. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  30. EP250223a: CrAO ZTSH optical observation
  31. GRB 250225B: VLT optical and near-infrared candidate counterpart
  32. GRB 250225B: SVOM/GRM observation of a long burst
  33. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  34. EP250226a / GRB 250226A: TRT optical counterpart observation
  35. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  36. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  37. EP250223a: GMG Optical Observation
  38. EP250225a: Einstein Probe detected of a fast X-ray transient
  39. EP250223a: GROWTH-India Telescope optical observations
  40. EP250215A: J band upper limit by SYSU 80cm telescope
  41. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  42. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  43. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  44. EP250223a: Kinder optical follow-up observations
  45. GRB 250222A: SVOM/GRM observation of a burst
  46. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  47. EP250223a: REM NIR upper limit
  48. EP250223a: TRT optical afterglow observation
  49. EP250223a: refined analysis of the EP-WXT and FXT observations
  50. EP250223a: 1.6m Mephisto and 50cm array observations
  51. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  52. 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
  53. EP250223a: OASDG optical observations
  54. EP250223a: early optical detection by BOOTES-4
  55. EP250223a: NOT redshift z = 2.756
  56. EP250223a: NOT optical afterglow candidate
  57. GRB 250221A: VLA radio detection
  58. EP250223a: Einstein Probe detection of an X-ray transient
  59. GRB 250221A: Optical counterpart detection by LCO.
  60. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  61. GRB 250221A: GRANDMA/TAROT Detection
  62. GRB 250221A: 1.6m Mephisto optical detection
  63. GRB 250221A: AKO Optical Upper Limit
  64. GRB 250221A: Swift/UVOT Detection
  65. EP250220a: Liverpool Telescope upper limits
  66. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  67. GRB 250221A: REM optical/NIR afterglow detection
  68. GRB 250221A: Enhanced Swift-XRT position
  69. EP250220a: 1.6m Mephisto observations
  70. EP250220a: Liverpool Telescope optical upper limits
  71. EP250220a: Optical upper limit with Kinder observations
  72. SVOM trigger sb25022102 is not an astrophysical event
  73. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  74. GRB 250221A: Swift detection of a burst with an optical counterpart
  75. EP250220a: Xinglong optical upper limit
  76. EP250220a: EP-WXT detection of a fast X-ray transient
  77. Konus-Wind detection of GRB 250217C (short)
  78. GRB 250219A: Swift/UVOT Upper Limits
  79. GRB 250219A: OHP/T193 optical upper limit
  80. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  81. GRB 250219A: 1.6m Mephisto optical upper limits
  82. Konus-Wind detection of GRB 250215A / EP250215a
  83. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  84. GRB 250217C: Swift-XRT observations
  85. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  86. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  87. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  88. GRB 250217C: SVOM/GRM observation
  89. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  90. SVOM/sb25021804: SVOM detection of a long X-ray transient
  91. GRB 250213A: Swift-XRT observations
  92. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  93. GRANDMA/OPD observations of GRB250215A
  94. GRB 250215A / EP250215a: LCO detection of the afterglow
  95. GRB 250215A: Swift/UVOT Upper Limits
  96. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  97. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  98. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  99. GRB 250215A: SVOM/GRM observation
  100. EP250215a / GRB 250215A: AstroSat CZTI detection

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