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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"

16109 results found.

  1. EP250226a/GRB 250226A: 1.6m Mephisto observations
  2. EP250226a/GRB 250226A: Kinder optical follow-up observations
  3. GRB 250225B: REM NIR upper limits
  4. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  5. EP250223a: CrAO ZTSH optical observation
  6. GRB 250225B: VLT optical and near-infrared candidate counterpart
  7. GRB 250225B: VLT/FORS2 candidate optical afterglow
  8. GRB 250225B: SVOM/GRM observation of a long burst
  9. GRB 250221A: EP-FXT detection of the X-ray afterglow
  10. EP250226a/GRB 250226A: GSP detects optical counterpart
  11. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  12. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  13. EP250226a / GRB 250226A: TRT optical counterpart observation
  14. EP250225a: GSP optical upper limit
  15. EP250223a: GMG Optical Observation
  16. EP250223a: GROWTH-India Telescope optical observations
  17. EP250215A: J band upper limit by SYSU 80cm telescope
  18. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  19. EP250223a: Kinder optical follow-up observations
  20. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  21. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  22. GRB 250219A: EP-FXT afterglow detection
  23. EP250223a: GOTO optical afterglow detections
  24. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  25. EP250223a: REM NIR upper limit
  26. EP250223a: TRT optical afterglow observation
  27. EP250223a: refined analysis of the EP-WXT and FXT observations
  28. EP250223a: 1.6m Mephisto and 50cm array observations
  29. GRB 250221A: TNOT detection of the optical counterpart
  30. EP250223a: SVOM/VT optical observation
  31. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  32. EP250223a: OASDG optical observations
  33. EP250223a: LCO detection of the afterglow
  34. EP250223a: early optical detection by BOOTES-4
  35. EP250223a: NOT redshift z = 2.756
  36. EP250223a: NOT optical afterglow candidate
  37. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  38. GRB 250221A: continued Mondy optical observations, brightening afterglow
  39. GRB 250221A: Optical counterpart detection by LCO.
  40. GRB 250221A: Mondy optical observations
  41. GRB 250221A: Assy optical observations
  42. EP250220a: FTW optical and NIR observations and upper limits
  43. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  44. GRB 250221A: VLT/X-shooter redshift z = 0.768
  45. GRB 250221A: GRANDMA/TAROT Detection
  46. GRB 250221A: NOT optical observations
  47. GRB 250221A: 1.6m Mephisto optical detection
  48. GRB 250221A: AKO Optical Upper Limit
  49. GRB 250221A: Swift/UVOT Detection
  50. EP250220a: Liverpool Telescope upper limits
  51. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  52. GRB 250221A: REM optical/NIR afterglow detection
  53. EP250220a: 1.6m Mephisto observations
  54. EP250220a: Liverpool Telescope optical upper limits
  55. EP250220a: Optical upper limit with Kinder observations
  56. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  57. GRB 250221A: Swift detection of a burst with an optical counterpart
  58. Swift GRB250221.15: Global MASTER-Net OT detection
  59. EP250220a: Xinglong optical upper limit
  60. GRB 250219A: OHP/T193 optical upper limit
  61. GRB 250219A: NOT optical observations
  62. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  63. GRB 250219A: 1.6m Mephisto optical upper limits
  64. GRB 250219A: SVOM/VT optical counterpart
  65. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  66. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  67. GRB 250217C: SVOM/GRM observation
  68. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  69. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  70. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  71. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  72. GRB 250215A / EP250215a: LCO detection of the afterglow
  73. EP250212a: FTW optical and NIR upper limits
  74. GRB 250215A: Swift/UVOT Upper Limits
  75. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  76. EP250215a / GRB 250215A : GTC redshift z = 4.61
  77. GRB 250215A: Fermi GBM Observation
  78. EP250215a / GRB 250215A : NOT optical observations
  79. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  80. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  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. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  85. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  86. GRB 250213A：SVOM/VT optical candidate
  87. EP250207b: Xinglong optical upper limit
  88. EP250212a: Xinglong optical upper limit
  89. GRB 250205A: VIRT Optical Upper Limit
  90. GRB 250205A: Leavitt Observatory optical upper limit
  91. EP250207B: Chandra localization of the X-ray counterpart
  92. EP250212a: Liverpool Telescope optical upper limits
  93. GRB250101A: Radio upper limits from GMRT observations
  94. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  95. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  96. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  97. EP250207b: NOT optical counterpart candidate
  98. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  99. GRB 250205A / EP250205A: radio detection with the VLA
  100. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo

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