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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"

16112 results found.

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

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